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The hospital system is one of the most critical systems in the city and plays an irreplaceable role in the whole process of earthquake disasters. This paper presents a method that considers the medical supply–demand relationship to quantify the functionality and functional loss of a hospital system under earthquake conditions, which is different from the current quantitative method that only considers internal factors of the hospital system. This method provides a "finest granularity" method for the division of quantitative evaluation units of hospital system functionality based on GIS overlay. Secondly, the functionality of the hospital system considering the medical supply–demand relationship and the quantitative metric, substitution capacity of medical resources (SCMR), is constructed. Then, we propose a quantification method of SCMR by combining the spatial and network analysis methods. Finally, a hospital system in eastern China is considered as an illustrative example. The impact of changes in the medical supply and demand at different times of the day on the hospital system functionality is analyzed. The results show that the medical supply and demand can impact hospital system functionality. The loss of medical supply causes a decline of hospital system functionality, while changes in the spatial aggregation of medical demand positively affect the loss of hospital system functionality. This paper can use the proposed method to quantify the hospital system functionality and reflect the balance of the medical supply–demand relationship before and after the earthquake. It can help decision-maker develop scientific post-earthquake emergency plans and enhance hospital system resilience. [ABSTRACT FROM AUTHOR]

A Mw 6.6 earthquake struck Luding county, in Sichuan province of China on September 5, 2022, causing severe damage of nearby infrastructures. The earthquake indicates an awakening of southeast branch of Xianshuihe fault since the last 1973 Mw 7.6 Luhuo earthquake in Sichuan, thus attracting attention from the public. A physics-based method, combining spectral element method (SEM) and finite element method (FEM), was presented in this paper to investigate the correlation between near-fault motions and response of a road tunnel, which has a closest distance of about 6.0 km to the fault. This method allows to incorporate the rupture details, geological irregularity, 3D velocity structure, as well as the underground tunnel. The ground motions simulated by SEM were validated by comparison to specific station records and empirical ground motion model (GMM), which were subsequently input into the tunnel to obtain its axial deformation and sectional inner forces. Parametric study on tunnel alignment was conducted, and wavelet transformation was used to extract dynamic pulses from the ground motions. The results show that the tunnel response is remarkably affected by dynamic pulse directivity, and the axial forces could be dominated by permanent fault displacement for tunnel of the strike-normal alignment. [ABSTRACT FROM AUTHOR]

This paper presents the emergency response to the barrier lake created by the Mw 6.5 earthquake on August 3, 2014, in Niulan River which is situated in Yunnan Province, southwest China. The lake, behind 83- to 103-m-high landslide dam, has a storage capacity of 260 million m. The Hongshiyan hydropower station, situated just upstream of the landslide dam, was submerged by the lake water. The rescue actions include building an 8-m-deep drainage channel in the flood season, draining the lake water via a water release tunnel and rebuilding the landslide dam as a permanent structure. This paper presents the considerations and processes in deciding on the emergency actions. One major consideration is to minimize the hazards caused by a possible dam break flood induced by Hongshiyan barrier lake in the flood season. It was found that the barrier lake is classified as 'grade I: extremely high risk' in which the 5- and 20-year floods should be used for design and check purposes of emergency works, respectively. The dam break flood evaluations indicated that an 8-m-deep diversion channel should be constructed in order to reduce the total amount of the released reservoir storage and to prevent possible overtopping of the downstream Huangjiaoshu rockfill dam. This study was based on an improved analytical approach to dam break flood modeling and a handy spread sheet developed by the authors. The considerations on various risks and the key analytical technology for dam break flood predictions described in this paper may be useful for other similar cases. [ABSTRACT FROM AUTHOR]

Due to China's exposure and susceptibility to natural hazards, it is important for governments and aid agencies to have tools that enable effective post-disaster livelihood recovery in creating self-sufficiency for the affected population. This paper introduces a framework of critical components that constitute a successful livelihood recovery by studying the perceptions and perspectives of those affected by the 2013 Lushan earthquake in Sichuan Province. A mixed method, namely a pilot study, questionnaire survey and interviews, was used. While the populations surveyed valued the employment benefits of creating new market and economic sectors in areas where rural farming was predominant prior to the earthquake, they considered that recovery of their housing was most essential for livelihood diversification. External assistance was also regarded highly in assisting with livelihood recovery, in which family ties and social connections seemed to have played a larger role than that of government agencies and NGOs. Lastly, the results highlighted that a goal of livelihood recovery cannot be achieved without individual well-being being considered, in relation to people's perceptions about quality of life and their physical and mental health. This paper aims to assist the Chinese policy makers and practitioners in disaster recovery in setting an agenda of preparing for livelihood recovery in peace times, or of post-disaster recovery planning should a disaster event occurs so that the economic impact and livelihood burdens of those affected can be effectively mitigated. [ABSTRACT FROM AUTHOR]

Natural disaster risk assessment is of great significance to increasingly severe disaster prevention and mitigation work. However, the method of risk assessment for multi-disaster is still a difficult problem. In this paper, a novel multi-disaster risk assessment framework based on multi-dimensional correlation analysis is proposed, which combines numerical correlation, geographic correlation and multi-disaster correlation, from a more comprehensive point of view to give a reasonable multi-disaster risk assessment. Firstly, in the perspective of numerical correlation, gray correlation method is used to quantify and rank impact factors system data of natural disasters. Then, the factor detection module of geographic detector is used to detect the driving force of factors, which distributes the weights, based on the geographic correlation view. Finally, combining with above results, a multi-disaster coupling risk assessment model (MRAM) is established, which focus on multi-disaster correlation, to assess the integrated multi-disaster risk. The multi-disaster risk assessment framework is applied to evaluate the integrated risk of multiple natural disasters like flood, earthquake and storm surge in Tianjin City, China. The integrated risk is compared with the history natural disasters intensity and the risk results obtained by TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution), which shows that the MRAM proposed is more reasonable to reflect the risk distribution. Furthermore, the framework is expected to be extended to multi-disaster risk assessment in other areas and contribute to building good disaster prevention and mitigation system. [ABSTRACT FROM AUTHOR]

The temporal distribution of earthquakes provides important basis for earthquake prediction and seismic hazard analysis. The relatively limited records of strong earthquakes have often made it difficult to study the temporal distribution models of regional strong earthquakes. However, there are hundreds of years of complete strong earthquake records in the North China Seismic Zone, providing abundant basic data for studying temporal distribution models. Using the data of M ≥ 6.5 earthquakes in North China as inputs, this paper estimates the model parameters using the maximum likelihood method with Poisson, Gamma, Weibull, Lognormal and Brownian passage time (BPT) distributions as target models. The optimal model for describing the temporal distribution of earthquakes is determined according to Akaike information criterion (AIC),and Kolmogorov–Smirnov test (K–S test). The results show that Lognormal and BPT models perform better in describing the temporal distribution of strong earthquakes in North China. The mean recurrence periods of strong earthquakes (M ≥ 6.5) calculated based on these two models are 8.1 years and 13.2 years, respectively. In addition, we used the likelihood profile method to estimate the uncertainty of model parameters. For the BPT model, the mean and 95% confidence interval of recurrence interval μ is 13.2 (8.9–19.1) years, and the mean and 95% confidence interval of α is 1.29 (1.0–1.78). For the Lognormal model, the mean value and 95% confidence interval of v is 2.09 (1.68–2.49), the mean value exp (v) corresponding to earthquake recurrence interval is 8.1 (5.4–12.1) years. In this study, we also calculated the occurrence probability of M ≥ 6.5 earthquakes in the North China Seismic Zone in the future, and found that the probability and 95% confidence interval in the next 10 years based on the BPT model is 35.3% (26.8%-44.9%); the mean value and 95% confidence interval of earthquake occurrence probability based on the Lognormal distribution is 35.4% (22.9%-49.7%); the mean probability and 95% confidence interval based on the Poisson model is 53.1% (41.1%-64%). The results of this study may provide important reference for temporal distribution model selection and earthquake recurrence period calculation in future seismic hazard analysis in North China. [ABSTRACT FROM AUTHOR]

The earthquake outbreak on 12 May 2008, in Wenchuan County caused long-term instability and frequent geological hazards on the mountain slopes in the earthquake area. Considering Miansi town in the strong earthquake area as an example, this paper analyses the development and characteristics of landslides in the 10 years after the earthquake. We collected five periods of remote sensing images in the 10 years after the earthquake, obtained the corresponding landslide distribution and activity characteristics, and then analysed the development of landslide activity over the 10 years. The total area of the landslides grew intensively from 2008 to 2014, and then the growth rate slowed down significantly after the heavy rainfall event on 10 July 2013. At the same time, the influence of slope, slope aspect, distance to a river channel, elevation, and other factors on the probability of landslides is analysed by using the distribution of the landslides. The areas that are prone to landslides, which mainly include the areas with elevations of 1700–3200 m, the areas with slopes of 30–60°, the areas with aspects of 90°–225° (with north having an aspect of 0°), and the area that are less than 200 m from a river channel, are divided according to the distribution density. [ABSTRACT FROM AUTHOR]

On the basis of data obtained from China Earthquake Administration and China National Statistics Bureau, this paper focuses on the earthquake disaster loss characteristics in 31 provinces or municipalities of China from 1993 to 2016. The trends of direct economic losses, casualties and affected population are also analyzed by constructing two relative earthquake loss indexes (losses/GDP and losses/E) and employing gray correlation theory. Results show that during the 24 years, without taking Wenchuan Ms8.0 earthquake into account, the direct economic losses exhibit a significant increasing trend while losses/GDP also increases but is not significant. Meanwhile, the injuries and affected population both witness a decline trend but the fatalities show the opposite. According to the correlational degree of each year, 8 years (1995, 1996, 1998, 2003, 2008, 2010, 2013 and 2014) suffered losses of equal or above moderate grade. Regionally, the western China suffered the most accumulative direct economic losses and losses/GDP. However, the ranking results of losses/E demonstrate that the central China is the most vulnerable when confronting with the same earthquake. Specifically, Sichuan and Yunnan suffered losses of extra-large grade, Qinghai of large grade and Tibet, Xinjiang and Guangdong of moderate grade. These discoveries are helpful for earthquake mitigation and preparedness as well as earthquake loss evaluation in China. [ABSTRACT FROM AUTHOR]

The South China Sea Tsunami Advisory Center (SCSTAC) established by China, under the aegis of UNESCO's Intergovernmental Oceanographic Commission (UNESCO/IOC), had inaugurated commencing its full operation on November 5, 2019. This center is operating 24 × 7 h and round-the-clock shift to monitor tsunami hazard that pose a serious threat to countries which bordering the South China Sea (SCS) region. Prior to the official operation, SCSTAC had taken action for the last 10 years in upgrading their technology capability which are real-time earthquake monitoring and the processing system that is crucial to be able providing the international standard of tsunami warning services in the SCS and its adjacent areas. This paper briefly reviewed on the initiation steps and its developments of the South China Sea region Tsunami Warning and Mitigation Systems, tectonic setting as well as the characteristics of historical earthquakes and tsunamis in the region. In addition, we highlighted the structure and basic functions of the earthquake monitoring and processing system, earthquake location, source mechanism solution and finite fault model inversion using the real-time seismic waveform data from regional and global seismographic networks that will result in the rapid source parameters estimation for a larger earthquake in tsunami warning. Numerous simulations and hands-on events have shown that the preliminary earthquake parameters could be determined less than 8 min after earthquake. The W phase method is used and be able to produce rapid and reliable estimation of the moment magnitude and source mechanism for larger events within 10–15 min from earthquake origin time. A finite fault model can be acquired just after the earthquake event via computing teleseismic body-wave inversion program. The earthquake monitoring and processing system provide accurate and reliable information in contributing to tsunami warning services, thus promoting the development of tsunami warning technologies, which enhancing the tsunami warning capability and tsunami emergency responses. These high-end technology can be used in facilitating others such as marine disaster prevention, mitigation and its risk reduction. [ABSTRACT FROM AUTHOR]

China is one of the countries most affected by earthquakes. Improving public cognition and response to earthquake disaster (EDCR) is an effective means to reduce seismic risk and losses. The 2013 Lushan earthquake area was also stricken by the 2008 Wenchuan earthquake. Most of the residents in this area have been affected by both earthquakes, which provides a rare opportunity to gain insight into the interaction between public's EDCR and their earthquake disaster experience. Using a questionnaire survey on over 200 local residents selected by stratified sampling method, this paper investigates the public's cognition and response capability with regard to earthquake disaster in the 2013 Mw6.6 Lushan earthquake area, Sichuan Province, China, with a particular emphasis on exploration on the relationship between people's earthquake disaster experience and their disaster cognition and response behaviors. The results show that the overall EDCR level of local residents is moderate—their average cognition and response score for earthquake disaster is only 0.60. The number of earthquakes experienced, education, and family income level are the three most important factors that significantly impact an individual's overall EDCR capability. Those who have experienced more earthquakes better adapt to the impacts of disaster. Especially, the experience learned from the 2008 Mw7.9 Wenchuan earthquake played a positive role in the cognition and response of the public to the 2013 Lushan earthquake. In addition, people with higher education could master more knowledge of earthquake disaster and better control their emotions. Similarly, respondents with a higher family income had more resources and ways to engage in more reasonable response behaviors to manage disaster effects. Based on these findings, it is suggested that local policy-makers implement targeted earthquake disaster education and knowledge dissemination strategies, especially develop and expand various experiential learning modes (e.g., emergency exercise/drilling, situational learning, virtual reality, scenario approach, safety/disaster experience center, participatory activities) for the local public and beyond to more effectively strengthen their cognition of disaster and response capability. [ABSTRACT FROM AUTHOR]

Long-term outcomes and collaborative governance are particularly worthy of discussion when examining the recovery process from natural disasters. In the long and dynamic processes of recovery, how do the primary participants responsible for recovery adapt and change to meet social and economic objectives? This paper argues that the approach to recovery following the Wenchuan Earthquake in China experienced a transformation from paired assistance under centralized political mobilization to collaborative networks. Based on an in-depth case study of the Shanghai–Dujiangyan Paired Assistance Policy, we find that recovery from the Wenchuan Earthquake can be demarcated and described in terms of three stages involving government-oriented project aid, contract-oriented industrial redevelopment, and network-oriented collaborative governance. Four determinants contributed to these transformation processes: (1) The central government was promoted as the responsible entity for guiding recovery efforts from the catastrophe, and the effective political mobilization under the Paired Assistance Policy (PAP) and interactions between subnational assisting governments ensured the timeliness, diversity, and quality of aid projects; (2) industry recovery policies provided the policy environment for enterprises to participate in industrial recovery, and beneficial reciprocity became the key attraction for outside private enterprises to participate in the industrial recovery of Dujiangyan; (3) the participation of social organizations as emergent organizations in the recovery contributed to the formation of collaborative networks; and (4) the trust, friendship, and mutually beneficial relationships that were developed over the 3-year term of the PAP provided a strong foundation for the formation of collaborative networks, which were essential to facilitating longer term recovery. [ABSTRACT FROM AUTHOR]

Seismically triggered landslides can cause great damage to the road construction in mountainous areas. The permanent displacement analysis based on Newmark sliding-block model can evaluate risk of these landslides from the perspective of deformation damage and overall failure probability of slopes. However, the sliding-block model does not consider the attenuation effect of the shear strength on the sliding surface during earthquake, causing the calculated value of Jibson method to be less than the actual value. Therefore, the Newmark model was modified by adding attenuation coefficients to the effective internal friction angle and the effective cohesion of geologic units. The landslide areal density was proposed for hazard zoning with the Wenchuan earthquake data. The results showed that the predicted values agreed well with the real distribution of the landslides triggered by the Lushan earthquake. The proposed hazard zoning method in this paper can predict the severity of seismic landslides in consideration of the environmental changes in mountainous regions after the earthquake and provide support for the site selection in highly seismic areas. [ABSTRACT FROM AUTHOR]

According to the statistical analysis, a total of 25 M ≥ 8 earthquakes occurred in Mainland China and neighborhood from 1300 to 2015. The seismic activity of M ≥ 8 earthquakes has shown an obvious commensurability and self-organized orderliness. It should be remarked especially that the Nepal great earthquakes have a significant relationship with the M ≥ 8 earthquakes in West China. Within such a short 100 years from 1902 to 2001, three ordered pairs of M ≥ 8 earthquakes took place in West China: 1902-1906, 1927-1931, and 1997-2001, each pair of two earthquakes had a time interval of 4 years, which is a quite unique and rare example in the earthquake history of China and the whole world. Based on the information forecasting theory of Wen-Bo Weng, this paper focuses on the summary of the ordered network structure of M ≥ 8 earthquakes, supplements new information of three M ≥ 8 earthquakes occurred in Nepal: M8 in 1833, M8.1 in 1934, and M8.1 in 2015, hence constructs and further optimizes the 2D- and 3D-ordered network structure of M ≥ 8 earthquakes to make prediction research. The results show that the occurrence of the 2015 Nepal M8.1 earthquake indicates the beginning of another M ≥ 8 earthquake cycle in West China. The great or strong earthquakes will probably happen in the Qinghai-Xizang Plateau area and gradually migrate from the south to the north for decades. A new ordered pair of M ≥ 8 earthquakes will probably occur around 2022 and 2026 in West China, as well as a single event around 2029. [ABSTRACT FROM AUTHOR]

Most seismic casualty estimations are based on the vulnerability of various categories of structure and facilities in the region concerned. These approaches require detailed inventory database of the structures and facilities in the region. In China, however, the data is not always available, especially for some underdeveloped regions. This motivates the development of empirical models that use historical casualty data for earthquakes and provide a country- or region-specific earthquake death rate as a function of ground shake. However, diminishing divergences in fitting method and obtaining higher accuracy are still a great challenge. Building on the findings of previous research, the present paper employs vulnerability curves to express the relation between seismic intensity and mortality. From data of the death rate by intensity, curves are established for the whole of China and western China. Some methodological improvements are also discussed. To validate the curves, data from four recent strong earthquakes occurred in western China are used, and the best curves for estimation are selected and compared with similar models. Results indicate that the established curves for western China give a better estimation for the four earthquakes and the logistic functions show higher accuracy. They can be used to clarify the magnitude of seismic deaths in western China when structure and facility data are unavailable. Uncertainties and the application of the models are also analyzed and discussed in the conclusion. [ABSTRACT FROM AUTHOR]

In April 2013, a 7.0 Mw earthquake struck along the Longmen Shan fault in the city of Ya'an, Sichuan Province, China, causing serious damage. The invaluable contributions of the non-governmental organizations (NGOs) in dealing with this disaster highlighted the significance of government-NGO relationships in post-disaster reconstruction and the effect this has on the efficiency and quality of post-disaster reconstruction. This paper examines government-NGO relationships (GNR) in the post-Lushan earthquake period as a multi-stakeholder collaborative problem based on organizational lifecycle perspectives through the birth, growth, stability, and saturation stages. Two-year field research was conducted in the affected areas which identified the GNR as a bridged government-NGO relationship (BGNR) during the reconstruction period, with the Ya'an service center acting as the bridging organization. The BGNR's experience was compared to the previous Wenchuan earthquake, and the general BGNR post-disaster reconstruction situation is discussed on two dimensions: mutuality and organizational identity. [ABSTRACT FROM AUTHOR]

The aim of this paper is to propose a location model of earthquake emergency service depot on the basis of hybrid multi-attribute decision-making method. The advantage of the proposed method is that practical mixed uncertainty of location decision information is considered, and the corresponding factors that affect the location of transfer stations are contained. To solve the location problem, a hybrid multi-attribute decision procedure without information transformation is developed. Besides, a novel weighting method and aggregation process is given. Finally, a numerical example is provided to show the feasibility and validity of the proposed method. [ABSTRACT FROM AUTHOR]

Historical tsunami records in the South China Sea are collected and analyzed in this paper. There have been about 54 tsunamis in the South China Sea since 1076. The impacts of the transoceanic tsunamis on the southeast coast of China are weak. However, the regional tsunamis in the South China Sea bring varying degrees of influence to the south coast of China, which occurred about 18 times. By the analysis of the potential tsunami sources in the South China Sea, numerical simulations of tsunami induced in the Manila Trench are carried out. It is found that the tsunami wave height is small near Haikou if the general earthquake tsunami occurred. But the tsunami wave height is large when a giant earthquake of M9.3 occurred. If this extreme situation arises, the impacts to the coast of Haikou will be serious. [ABSTRACT FROM AUTHOR]

Households vary in their ability to deal with disasters, and this may lead to different recovery results. Aiming to examine this differentiation, this paper studied the 2009 Yao'an earthquake in China. Surveys of 200 destroyed rural households were conducted in field investigations and follow-ups at 1 month, 1 year, and 1.5 years after the earthquake. The results showed a clear difference in recovery, the households observably being classified into five groups. These are the O group, which has different recovery time and economic cost from the other four; and the special group, comprising E T and E T (vulnerable during recovery); E T (strong during recovery); and E T (neither vulnerable nor strong). Logistic regression analysis revealed that differentiation in recovery patterns arose from the combined effect of demographic factors and external assistance provided to households. Lower income is the root cause of vulnerability in some households during the recovery process. However, other factors cause recovery differences between the two vulnerable groups, causing the economic recovery cost of the E T group to be lower, and the recovery time of the E T group to be longer. There was consensus that external assistance had an impact on all households. The more provided and the earlier it arrived, the lower the cost for recovery and the shorter the recovery time. This study shows that research on group differentiation of recovery is useful in understanding post-earthquake recovery processes and calls for taking group differentiation considerations into account in post-disaster recovery resource allocation practices. [ABSTRACT FROM AUTHOR]

Empirical methods are commonly employed to predict the PGA distribution of an earthquake and are widely used. However, current empirical methods assume the seismic source to be a point source, a line source, or a plane source, where the energy is concentrated and released uniformly. An empirical attenuation model of the near-field peak ground acceleration (PGA) was proposed that considers a nonuniform spatial distribution of seismic fault energy and its 3D scale. Then, this model was used to reconstruct the PGA distribution of the 2008 Wenchuan, China, Mw7.9 earthquake based on the data of a seismic fault model and ground acceleration records of the mainshock and aftershocks collected by seismic stations. The predicted PGA values show similar attenuation characteristics to the interpolated map of the PGA recorded by seismic stations. A comparison with the results of a finite-fault model developed by the USGS indicates that the proposed model can provide more details and give a more precise result in the near field. The analysis of landslides triggered by the Wenchuan earthquake demonstrates that the PGA distribution estimated by this model can be used to validate the findings of other researchers. [ABSTRACT FROM AUTHOR]

In this paper, synthetic aperture radar (SAR) data from ENVISAT ASAR ascending, descending and ALOS PALSAR ascending orbits are collected to investigate the coseismic displacements of the Mw 6.4 earthquake occurred in Gaize, Tibet on January 9, 2008 and the Mw 5.9 aftershock on January 16, 2008. Two interferometric phase analysis techniques, i.e., D-InSAR and multi-aperture InSAR, are employed to process the SAR data, with which the displacement measurements along three different line-of-sight (LOS) and three different azimuth directions are retrieved, respectively. Complete three-dimensional (3-D) coseismic displacement fields caused by the earthquake are then resolved by integrating the obtained LOS and azimuth displacement measurements with a weighted least squares adjustment, whose distributions are conformed to the two north-northeast trending northwest-dipping normal faults detected in previous studies. Ground subsidence and uplift are observed in the hanging wall and footwall of the main fault, respectively, and the subsidence reaches its maximum in the hanging wall of the second fault as a superimposed result of the Gaize earthquake and its aftershock. Anti-symmetric horizontal movements are also detected during the seismic events, which move inward in the focal region, but outward at the marginal. The left-lateral motions near the main fault indicate a small striking slip component caused by the Gaize earthquake. Finally, we discuss the potential of applying the derived spatially continuous 3-D displacement fields to determine the high-resolution 3-D strain fields of the Gaize earthquake, which provide important knowledge for assessing the source mechanism. [ABSTRACT FROM AUTHOR]

In the Three Gorges reservoir region, central China, seismic activity increased substantially after the reservoir impoundment in 2003 which continues till date. Previous studies show that these are reservoir-triggered earthquakes and various factors are responsible for the increase in seismic activity after the reservoir impoundment. However, these studies do not provide a comprehensive assessment of influence of reservoir water level variations on spatiotemporal distribution of earthquakes. In this study, we statistically analyze the influence of the water level variations on the increased seismic activity in the reservoir region for the period from May 2003 to April 2020, using the power spectrum and singular spectrum techniques. Our statistical analyses confirm the influence of long-term variations in the water level time series on the occurrence of earthquakes after the reservoir impoundment. The analysis also indicates a positive role of annual reservoir water level fluctuations in the total seismicity of the region. Depending on the cluster patterns and relationship with faults, the earthquakes of the Three Gorges reservoir region are divided into three seismic zones (A, B, and C). For zone C, both the power spectrum and singular spectrum analyses confirm the strong periodic influence of reservoir water level variations on the earthquakes. Increase in seismicity of zone B is only in the initial period but not in the later stages of water impoundment and our statistical analyses indicate that the seismicity of this zone is not directly related to the annual reservoir water level variations. This confirms the conjecture in the earlier studies that the seismicity of this zone is related to the collapse of coal mines present in the area in the initial stages of reservoir impoundment. For zone A, our statistical analyses do not show strong influence of the annual reservoir water level variations on the occurrence of earthquakes. We suggest that this is due to the contribution of various other factors along with reservoir impoundment in the occurrence of earthquakes in this zone, as also opined in some earlier studies. [ABSTRACT FROM AUTHOR]

Disastrous earthquakes brought extensive damage to rural houses not designed to resist seismic movements in China. So far, the paucity of nation-wide data on rural houses, especially on their structural features, has prevented a comprehensive national assessment of the earthquake vulnerability of rural areas. This paper estimates the proportion of rural houses in each of five different structural groups in county-level administration units in China with downscaling methods and assesses the seismic vulnerability of counties paying attention to the seismic intensity and social-economic characteristics of different areas. A housing damage index is constructed with the expected amount and ratio of damaged houses in earthquakes, based on which four vulnerability levels are specified for each county-level unit. The results show that highly vulnerable and vulnerable counties account for 7.9 % and 10.7 % of all, respectively. Based on the distribution of these counties, the critical factors of weakness in different regions, such as seismic intensity, housing quality and population density, are analyzed, and risk reduction strategies are discussed. [ABSTRACT FROM AUTHOR]

Earthquakes that occur in a mountainous region can trigger a mass of landslides (ETL), and these hazards can cause relatively heavy casualties. Compared with other evaluation models and methods, quantification theory I is a multivariate statistical approach that can simultaneously process qualitative and quantitative variables. On the basis of the ETL features and the influencing factors, in this paper, we select lithology, slope gradient, slope height, slope structure, distance to seismogenic fault, hanging wall/footwall of the seismogenic fault, and rock integrity, a total of seven impact factors, as the assessment index. By randomly selecting 128 single slopes in an intense seismic area as the samples, we develop an assessment model and apply it to investigate the regional stability of the Jushui River basin to prove its applicability. Moreover, this method calculates the factor weight; this can also prove the method through a comparison with the existing research results obtained using other methods. [ABSTRACT FROM AUTHOR]

Hundreds of thousands of landslides were triggered by the May 12, 2008, Mw 7.9 Wenchuan earthquake in China. A detailed inventory of landslides triggered by the earthquake was prepared based on geographic information systems and remote sensing technology. Visual interpretation of high-resolution satellite images and aerial photos taken pre- and post-earthquake and selected field investigation showed that at least 197,481 co-seismic landslides related to the earthquake were triggered throughout an area of approximately 110,000 km 2. These co-seismic landslides are delineated as individual solid polygons. The landslides cover a total area of approximately 1,160 km 2. Most of the landslides are distributed in an approximate ellipse area with a total area of approximately 44,031 km 2. In this paper, quantitative co-seismic landslide criteria for seismic intensity zonation were constructed based on the original “M 8.0 Wenchuan Earthquake Seismic Intensity Map” (MWESIM) and co-seismic landslide abundance analyses. These quantitative criteria, which correspond to landslide area percentages (LAP), indicate the percentage of the area affected by landslides in certain calculation windows and are listed as follows: Areas of LAP ≥70 % correspond to the XII intensity district; areas of 20 % ≤ LAP < 70 % correspond to the XI intensity district; areas of 1 % ≤ LAP < 5 % correspond to the IX intensity district; and areas of LAP <1 % correspond to the VIII and less-than-VIII intensity districts. The VII and greater-than-VII intensity districts of the original MWESIM, which constituted an area of approximately 123,832 km 2, were corrected based on the above quantitative criteria. The degrees of fit of the original and revised MWESIMs with the co-seismic landslides were 93.8 and 95.8 %, respectively, indicating a 2.0 % improvement. The quantitative criteria of the constructed earthquake-triggered landslides for seismic intensity zonation can provide a scientific reference, standard, and basis for seismic intensity zonation in other earthquake events, especially those occurring in mountainous areas. [ABSTRACT FROM AUTHOR]

The Wenchuan earthquake in 2008 has resulted in 50% of Guangyuan city facing recovery from different extents of damages. The massive reconstruction provides a good opportunity for Guangyuan city to response to the National Council's call for tackling climate change by developing a harmonised and low-carbon economy. However, there are many arguments about the definition of 'low carbon' and the framework that low-carbon development should follow. Low-carbon development in an economically least developed region such as Guangyuan would provide evidence and contribute to the discussion. The paper employs CO emissions as an environmental indicator in scenario analysis to investigate Guangyuan's future carbon performance in following the national call of reducing 40% of carbon intensity by 2020 and an alternative low-carbon development path. The results have demonstrated that a 'win-win' solution can be reached-keeping rapid economic growth while reducing CO emissions, however, only by addressing the 'correct' determining factors. Technology improvements and production structure changes have been identified as the key determining factors to affect both carbon intensity and CO emissions in the future. The two factors are also interdependent. Governmental policies should give appropriate guideline to address both factors but with strong emphasis on production structure decarbonisation in order to avoid the mistake of 'polluting first and deal with the pollution later' during the emission-intensive industrialisation processes that many western countries and China's coastal regions have followed. [ABSTRACT FROM AUTHOR]

On May 22, 2021, a 7.4 magnitude earthquake struck Maduo County (34.59° N, 98.34° E), Qinghai Province, China, with a focal depth of 17 km. The earthquake occurred near the northern boundary of the Bayan Har block. Two highway bridges, including the Yematan bridge, collapsed. Based on the analysis of the seismic damage characteristics of the Yematan bridge, a finite element model of a three-span simply supported girder bridge was established. Nonlinear analyses were performed using the bedrock wave at the bridge site during the earthquake and the seismic safety evaluation wave of the bridge as inputs to analyze the causes of seismic damage of the bridge. The results show that the large beam displacement owing to the velocity pulse and the low-frequency components of ground motion are the main causes of the bridge damage. [ABSTRACT FROM AUTHOR]

Relief supply warehouses are material warehouses built to cope with natural disasters and guarantee the supply of life necessities. Great earthquakes (with Ms ≥ 7) are overwhelming natural disasters beyond human control. The efficiency in rescuing earthquake victims depends on if the construction preparations of large relief supply warehouses have fully assessed the influence weights of the factors of large earthquake disasters. We innovatively proposes a method for selecting ideal site of relief supply warehouses in terms of seismic evaluation and the quantification of site selection criteria. We assess disaster-affected areas and screen the transport mode of relief supplies based on seismic prediction and remote sensing recognition, quantify and classify the site selection criteria of relief supply warehouses in China, and finally determine the ideal site. Taking a seismically-active region as a study case, we identify seven major disaster-affected areas, estimate the largest safe flight range (255 km) of a helicopter in post-earthquake transport of relief supplies, and pre-selecte 37 candidate sites. We suggest that the spatial distances between candidate sites and essential transport hubs (such as airports, railway stations, and highway entrances/exits) and the construction planning of the city are crucial indicators for the ideal site selection. [ABSTRACT FROM AUTHOR]

Detailed and accurate historical earthquake disaster data are an important basis for understanding the characteristics of earthquake disaster losses and for conducting research on earthquake disaster prevention strategies and post-earthquake emergency rescue work. Due to different project scopes and discrepancies in data accuracy, the currently available databases may contain errors such as missing data or data with low accuracies. In this study, we developed the Mainland China Composite Earthquake causing Casualties Database (MCCEC-DAT), which contains 252 historical earthquake records that span from 1966 to 2021. The database contains earthquake attribute information (earthquake time, location, epicenter latitude and longitude, focal depth, epicentral intensity, etc.), loss information (number of deaths and injuries, building damage ratio, economic loss, cause of death, etc.), and socioeconomic data (population, population density, area of each zone of seismic intensity, mortality rate, etc.). This database also contains the lethality levels generated by this study. These levels are the result of the quantitative evaluation of the overall characteristic levels of the earthquake area. Furthermore, this metric permits the direct comparison of different spatial locations. Based on the results of the statistical analysis, this work shows that the distribution of historical earthquakes in mainland China has obvious spatial and temporal characteristics. Events are mainly distributed throughout the southwest region, and the magnitudes of those events are relatively diverse. The mortality rate is significantly correlated with the building damage ratio and the lethality level. The lethality level can not only facilitate an improved understanding of the comprehensive level of historical earthquake regions, but this metric also provides a quantitative foundation for the comparative analysis of earthquakes between different regions. Furthermore, the database can also provide a foundation for future research, such as research into assessing the loss from earthquake disasters. [ABSTRACT FROM AUTHOR]

Many counties in southwestern China were devastated by the Wenchuan earthquake, and this earthquake also induced several geological hazards. Therefore, evaluation of the eco-geological environment in the disaster area is essential for county restoration and ecological remediation. This research considers Pingwu County, which is located 89 km from the epicenter of the Wenchuan earthquake, as the study area to evaluate the eco-geological environment carrying capacity. First, three evaluation index layers are built for an eco-geological environment carrying capacity model after the earthquake, including the geological, ecological and social environments. Then, the evolutionary algorithm is used to modify the analytic hierarchy process (AHP). By optimizing the consistency ratio of the AHP, the most consistent evaluation matrix can be obtained. Finally, we calculate the eco-geological environment carrying capacity in Pingwu via the best consistent evaluation matrix and obtain a hierarchical map of the eco-geological environment carrying capacity through grid rasterization. The results indicate that the current eco-geological environment carrying capacity in Pingwu County mainly contains two states, equilibrium and surplus states. According to the hierarchical map, this study suggests that focusing on ecological protection and disaster monitoring in the eastern and northern areas of Pingwu, large infrastructures should be built in the central and southern areas, and the land use capability should be further improved. Moreover, construction in the central area of Pingwu should be optimized, the scale of regional construction should be controlled, and the original ecological species in the natural protection area should be maintained. [ABSTRACT FROM AUTHOR]

The largest earthquake (Ms 8½) in eastern China occurred near Tancheng in 1668. Six M ≥ 6 earthquakes occurred in this region in historical time. We re-examine the primary historical archives from this region, adding independent constraints such as maps of active faults, local topography, intensity attenuation laws for China, and relevant administrative practices in archiving data, to reassess source parameters (epicenter, magnitude, or maximum intensity). We use the seismic density index—a measure of the clustering of seismicity weighted by source magnitude—to identify candidate zones of present-day clustering of seismicity than may represent a long-term memory of past historical events in an intraplate setting. We update at least one of the source parameters for four of the seven events. The main shock and two aftershocks of the 1668–1672 Ms 8½ Tancheng earthquake sequence locate along the strike of the Tan-Lu fault zone, each associated with significant and contiguous seismic density anomalies whose elliptical contours are elongated along its strike. A third major aftershock (Ms ≈ 6) in this sequence locates some 200 km away from the fault zone. Six of the seven historical events have seismic density anomalies that cannot be explained by aftershocks of modern seismicity (ML ≤ 5.3), and hence are candidate zones for long-lived aftershock sequences. In contrast, there are no significant seismic density anomalies along the section of Tan-Lu fault south of Suqian, despite palaeo-seismic evidence for a Ms 8½ earthquake around 6280 B.C., providing an upper bound to long-term memory of great earthquakes in this region. [ABSTRACT FROM AUTHOR]

Soil-rock mixed accumulation bodies produced by rainfall, earthquake or early landslides tend to have unconsolidated structure and poor stability, and are prone to failure under the rainfall or earthquake. The Jiuzhaigou earthquake occurred in China on August 8, 2017, caused a lot of soil-rock mixed accumulation bodies on the slope, which seriously threatened the safety of people's lives and property. Earthquakes occur frequently in this area, so it is very important to analyze the instability and movement characteristics of the soil-rock mixed accumulation bodies under earthquake. In order to overcome the shortcomings of single numerical simulation method in simulating large-scale landslide, the discrete–continuous coupled approach is adopted, in which the discrete and continuous models are established to simulate the bedrock and sliding accumulation body, respectively. The results show that it is suitable for simulating the earthquake-induced accumulation body sliding movement. Under the seismic signal, cracks firstly appear in the back edge of the upper accumulation body, and then, the collapse occurs. The sliding body pushes the lower accumulation body to be unsteady and sliding, and finally, the sliding body accumulates at the foot of the slope. The average velocity and displacement of the rock blocks are greater than that of the soil during the movement. [ABSTRACT FROM AUTHOR]

Since the impoundment of the Three Gorges Reservoir (TGR) in the year 2003 in central China, the region is experiencing enhanced seismic activity. The enhanced seismicity after the TGR impoundment has been reported to be associated with several factors, e.g., Karst collapse, mine collapse, chemical effects due to water percolation, and reservoir-assisted shear failure on the mapped and seismological faults. Here in this article, we explore in detail the role of reservoir impoundment in mobilizing the nearby faults leading to increase in post-impoundment seismicity of the region. For this purpose, reservoir induced stress, pore pressure and their influence on subsurface faults, in terms of fault stability, are calculated to explore the role of TGR in inducing shear failure on the earthquake causative faults. Our analysis suggests that some of the areas of enhanced post-impoundment seismicity can be explained by the shear failure due to the reservoir impoundment. But a large region, despite being under the unfavourable influence of reservoir induced stress, also exhibit enhanced post-impoundment seismicity. Even the pore pressure due to the reservoir impoundment is not enough to mobilize these faults in these unfavourable regions. An extremely high pore pressure or some other mechanism, involving fluid interaction with rock mass due to the reservoir impoundment, is required to explain the enhanced seismicity in such regions. We suggest that dissolution and reduced cohesion in the Karst–Carbonate rocks present in the region also assisted in the enhancement of the post-impoundment seismicity. These post-impoundment earthquakes may be termed as fluid-assisted earthquakes in the TGR region rather than earthquakes linked with reservoir induced shear failure. Further, some of the post-impoundment earthquakes of relatively large magnitude which occurred in the region of pre-impoundment seismicity could be purely tectonic in nature and not influenced by the reservoir impoundment. Thus, we suggest that along with the TGR induced shear failure, various other factors also play significant role in the increase of post-impoundment seismicity. [ABSTRACT FROM AUTHOR]

Earthquakes result in overwhelming demand for medical resources at once, and affected areas requires reinforcement from neighbor cities. An effective allocation approach of medical rescue teams in early stage of disaster relief can improve rescue performance significantly. To find optimal allocation strategy, an integer nonlinear programming model is established, following utility principle. To construct the optimization model, stochastic transition probability of triage levels is introduced. Meanwhile, function from allocation scheme to fatalities of areas is established. Next, we design algorithm based on Lingo software to find solution of utility model. Finally, numerical experiments based on real data in 2008 Sichuan earthquake in China are used to compare utility approach with existing approaches in practice. The results of experiments indicate that: (1) to save more lives, a support team should preferentially be allocated to a worse and nearer affected area. When the worst area is not the nearest, the team also may be sent to an area with moderate severity and moderate distance. (2) Compared with severity strategy and distance strategy, utility strategy improves rescue efficiency significantly. [ABSTRACT FROM AUTHOR]

In urban area, popular and property is accumulated in a small area, potential risk of earthquake disaster in urban community is great. Pre-disaster emergency evacuation zoning has become a significant topic of disaster prevention and mitigation research. Based on the present layout of evacuation facilities and shelters as well as the evacuation demands in urban communities, a systematical methodology for occupant evacuation against earthquakes on community scale was developed by employing spatial analysis techniques of Geographical Information System (GIS). The methodology included the following aspects: the distribution analysis of emergency evacuation demands, the calculation of shelter space accessibility, and the optimization of evacuation destinations. This methodology was applied to Lujiazui Street in Pudong, a new district located in Shanghai, China. It was found that the proposed methodology could be used to formulate pre-event planning for earthquake disaster prevention and mitigation on a community scale, especially for organizing a rapid and smooth evacuation and optimizing the location allocation of shelters. [ABSTRACT FROM AUTHOR]

Earthquake preparedness can reduce casualties and economic losses caused by earthquakes effectively. Existing literature confirms that people's knowledge and perception of earthquakes can affect their actions concerning earthquake preparedness greatly. However, studies have mostly focused on developed countries. Meanwhile, China, particularly its rural regions, has been neglected. In addressing this deficiency, this study examines 5 counties and 10 villages that were seriously affected by the 2008 Wenchuan (Sichuan) earthquake. Using an on-site survey of residents, earthquake perceptions and their impact on disaster preparedness behavior were examined empirically. Exploratory factor analysis and random-effect logistic regression analysis were used. The results reveal that two factors considerably influence disaster preparedness behavior. First, residents with autonomous earthquake information access tend to be more prepared. Second, residents who are more sensitive about earthquakes (high perceived risk of occurrence) tend to be more prepared for earthquakes. Evidently, knowledge and awareness of earthquakes have a positive impact on the disaster preparedness of residents living in rural earthquake-prone regions. Consequently, government agencies should enhance the earthquake education of local residents as part of the national effort to mitigate the adverse effects of future earthquakes. [ABSTRACT FROM AUTHOR]

This article explores the spatial differentiation and integration between the post-disaster victims and the indigenous peasants 8 years after a rapid off-site resettlement oriented by governments in New Beichuan. Data were broadly collected from placement documents, questionnaires, interviews and site measurement by empirical research and on-site investigation in 2014. The resettlement plan was introduced and analyzed for housing resettlement, open space systems, public facilities allocation and resettlement policies. Based on statistical analysis of the questionnaire data and observation on the usage of the built environment, problems with the spatial usage and mismatches between the specific spatial requirements and subjective planning intention of integration are analyzed and preliminary findings are shown. The results showed that the excessive pursuit of speed and deficiency in economically self-sustaining efforts might contribute to insufficient attention given to spatial, social and economic aspects and leads to inevitable and long-standing problems, such as housing quality problems, neighborhoods management and security concerns, contradictions between the housing layout and local living habits, different spatial usage preferences between the indigenous peasants and post-disaster migrants, and disequilibrium of public facility allocation. [ABSTRACT FROM AUTHOR]

Most disaster research has focused on business recovery at a point in time or over a short period of time, with the goal of summarizing the experience to reduce business vulnerability in future disasters. However, studies on long-term business recovery processes may be more useful for providing lessons that support sustained business operations after a disaster. This study considers the changes in business' operating statuses following the initial survival of a large earthquake and examines how different factors influence sustained business operations during the long-term recovery after a disaster. The study uses logistic regression techniques along with field investigations and questionnaire data collected from 256 New Beichuan businesses that remained open following the 2008 Wenchuan earthquake in China. The study results showed that some of the original surviving businesses closed during the subsequent post-disaster operation process. As such, identifying businesses reopening after the disaster cannot be equated with long-term recovery. Factors significantly influencing the sustained operation of a business after the Wenchuan earthquake included: pre-disaster financial conditions, post-disaster monthly average profit, borrowing of money from family or friends, the business owner's gender, and government subsidies. Study findings have important theoretical implications for research on the long-term recovery of businesses after an earthquake. Findings also have practical value for business owners selecting post-disaster sustainable operation strategies. [ABSTRACT FROM AUTHOR]

An improved stochastic finite-fault method was used to simulate the Mw 6.6 earthquake that occurred on August 8, 2017, in Jiuzhaigou, Sichuan, China. A variation of the stochastic finite-fault method, considering the dynamic corner frequency, was used to overcome the corner frequency. It explains the effect of a given slip distribution on the corner frequency of each subfault. A comparison of the response spectra (damping ratio 5%), spectral ratio (simulated values/observed values), and model deviation demonstrated that the improved corner frequency performs well for the whole periods, especially in short periods from 0.2 to 1 s. Similarly, the revised duration model and the site-amplification factor were applied to simulate the ground motion during the Jiuzhaigou earthquake, and then the response spectra were obtained. The duration of the nine near-field station recordings matched well with the simulated ground motions, and the peak ground acceleration (PGA) of most of the stations matched well with the observed PGA. In the short periods (T < 1 s), a small difference is observed between the simulated response spectra and the observed spectra for most of the stations. However, the response spectra were overestimated within the period range (0.05–10 s). Generally, the simulated ground motions obtained by using the improved model matched well with the observed ground motions, which could be considered the basis for earthquake-resistant design during the postdisaster recovery and the structural dynamic analysis of the Jiuzhaigou region. [ABSTRACT FROM AUTHOR]

Light rain or moderate rain is the most common meteorological event in the rainy season in the loess area of China, so the probability of landslide hazards induced by the coupling effect of earthquakes and rainfall under the condition of light rain or moderate rain is relatively higher than that under heavy rain. To study the dynamic response characteristics and instability mechanism of loess slopes by the coupling effect of earthquakes and rainfall under the conditions of moderate rain and light rain, a low-angle slope model test of a large-scale shaking table after 10 mm of rainfall was carried out. By gradually increasing the dynamic loading, the evolution of the macroscopic deformation and the instability failure mode of the slope model are observed; the temporal and spatial trends of the amplification effect, acceleration spectrum, pore pressure and soil pressure are analyzed; and the failure mechanism of the slope is determined. The results showed that the amplification effect increased along the slope surface upward, and a strong amplification effect appeared at the front of the top of the slope. Because of the stronger dynamic stress action on the upper part of the slope, the immersed soil in the upper part of the slope experienced seismic subsidence deformation, the saturation in the seismic subsidence soil increased, and the water content temporarily increased locally. With the further increase in the loading intensity, a large number of tension cracks were generated in the seismic subsidence area, and water infiltrated down along the cracks and the wetting range expanded under dynamic action. The range of seismic subsidence and cracks further extended to the deep part of the slope. Under the reciprocating action of the subsequent ground motion, the swing amplitude of the soil mass in the seismic subsidence area, which is divided by a large number of cracks in the upper part of the slope, increased further, resulting in the further reduction in the residual strength of the seismic subsidence soil mass located at the crack tip due to the pull and shear action. Finally, under the combined action of gravity and dynamic force, the upper soil mass in the seismic subsidence area dragged the lower soil mass in the seismic subsidence area downward because the sliding force is greater than the residual strength of the soil mass, which induced a seismic subsidence-type loess landslide. Under the coupling effect of earthquakes and rainfall, the instability mode and mechanism of this landslide are significantly different from those of liquefaction-type landslides. [ABSTRACT FROM AUTHOR]

The Ya'an, Sichuan Mw 6.7 earthquake occurred on April 20, 2013. In this article, the stochastic finite-fault method (EXSIM) based on dynamic corner frequency, proposed by Motazedian and Atkinson (Bull Seismol Soc Am 95(3):995–1010, 2005), is validated to be an intelligible and productive approach for the generation of high-frequency strong ground motion. The validated model parameters were considered for the simulation at 31 selected stations, which are less than 200 km away from the fault. The input parameters included site condition, source term, and path term. The calibration of the input parameters, such as the stress drop, was achieved by using misfit functions between the observed PSA (pseudo-acceleration response spectra) and simulated PSA in the time domain. Some of the other parameters, such as distance-dependent duration, high-frequency attenuation parameter kappa, and local amplification functions, were calibrated by considering the observed recordings. In this study, we attempted to employ two different slip models for strong ground motion simulation, so that the influence on the simulation results can be revealed. Our results depicted that although the method cannot combine well, the directivity effects and the soil conditions are not adequately represented at individual stations, the synthetics satisfactorily match with the seismic characteristics regarding peak ground acceleration (PGA), response spectra, Fourier spectrum, and time history, for both the time and frequency range considered. The results also demonstrated that there is a slight difference between the simulation results of the two slip models. Finally, we compared the effects of different distance-dependent duration models for the simulated PGA. It illustrates that it is difficult to find a balance between the ground motion duration and PGA at stations with fault distance less than 20 km, which makes the duration and PGA to coincide well with the observed recordings. [ABSTRACT FROM AUTHOR]

By using a questionnaire survey and performing a case study in the Yushu Tibetan Autonomous Prefecture, this study examined the similarities and differences between the perceptions of local practitioners and the perceptions of experts regarding the priority of the factors affecting earthquake emergency response and rescue at the county level in China. The results show that the perceptions of the most and the least important factors are similar between the two groups, except for the factors that affect special abilities. However, one first-level factor, i.e., environmental conditions, and 16 second-level factors, e.g., influence of ethnic cultures, professional rescue teams, GDP level and historical earthquake disaster experience, significantly differed. The local realities of the natural geography, socioeconomic conditions (e.g., economic level, education and ethnic), earthquake experiences and knowledge form the perception of local practitioners, whereas the experts' perceptions are more consistent with their social role, emergency experiences and knowledge, especially in disaster-prone areas, influencing the differences between the two groups. Suggestions regarding the incorporation local perceptions into the development of local emergency capabilities rather than merely following the perception of experts are discussed. [ABSTRACT FROM AUTHOR]

The April 20, 2013 Mw6.6 earthquake of Lushan County, Sichuan Province, China, has triggered 4540 landslides (> 1000 m2). Exploring a more effective method to assess landslide hazard in the affected area of this event is of great significance for disaster prevention and mitigation. By applying the Newmark model and two statistical analysis models (logic regression and support vector machine, LR and SVM), this study addressed this issue. In the Newmark model, we used the landslide point density, the average gradient (mean slope) and the mean peak ground acceleration to group the lithology and created a critical acceleration (ac) map. The Newmark displacements and the probability of the slope instability are mapped by combining the ac map and PGA map. In the statistical analysis models of LR and SVM, 7040 samples (4540 landslide sites and 2500 random non-landslide sites) were randomly divided into the training set (5000 samples) and validation set (2040 samples). Based on the relationship between landslide distribution and influence factors, we selected the critical acceleration (ac) value, topographic relief, PGA, and distance to rivers as the independent variables for LR and SVM. Finally, the ROC curves for three landslide hazard models were drawn and the AUC values were calculated. The landslide hazard maps produced by LR are similar to those by applying SVM. The AUC values indicate that these two models combined with ac data perform better than the simplified Newmark model. In this study, a new method of integrating statistical analysis models (LR and SVM) with critical acceleration (ac) for earthquake landslide hazard assessment is presented, which can be used to carry out seismic landslide hazard assessment more effectively than the simplified Newmark model. [ABSTRACT FROM AUTHOR]

Tsunami disasters have been documented several times in Chinese history, mostly in the Taiwan region. To assess the tsunami hazard along the coast of mainland China from sources in Taiwan, this study analyzed historical tsunamis and undersea seismic events around Taiwan and found that the frequency and magnitude of earthquakes around Taiwan are significantly higher than in the adjacent Ryukyu and Manila trenches. The probabilistic seismic hazard analysis method was adopted to estimate the maximum possible earthquake magnitude around Taiwan. Then, six tsunami sources were assumed in those places where both earthquakes and tsunamis have occurred previously. Numerical models of the tsunamis were used to calculate the probable maximum tsunami amplitude and tsunami arrival time. The largest tsunami amplitude and the shortest arrival time were drawn on a GIS map. The modeling results provided a summary of tsunami hazards along the coast of mainland China from tsunami sources in Taiwan. The results showed that tsunamis triggered by the maximum possible earthquakes in the Taiwan region would arrive first at Zhejiang, Fujian, Guangdong, and Hainan Provinces within 3 h; the largest tsunami amplitude was up to 3.3 m. Thus, parts of Zhejiang, Fujian, and Guangdong Provinces were identified as regions with the highest hazard levels. [ABSTRACT FROM AUTHOR]

Mega-disasters appeared in the twenty-first century highlighted the importance of strengthening local disaster management capabilities to cope with risks more effectively. Despite the occurrence of Wenchuan (2008) and Lushan (2013) earthquakes, local capacities in managing disaster in China remained largely unexplored. Given the scant empirical attention given to township level, we focus our study on assessing the disaster management capacities through seven indicators in the affected townships of Wenchuan (2008) and Lushan (2013). After interviewing 32 townships executives, the finding suggests that although substantial progress has been achieved in strengthening the overall disaster management capacity in townships by 2013, pronounced challenges remained. We argue that the restrained disaster management capacity in Chinese townships was attributed to three factors. First, the top-down institutional framework has limited the autonomy of township governments from ensuring disaster-related policy to be executed effectively as it induced a shortage of funds and undermined incentives for officials to enforce policies. Second, the failure of township governments to pursue external collaboration with local and social organizations has impeded the mainstreaming of key disaster management components into local level. Finally, national development strategies, and the by-product of rapid urbanization processes, have caused the lack of human resources that prevented effective mechanisms of disaster preparedness and responses as well as post-disaster reconstruction from developing. [ABSTRACT FROM AUTHOR]

Earthquake emergency response and rescue (ERR) is a global challenge, but especially in developing countries. As a large earthquake-prone developing country, China's experiences and lessons in ERR can provide a useful reference for other developing countries. In this article, China's ERR progress is summarized by comparatively analyzing the Wenchuan and Lushan earthquakes, two major recent earthquake events in Sichuan Province. From a comprehensive investigation of the research, it can be concluded that emergency response speed, inter-organizational coordination, and relief resource mobilization are the three critical ERR indicators which can be further subdivided into sixteen sub-indicators. Using these indicators, the Wenchuan and Lushan earthquake ERR processes were comprehensively compared based on data collected from observations and interviews. The results showed that the response and rescue efforts at the Lushan earthquake were faster, more coordinated, and more orderly than those at the Wenchuan earthquake. In addition, the unified earthquake ERR system, the people-oriented principle, and the information disclosure mechanism were examined, which also revealed several major shortcomings, such as deficits in the adaptability to relief technologies, the lack of coordination between rescue organizations, and the lack of capabilities in the local communities. Finally, several recommendations are given for the practical improvement of and future research into the establishment of an effective ERR. [ABSTRACT FROM AUTHOR]

China has a long history of earthquake records. The Shanxi rift system (SRS) is situated along the axial zone of the domal uplift of the Shanxi Highlands and is the boundary between the Ordos block and the North China Plain block. Strong earthquakes in the SRS have been recorded since the thirteenth century. In our work, we applied the Bayesian probability method using extreme value distribution of earthquake occurrences to estimate the seismic hazard in the SRS. The seismic moment, slip rate, earthquake recurrence rate, and magnitude were considered as the basic parameters for computing the Bayesian prior estimates of the seismicity. These estimates were then updated in terms of Bayes' theorem and historical estimates of seismicity in the SRS. The probability of occurrence of $$M_{\text{s}} = 5.0$$ for Z1, Z2, and Z3 is less than 0.3, 0.1, and 0.6, respectively ( T = 5 years). The probability of the occurrence of M $$\ge$$ 8.0 is small for the whole SRS. The selection of upper bound magnitude probably influences the result, and the upper bound magnitude of Z1, Z2, and Z3 may be 7.5, 7.0, and 8.5, respectively. We obtained the values of the magnitude of completeness M (3.2) and the Gutenberg-Richter b value before applying the Bayesian extreme value distribution of earthquake occurrences method. [ABSTRACT FROM AUTHOR]

The article discusses impacts of occurrence of an earthquake of 7.0 magnitude struck China in Lushan County of Ya'an, Sichuan Province in China. According to the Sichuan Provincial Department of Civil Affairs, approximately 718,000 housing units, transportation facilities and 224 power lines were damaged in the earthquake. It also informs that Chinese President Xi Jinping and Premier Li Keqiang had announced to take possible measures to rescue the victims just after the incident.

Housing reconstruction is always the top priority issue in post-disaster reconstruction of rural areas in developing countries. However, the traditional reconstruction approaches, including reconstruction in situ, and resettlement are not sustainable enough for post-disaster reconstruction. Against the dispersion pattern of settlement, this study argues that developing concentrated rural settlement is able to increase the resilience of rural villages and to provide a basis for sustainable development post-disaster. Little study has reported developing concentrated rural settlement in post-disaster reconstruction until the reconstruction post 5.12 Sichuan Earthquake. Yet, there is still an unclear understanding of the factors taken into account when developing concentrated rural settlement in post-disaster reconstruction. This study aims to explore the critical determinant factors to be considered for developing concentrated rural settlement in post-disaster reconstruction with particular reference to the reconstruction post of 5.12 Sichuan Earthquake in China. Through content analysis, a preliminary list of determinant factors was firstly identified. Interviews with the local government officers, planners, and rural victims were conducted to collect opinions on the critical factors. It was found that governmental guidance, victims' willingness, and economic development condition are three critical dimensions. The findings from this research can help understand the preconditions for developing concentrated rural settlement in post-disaster reconstruction and promote this approach in future. [ABSTRACT FROM AUTHOR]

We collected and analyzed 68 civilian monitoring videos recording the scenes of the May 12, 2008, Wenchuan earthquake. These video recordings are shared online by volunteers after the earthquake. Intensity was estimated by visual inspection of the playback video recordings. Comparing to traditional media accounts, these video records have the distinctive unbiased feature in obtaining local intensity due to their dynamic and repeatable nature. We argue that with proper guidance for providing the necessary information of the location and time when sharing these data online, civilian monitoring videos are potentially more and more useful in the citizen-powered macro-seismology. [ABSTRACT FROM AUTHOR]

The 2008 Wenchuan earthquake induced a large number of landslides, and a vast amount of loose landslide materials deposited on steep hill slopes or in channels. Such loose materials can become sources of deadly debris flows once triggered by storms. On 13 August 2010, a storm swept Yingxiu and its vicinity, triggering a catastrophic debris flow with a volume of 1.17 million m in Xiaojiagou Ravine. The debris flow buried 1,100 m of road, blocked a river and formed a debris flow barrier lake. A detailed field study was conducted to understand the initiation mechanisms and runout characteristics of this debris flow. Two types of debris flows are identified, namely hill-slope debris flow and channelized debris flow. The hill-slope debris flow was triggered in the forms of firehose effect, rilling and landsliding, whereas the channelized debris flow was triggered in the form of channel-bed failure. This debris flow was a water-rock flow since most particles were gravel, cobble or larger rocks and the fraction of silt and clay was less than 2%. Grain contact friction, pore-pressure effects and inertial grain collision were the three most important physical interactions within the debris flow. Such interactions yielded a smaller runout distance (593 m) compared with those of mud-rock flows of similar size. [ABSTRACT FROM AUTHOR]