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Tsunami inundation maps are crucial for understanding the impact of tsunamis and planning mitigation measures. Our research focuses on creating a database of stochastic tsunami scenarios along the Chilean subduction zone and probabilistic inundation maps for 11 coastal cities. We divided the Chile-Perú subduction zone into four seismic segments based on historical seismicity. Stochastic rupture scenarios, ranging from 8.0 to 9.6 magnitudes, were generated using the Karhunen-Loeve expansion. The Stochastic Reduced Order Model (SROM) helped select representative tsunami scenarios for each segment and magnitude bin. We then used the NEOWAVE model to simulate these scenarios to an inundation level, creating probabilistic tsunami maps for various return periods. Our findings reveal that local geography significantly influences tsunami inundation, with some areas facing high inundation risks while others experience minimal impacts. As a result, a uniform planning and design criterion across the entire country is not advisable; site-specific studies are necessary. These probabilistic scenarios can provide tailored solutions for different Chilean coastal cities, enhancing their resilience. Additionally, this research marks the first comprehensive probabilistic tsunami hazard analysis for the Chilean coast, considering multiple seismic sources, marking a crucial step toward full tsunami risk assessment for coastal communities. [ABSTRACT FROM AUTHOR]

Lake Tennyson's basin and sedimentary record were assessed for multiple branches of paleoenvironmental research. A geophysical investigation of the lake depositional setting was supported by physical and chemical analysis of multiple sediment cores. The basin reaches 60 m depth and several subaerial landforms identified were likely deposited from seismic activity. Deformed sediments and turbidites in gravity cores are attributed to one or more large (pre)historic earthquakes, and episodic grain size changes in sediment cores are related to either seismic and/or climatic/meteorological processes. A hummocky slump deposit located on the western lake bed margin is linked to widespread sediment deformation that was likely caused by movement of the Awatere Fault. Radiocarbon dating constrains the most recent major deformation event between the late thirteenth century CE and mid-twentieth Century. Folded turbidites in the stratigraphy suggest multiple sedimentary deformation episodes occurred during the last millennium. Micro-XRF elemental signatures suggest proxies of past water column mixing (windiness proxy) can be reconstructed via identification of changing redox conditions. Records from Lake Tennyson show potential for several palaeoenvironmental research applications, and combining them with basin morphostratigraphy and land-based palaeoclimate and palaeoseismic evidence can enhance understanding of environmental change in the northern South Island. [ABSTRACT FROM AUTHOR]

The ongoing Indo-Eurasian convergence leads to great megathrust earthquakes in the Himalayan region, affecting the life and infrastructure of the world’s most densely populated areas adjoining the Himalaya. The ~2500-km long Himalayan arc has experienced several earthquakes having magnitude greater than Mw 7.5 during the last millennium. While palaeoseismic and fault slip-rate studies have gained pace during the last few decades in the Western and Central Himalayan regions, the Eastern Himalaya and contiguous regions remain understudied. Even though geological evidence of great earthquakes in 1697, 1714, and 1950 CE has been reported in the Eastern Himalaya, the lateral extent of their rupture is still debated due to limited and sparse palaeoseismic studies. Furthermore, the segmentation of the eastern Himalaya raises concerns about the role of sub-surface transverse structures in controlling the rupture propagation of large to great earthquakes. Hence, we have compiled all the palaeo-earthquake studies carried out in the eastern part of the Himalayan convergent plate margin of the Indian Subcontinent and identified the potential gap areas with the slip deficit, which are capable of generating Mw > 8 earthquakes in the future. This study aims to provide a foundation for future palaeo-earthquake studies, which are crucial in understanding the earthquake recurrence and the strain release pattern in the region. [ABSTRACT FROM AUTHOR]

Shrinking of intermontane basins and expansion of their flanking ranges by reverse faulting and backthrusting in two counter-dipping systems is a typical mechanism of crustal shortening and mountain building in Central Asia. This mechanism is realized along the Kurai Fault Zone (southeastern Gorny Altai). Motions on two reverse fault systems maintained thrusting of the Kurai Range and the Kubadru Uplift on the Kurai Basin sediments and caused the growth of a foreberg before the mountain front. Forberg separates narrow Aktash Basin from the Kurai Basin. The paleoearthquakes were generated by reverse faults that delineate the foreberg. Analysis of the QuickBird satellite images, drone imagery, trenching, archaeoseismological research, radiocarbon dating, dendrochronology, and previous results show that eleven large (МW = 6.5–7.6) paleoearthquakes left traces as surface ruptures along the Kurai Fault Zone: twice before 7.5 ka BP, three events between 7.5 and 5.9 ka BP (7.0, 6.3, and 5.9–5.8 ka BP), one from 5.8 to 4.6 ka BP, four more at 4.6, 3.2, 1.5, and 1.3–1.2 ka BP, and the ultimate earthquake no older than 1450–1650 AD. The time difference between large earthquakes was from 200 to 1700 years. Surface faulting occurred mainly along the northern border of the foreberg where fault scarps are progressively younger northward and the Cenozoic sediments of the Aktash Basin thus become involved into uplift. GPR data to a depth of 12 m confirm the complex structure and slip geometry of the observed surface ruptures. The fault scarps are located < 1 km from the planned route of the gas pipeline from Russia to China, and the potential seismic hazard has to be taken into account in its design and construction. [ABSTRACT FROM AUTHOR]

Both surface motion and hole stress concentration have always been concerned in engineering design. In this paper, a theoretical approach is used to study the scattering problem of circular cavities under a non-symmetrical V-shaped canyon. The wave displacement function is obtained by solving the Helmholtz equation that meets the zero-stress boundary conditions by adopting the method of separation of variables and the symmetric method. Based on the complex function method, multi-polar coordinate method and region-matching technique, algebraic equations are established at relevant conditions, which include auxiliary and free boundary conditions. Then, according to sample statistics, a least-square method is used instead of the Fourier expansion method to solve the undetermined coefficients of the algebraic equations by discrete boundary. Numerical results show that the theoretical method is verified valid by the finite element method and the reduced model, and the displacement of the free surface and the stress of the circular cavity are related to the shape of the canyon, the position of the circular cavity, the direction of the incident wave and the frequency content of the excitation. [ABSTRACT FROM AUTHOR]

In this paper, we consider a generalized seismic Radon transform that maps a given function to its integrals over a certain family of curves in the plane. Such transforms arise in many areas of mathematics, geophysics, and imaging science. This paper contains new explicit inversion formulas of this generalized seismic Radon transform for various families of curves based on their monotonicity. We derive an analogue of the Fourier slice theorem and present a Sobolev space to obtain a stability estimate for this Radon transform. Finally, we consider local uniqueness results for which we prove a sufficiency theorem. [ABSTRACT FROM AUTHOR]

The Renewal Epidemic-Type Aftershock Sequence (RETAS) model is a recently proposed point process model that can fit event sequences such as earthquakes better than preexisting models. Evaluating the log-likelihood function and directly maximizing it has been shown to be a viable approach to obtain the maximum likelihood estimator (MLE) of the RETAS model. However, the direct likelihood maximization suffers from numerical issues such as premature termination of parameter searching and sensitivity to the initial value. In this work, we propose to use the Expectation-Maximization (EM) algorithm as a numerically more stable alternative to obtain the MLE of the RETAS model. We propose two choices of the latent variables, leading to two variants of the EM algorithm. As well as deriving the conditional distribution of the latent variables given the observed data required in the E-step of each EM-cycle, we propose an approximation approach to speed up the E-step. The resulting approximate EM algorithms can obtain the MLE much faster without compromising on the accuracy of the solution. These newly developed EM algorithms are shown to perform well in simulation studies and are applied to an Italian earthquake catalog. for this article are available online. [ABSTRACT FROM AUTHOR]

Spectral transform, known as a curvelet, enables sparse representations of complex data. Denoising wave propagation in disordered media and pattern recognition are just a few of the numerous domains in which denoising has a potential application. Based on directional basis functions, this spectral method represents objects with discontinuities along a smooth curve. In this study, we used this technique to eliminate ground roll, an unwanted feature signal that can be seen in seismic data obtained by sonating the earth's geological formations. Additionally, we improved the curvelet transform threshold denoising method combined with a fast non-local mean to remove seismic random noise. First, cyclic translation and block complex domain threshold methods were introduced into the curvelet transform threshold denoising, and the traditional curvelet threshold denoising method was improved to obtain the best denoising results; Subsequently, the removed noise was filtered using a fast non-local mean method to obtain a valid signal. Finally, the data obtained in the above two steps were added to obtain the final denoising result. The results of the model tests and actual seismic data denoising showed that the denoising results obtained using this method had a higher signal-to-noise ratio and fidelity than that using the other methods. [ABSTRACT FROM AUTHOR]

In practical applications, microtremor data often encounter contamination from various sources of noise, leading to suboptimal processing outcomes. This study aimed to provide a comprehensive analysis of the impact of noise on the microtremor method. The focus was on presenting explicit and quantitative evidence to demonstrate the extent to which these noises influence the accuracy and reliability of the method. Initially, a ten-station triangular array was employed to gather a sequence of high-precision microtremor data. Next, various influencing factors, such as high-amplitude random noise, were generated and incorporated into the meticulously collected real data in order to simulate the actual perturbation process. Based on both the raw and the artificially contaminated data, a series of dispersion curves of the fundamental-mode Rayleigh waves were obtained by applying the extended spatial autocorrelation method (ESAC). Based on the obtained results, several valuable conclusions have been derived that can effectively inform the procedures for acquiring and processing microtremor data. If the amplitude and duration of sudden onset vibrations are considerable, more data should be collected to reduce the Negative impact. If non-random noise exhibits similar frequency characteristics as microtremor data, and the duration and energy of the noise are relatively small, it can be ignored; otherwise, more data should be collected. The dispersion curve, determined by the principle of the ESAC method, remains unaffected by any changes in the amplitude of one or more traces. The likelihood of frequency dispersion curve distortion increases as the impact of entire data anomalies on the coherence curve becomes greater. In general, when the collection positions of abnormal data are more widely spaced, the impact on the frequency dispersion curve tends to decrease. It is important to note that, in a nested-triangular array configuration, the central geophone plays a crucial role in ensuring accurate and dependable outcomes. [ABSTRACT FROM AUTHOR]

This research article presents an analysis of the behavior of an initially stressed monoclinic piezothermoelastic half-space based on memory-dependent three-phase lags heat transfer law (MPS) underlying a thermoelastic half-space (TS) with subject to the hyperbolic two-temperature (H2T), classical two-temperature (C2T), and without two-temperature (W2T) models. By applying the normal mode approach, calculate the amplitude ratios and further utilize them to obtain the waves' energy ratios and interaction energy. The effect of memory-dependent derivatives (MDD), initial stresses, various kernel functions, and two temperature factors on the variation of energy ratios with incidence angle are graphically shown. The findings of this study have the potential to optimize material design, enhance seismic imaging techniques, improve thermal management in machinery, develop renewable energy systems, and facilitate materials characterization across diverse industries. [ABSTRACT FROM AUTHOR]

We use new paleoseismic data and lidar to reassess late Quaternary activity of the NW (northwest) Cardrona Fault, a ∼60 km long range-bounding fault in Otago. Paleoseismic investigations of the NW Cardrona Fault were conducted in the 1980s, but findings were limited by a paucity of materials suitable for dating. Here, re-exposure and re-assessment of a 1980s trench at Macdonalds Creek provide stratigraphic evidence for two surface rupturing earthquakes on the NW Cardrona Fault. Through Optically Stimulated Luminescence dating and OxCal modelling, we estimate these earthquakes occurred at (mean ± 2 standard deviations, σ) 20.5 ± 7.8 ka and 8.7 ± 6.6 ka. The timings of these earthquakes are consistent with those proposed from re-interpretation of another 1980s trench on the NW Cardrona Fault in the Kawarau River valley, ∼25 km farther south. The slip rate and recurrence interval derived from the Macdonalds Creek trench data are 0.13 ± 0.05 mm/yr and 11,800 ± 5100 years (2σ error) respectively. These estimates imply lower slip rates and longer earthquake recurrence intervals on the NW Cardrona Fault than previously assessed. [ABSTRACT FROM AUTHOR]

In the 2017 translation of his article "France-Japan: The Coral Writers," Michaël Ferrier explores the concept of the coral writer, or écrivain du corail. Echoing Fabien Arribert-Narce (2021), this article initially identifies Ferrier himself as an écrivain du corail and expands this concept further as it unearths resonances between creolization and Ferrier's own writing. This article revisits a multimedia project from the 2022 Winthrop-King conference Tokyo Stories: Writing the World with Michaël Ferrier in order to demonstrate that mirroring Ferrier's unique style allows for participation in and promotion of creolization. Using content from the collaborative project entitled "Poétique de la déroute chez Michaël Ferrier : une approche mimétique du fragment" and created with doctoral candidate Carine Schermann, this brief commentary accentuates the unexpected but beneficial discoveries that await if one interprets the world in the style of Ferrier: writing "from the inside" (Ferrier, "France-Japan" 19) and composing seismographically (Ferrier, "L'écrivain sismographe" 96). [ABSTRACT FROM AUTHOR]

Can a P-wave detection algorithm enhance the performance of an Earthquake Early Warning System (EEWS), particularly in community-engaged networks of low-cost ground motion sensors susceptible to noise? If so, what P-wave detection algorithm would perform the best? This study analyses the performance of four different P-wave detection algorithms using a community-engaged Earthquake Early Warning (EEW) network. The ground motion data from a 48-hour time window around a M5.8 earthquake on 22 September 2022 were used as the basis for this case study, where false and missed detections were analysed for each P-wave detection algorithm. The results indicate that a wavelet transformation-based P-wave picker is the most suitable algorithm for detecting an earthquake with minimal missed and false detections for a community-engaged EEWS. Our results show that a citizen seismology-based EEWS is capable of detecting events of interest to EEW when selecting an appropriate earthquake detection algorithm. The study also suggests future research areas for community-engaged EEWSs, including dynamically changing P-wave detection thresholds and improving citizen seismologists’ user experience and involvement. [ABSTRACT FROM AUTHOR]

Reliable palaeoseismological data are crucial for understanding the rupture history and seismic hazard assessment of a specific seismogenic structure. Many large earthquakes occurred around the Ordos Block of northern China. However, due to insufficient age data and event interpretations, the rupture patterns of the block are still poorly known. This study focuses on the central section of the Serteng Shan fault that is situated at the north margin of the Ordos Block. We present palaeoseismic sequence of faults using trenches combined with dating methods, including optically stimulated luminescence and 14C dating. We collected eleven optically stimulated luminescence (OSL) and seven radiocarbon samples to constrain the timing of palaeoseismic events in the excavated trench exposures along the fault strand. The results show that the studied samples were deposited since the latest Pleistocene, and the ages are, within uncertainty, in the stratigraphic order. The cause of the most recent surface rupture is still not clear. Four other older events, which occurred in 3.1–3.9 ka, 5.8−6.5 ka, 10.8–13.1 ka, and 14.2–16.5 ka, likely extended at different lengths along the Serteng Shan fault. [ABSTRACT FROM AUTHOR]

The viscoelasticity of an underground medium will cause absorption and attenuation of seismic waves, resulting in energy attenuation and phase distortion. This absorption and attenuation is often quantified by the quality Factor Q. The strong attenuation effect resulting from geology is a challenging problem for high-resolution imaging. To compensate for the attenuation effect, it is necessary to estimate the attenuation parameters accurately. However, it is difficult to directly derive a heterogeneous attenuation Q model. This research letter proposes a method to derive a Q model from reflection seismic data using a backpropagation neural network (BPNN), one of the most widely used neural network models. We treated the Q detection problem as a pattern recognition task and train a network to assign the correct Q classes to a set of input patterns. The proposed method uses synthetic data for network training and validation. Finally, we used a set of model data and a set of field data to demonstrate the effectiveness of this method, and the high-resolution imaging results in the time domain with appropriate compensation are obtained. [ABSTRACT FROM AUTHOR]

The Hundalee Fault forms part of the southeastern margin of the 2016 Kaikōura Earthquake rupture zone. Its late Quaternary activity and structural character may offer insights to fault interrelationships associated with the 2016 rupture. Mapping of the Hundalee Fault revealed several pre-existing fault scarps. Trenching of a scarp across a fluvial terrace together with radiocarbon dating shows the occurrence of at least two, probably three, surface ruptures since 3.5 ka. The scarp records about 2.5 m of reverse-sense vertical deformation, mostly folding, of which ∼0.6 m occurred in 2016, along with subordinate sinistral slip. Fluvial terrace ages inferred from geomorphological relationships, together with the trenching results, indicate a long-term vertical slip rate of 0.2–0.4 mm/yr since at least 30 ka. Geological data indicate a relatively recently surface emergence of the Hundalee Fault from beneath a fault propagation fold. The 2016 Hundalee Fault rupture is interpreted as a break-out from an extensive blind thrust fault, whose motion triggered predominantly contractional rupture of an array of steeper near-surface faults. The thrust is hypothesised as having provided linkage in the 2016 rupture between the predominantly strike-slip ruptures of The Humps Fault to the southwest and the Kekerengu Fault to the northeast. [ABSTRACT FROM AUTHOR]

The 2016 MW 7.8 Kaikōura Earthquake nucleated on The Humps fault, which ruptured across the Emu Plain in North Canterbury. The paleoearthquake history of the fault was poorly constrained prior to the 2016 earthquake. To determine the timing and single-event displacements (SED) of earthquakes on the fault we use Optically Stimulated Luminescence (OSL) and radiocarbon dates of faulted stratigraphy and analysis of faulting (i.e. geometry and slip) at the McLean-1 trench site. At the trench the fault trace trends east–west and primarily accommodated right-lateral strike-slip in 2016 (2 ± 0.2 m strike slip and 0.35 ± 0.05 m vertical slip northside downthrow). The Humps fault is more seismically active than previously thought and accrued slip during at least six surface rupturing paleoearthquakes. The timing of these earthquakes was: 9.8–15.3 ka BP (Event 1), 8.6–11.5 ka BP (Event 2), 8.1–10.9 ka BP (Event 3), 6.0–8.6 ka BP (Event 4), 1840 AD to 4.5 ka (Event 5), and 2016 AD (Event 6). These earthquakes have a mean recurrence interval of 1.8–3.4 kyr and could have recurrence intervals up to ~9 kyr. Kaikōura-type ruptures could occur as frequently as every ∼2 kyr and maybe longer if The Humps fault rupture geometries are not characteristic. [ABSTRACT FROM AUTHOR]

The Kaikōura Earthquake ruptured a complex network of at least 20 faults in the northeastern South Island, with variable geometries, slip and slip rates. Ground shaking and surface fault rupture generated a tsunami, thousands of landslides, and many dammed rivers. The earthquake damaged farmland, buildings and infrastructure in the northeastern South Island and Wellington regions, closing critical transport networks for over a year. This special issue presents a collection of 12 papers on the earthquake. These papers cover a range of topics, including, the geometries and paleoearthquake histories of faults that ruptured, seismic hazards, the tsunami and coastal geomorphology, together with the societal impact and communication of the earthquake. They incorporate our understanding of the earthquake 5–6 years since it occurred. Despite an unprecedented amount of data and thousands of published papers referring to the earthquake, many key questions remain. These include: is the Hikurangi subduction interface capable of producing great earthquakes beneath the northeastern South Island? Why did the Hope Fault not accommodate significant slip in the earthquake? Has the earthquake changed the seismic hazard in central Aotearoa New Zealand? Addressing these questions will improve understanding of seismic processes and hazards helping to build resilience to future earthquakes. [ABSTRACT FROM AUTHOR]

The north-striking sinistral reverse Papatea Fault ruptured with a very large (up to 12 m) oblique slip as part of the 2016 MW 7.8 Kaikōura earthquake in the northeastern South Island. Paleoseismic studies were undertaken at three sites along the Papatea Fault, named Murray's roadcut, Jacqui's Gully (both on the main strand), and Wharekiri trench (western strand). These sites provide evidence for up to three Late Holocene paleoearthquakes prior to 2016 (=E0) on this previously unmapped active fault, with preferred OxCal-modelled timings of 98–149 (E1), 546–645 cal yr BP (E2), and >738 cal yr BP (E3). Event correlations between the sites are generally consistent across these past events, implying that the two strands of the Papatea Fault link at depth and rupture together co-seismically as in 2016. Comparisons of its paleoseismic record with the Kekerengu Fault and uplift data from Waipapa Bay and Kaikōura, suggest that the Papatea Fault may have three distinct rupture modes: (i) Kaikōura-type multi-fault ruptures with multi-metre, anelastic block displacements and associated major landscape change; (ii) multi-fault earthquake ruptures with other regional fault combinations; and (iii) single-fault Papatea ruptures with metre-scale displacement. OxCal models offer the possibility that the E1 fault rupture occurred in 1855 CE. [ABSTRACT FROM AUTHOR]

The Mw 7.8 Kaikōura earthquake of November 14th, 2016 provided rare opportunities to evaluate ground deformation during a large strike-slip earthquake. Following the earthquake, both halves of a displaced paleoseismic trench were re-excavated and extended to test, refine, and extend the known late Holocene chronology of surface rupturing earthquakes on the Kekerengu Fault. 28 organic-bearing samples were collected during these excavations. Of these, six samples provided new 14C ages that could be superimposed on the preferred age model of (Little VDR, Kearse J, Norton K, Benson A, Wang N. 2018. Kekerengu fault, New Zealand: Timing and size of Late Holocene surface ruptures. Bulletin of the Seismological Society of America. 108(3B):1556–1572) to derive an expanded, updated age model of earthquake events on the fault that is now based on 16 dated samples. Including the 2016 earthquake, we recognise six surface rupturing earthquakes on the Kekerengu Fault since ∼2000 cal. B.P. Based on the last five events, our analysis yields an updated estimate of the mean recurrence interval for surface rupturing on the fault of 375 ± 32 yrs (1σ) since ∼1650 cal. B.P. An older, sixth event (E5) was not included in the preferred age model due to uncertainties in interpretation; however, incorporating this event into an alternative, six-event age model would adjust the recurrence interval estimate to 433 ± 22 yrs (1σ) since ∼2000 cal. B.P. [ABSTRACT FROM AUTHOR]

During the Kaikōura earthquake, a paleoseismic trench was dextrally displaced ∼9 m and shortened by 1.3 ± 0.4 m – the largest globally recorded displacement of a trench. Analysis showed that two processes accommodated subequal amounts of slip at the surface: (1) discrete dextral-slip on two steeply-dipping faults bounding a <3.5 m wide central deformation zone; and (2) coseismic clockwise rotation of turf rafts and pervasive sediment deformation in that zone. The second (successive) process resulted in upward (<1 m) and outward (<2 m) bulging along low-angle thrusts, creating horizontal fault-perpendicular shortening that exceeds the heave (∼1.3 m). This discrepancy results from coseismic rotation of rafts, that shorten upon approaching perpendicularity with the fault – creating extra apparent shortening (in fault-orthogonal view). Comparison of pre- and post-earthquake trench logs indicates that strike-slip ruptures at the same site can be expressed differently over time; fault strands carrying major displacement in 2016 were not the locus of deformation in the previous earthquake(s), suggesting temporal unpredictability is important in defining fault zones. The last several paleoearthquakes at the trench produced cm-dm scale normal-sense dip separations across faults; however, the 2016 earthquake created compressive structures including up-bulging and low-angle reverse faulting, as well as fissuring. This contrast in deformation style likely resulted from an >8° clockwise rotation of the local slip vector in 2016 (becoming transpressive), highlighting that small changes in slip kinematics may affect rupture zone structures. [ABSTRACT FROM AUTHOR]

The Geological Survey of Israel (GSI) was founded in 1948 with the establishment of the State of Israel. Over the years, changes of the research directions were dictated by national needs as the population grew from less than 1 million to more than 9 million in 2020 in a small country of only 22,000 km2 with highly diverse geological features. This was associated with a change in the structure of the survey and establishing it as a key player in sustainable development and effective utilization of natural resources. It became possible by the upgrade of the staff levels and the research facilities after the survey was recognized as an independent research institute by the government. The achievement of the GSI as an applied science organization in response to the country's ever-developing challenges is going hand in hand with becoming an international geo-scientific recognized organization. [ABSTRACT FROM AUTHOR]

We investigate the correlation between precipitation, clouds and cosmic rays based on field observations to develop a new short-term forecasting tool for their extremely high values. The results show that the cosmic ray intensity appears to be highly correlated with the one-year time-lagged rainfall amount with the cosmic rays leading. A plausible explanation is given for this, based on the modulation of cosmic rays by the solar cycle and an earlier finding of a strong correlation between the stratospheric - lower mesospheric temperature fluctuations and the sunspot number cycle with a time lag of one year (sun leading). This suggests that cosmic rays are not the trigger, but rather signals sunspot activity that with a delay of one year may affect cloud formation and therefore rainfall. In addition, high rates of rainfall exhibit a power-law behavior, such as the Gutenberg-Richter law characterizing the large area and perimeter size of rainfall and clouds, which have been proposed recently. Finally, the new tool for the nowcasting the extremely high cosmic ray intensity values can be used for nowcasting the extremely high rainfall values. Their combination can be used to study the modulation of cosmic ray properties by climate change parameters. [ABSTRACT FROM AUTHOR]

Seismic vulnerability of speleothems may serve long-term seismic risk studies. For this reason, the seismic response of stalagmite is computed using a robust FEM model calibrated from free vibration records by Hilbert–Huang modal extraction. It is demonstrated that the stalagmite vibrations consist of pairs of closely coupled flexural natural modes with a negligible role of vertical excitations. The location of the breaking point of the stalagmite is a result of a balance between the overturning bending moment and variations of horizontal cross-sections with height. Safety margins are investigated, and the ultimate peak velocity of excitations equaling 3.4 mm/s is estimated. [ABSTRACT FROM AUTHOR]

Karst cave is a sort of special and buried geological structure that was widely developed in the Permo-Carboniferous coal accumulation area of North China. It brings karst collapse and safety hazard in the mining industry. In this study, we propose a seismic structure-constrained inversion of controlled source audio-frequency magnetotelluric (CSAMT) data on a detailed survey and detection of karst caves. Instead of constrained by seismic impedance, the method in this study directly takes the seismic imaging results as structural constraints, which is different from the cross-gradient technique used by conventional structural constraints. First, the seismic migration section is divided according to the CSAMT inversion grid and applied pixel extraction for each grid. Clustering is carried out according to the structural information interpreted by the seismic migration section and the average pixel value of each cluster is calculated. Then the clustered results were used in the seismic structure-constrained inversion of CSAMT data based on cross-gradient technique. After that, as a karst cave model developed in limestone was established, the study compares the structure-constrained inversions with different clustering strategies shows a much more precision of karst cave detection than the method only applies CSAMT data. Moreover, experimental verification is provided in this study, which is for the detection of a suspected karst collapse column from Shandong Province, China. The comparison results further show that the structure-constrained inversion method proposed in this paper is applicable and may effectively improve the locating accuracy of karst caves. [ABSTRACT FROM AUTHOR]

We present the first paleoseismic investigation of the Hyde Fault, one of a series of north-east striking reverse faults within the Otago range and basin province in southern New Zealand. Surface traces of the fault and associated geomorphology were mapped using a lidar digital elevation model and field investigations. Trenches were excavated at two sites across fault scarps on alluvial fan surfaces. The trenches revealed stratigraphic evidence for four surface-rupturing earthquakes. Optically stimulated luminescence dating constrains the timing of these events to around 47.2 ka (37.5–56.7 ka at 95% confidence), 34.6 ka (24.7–46.4 ka), 23.5 ka (19.7–27.3 ka) and 10.5 ka (7.9–13.1 ka). We obtain a mean inter-event time of 12.4 kyr (2.3–23.9 kyr at 95% confidence) and the slip rate is estimated to be 0.22 mm/yr (0.15–0.3 mm/yr). We do not find evidence to suggest that earthquake recurrence on the Hyde Fault is episodic, in contrast to other well-studied faults within Otago, suggesting diverse recurrence styles may co-exist in the same fault system. This poses challenges for characterising the seismic hazard potential of faults in the region, particularly when paleoearthquake records are limited to the most recent few events. [ABSTRACT FROM AUTHOR]

Gunung Merapi (Mountain of Fire) is the guardian of a cosmogonic-sacred landscape, and one of the most dangerous volcanoes in the world. Its eruptions are well studied, however, the relationships among ritual, science, protection and grassroots disaster management arising after the 2006 and 2010 eruptions are mostly overlooked. This paper fills this gap in the literature, through qualitative research that explores local perceptions and places respiratory protection in a larger ecology of protective practices during, and after, volcanic crises. In a previous study, 99% of respondents in Yogyakarta used masks to protect from inhaling volcanic ash. In order to understand the respiratory protective practices developed, in the last decade, to cope with Merapi's eruptions, we need to engage with the emergence of the local volunteer-led grassroots monitoring systems. Although these networks were formalised by agencies, they were originally set-up in a bottom-up fashion to respond to pyroclastic flows and other life-threatening volcanic hazards. Our research found that they play a key role in the distribution of masks and respiratory health narratives, thus influencing the wide adoption of certain types of respiratory protection. Disaster management agencies, village heads, ritual experts and volunteers participating in these monitoring networks share spiritual signals (dreams) and scientific ones (seismic data, health narratives) and masks as part of their response to volcanic crises. Our findings about these Merapi networks challenge dominant assumptions in the Disaster Risk Reduction literature that tend to equate building resilience with the substitution of problematic 'cultural beliefs' for 'scientific facts'. [ABSTRACT FROM AUTHOR]

This paper presents an application of the Conditional Mean Spectrum (CMS) methodology for sourcing accelerogram records for use in dynamic analyses of structures in intraplate regions of lower seismicity. The main challenges with deriving CMS for selecting and scaling accelerograms in regions of lower seismicity stem from the paucity of representative strong motion data and event recurrence data. A step-by-step illustration of the methodology is presented using the south-eastern Australia (SEA) region as an example. The study involves making use of a diversity of Ground Motion Prediction Expressions (GMPEs) including a recently developed regionally adjustable Component Attenuation Model (CAM). Three different schemes using a weighted averaging of candidate GMPEs were adopted and a comparison of predictions demonstrated only minor differences confirming the robustness of the modelling. The CMS constructed in this study have been used to develop a proposed suite of scaled accelerograms for SEA. [ABSTRACT FROM AUTHOR]

For the high-precision seismic imaging of complex structures on irregular topographies, this study proposes a Chebyshev spectral-element reverse time migration (CSE-RTM) method coupled with the implicit Newmark time integral method. The approach is first applied to a numerical example to consider factors affecting numerical accuracy, such as the time step and the pattern of subdivision of the computational domain. The results show that the smaller the time step is, the higher the numerical accuracy is and that numerical accuracy improves when the grid nodes tend to be distributed uniformly in the computational domain. The spectral element method combines the advantages of the stronger boundary-related adaptability of the finite element method with the high accuracy and fast convergence of the spectral method. This method is applied to reverse time migration imaging, and tests of the model show that its accuracy of imaging is higher than that of the conventional finite-difference reverse time migration method in case of complex structures in areas with irregular topography. To improve the efficiency of parallel computing of the CSE-RTM, an iterative algorithm is proposed to solve the hierarchical equilibrium sparse linear equations (HELPs) for it based on the idea of the degrees of cohesion of freedom and local relaxation. This algorithm has the advantage that the efficiency of parallel computation does not decrease with an increasing number of processors while the number of iterations required for convergence is controlled. Owing to the fast convergence of the spectral method on a sparse grid coupled with the parallel computational scheme of HELPs, the efficiency of calculation of the CSE-RTM is significantly improved. [ABSTRACT FROM AUTHOR]

For much of Russia's fractious history, the earth's stability at least could be taken for granted. The imperial heartland was situated deep on the Eurasian tectonic plate, rarely experiencing fatal seismic activity. As the empire expanded, however, it acquired several of Eurasia's most earthquake-prone regions. This interplay between colonization and seismic landscapes produced a novel entity: the 'seismic colony'. With its occasional earthquakes and perpetual risks, the seismic colony posed a significant challenge to Russian rule, particularly in Turkestan. Earthquakes devastated infrastructure, gave lie to the civilizing mission and fostered social disorder, thereby undercutting the technologies of rule that the empire relied on to exploit the region. Engaging analytical tools from the history of environment and technology, this article details this threat and the developments it prompted from Russian experts and settlers, including first-response efforts, reconfigured construction practices, and the concretization of seismology as a science and infrastructure. [ABSTRACT FROM AUTHOR]

To explore crustal structures using seismic records of earthquakes, we proposed a new seismic reflection imaging method based on reverse time migration (RTM) without source information. In the proposed RTM method using multiple reflections between surface and subsurface boundaries, we correlate forward- and backward-extrapolated wavefields of the same observation records from all receivers at once. We implemented acoustic RTM based on a scalar wave equation and elastic RTM based on a velocity-stress formulation for wavefield modelling. Furthermore, we adopted scalar and vector potential formulations in elastic RTM to obtain separate P- and S-wave reflection images. In our study, numerical simulations with a regional crustal structure model were conducted to compare combinations among the synthetic data by acoustic or elastic wave modelling, observation conditions, and RTM formulations. We demonstrated the validity of the proposed method with idealised dense observations and confirmed a limitation due to quasi-realistic sparse observations. Artefacts due to the mixture of P- and S-waves in the acoustic RTM images from elastic synthetic data were attenuated by elastic RTM, which addresses the proper illumination of P- and S-wave reflections. [ABSTRACT FROM AUTHOR]

Brittle punching failures can occur in slab–column connections due to earthquake-induced unbalanced moments. The performance of undamaged specimens and various repair/strengthening techniques have been studied in the past. This paper investigates a less studied scenario, in which a flat slab–column connection severely damaged by an earthquake is subjected to another earthquake without undergoing repair. The performance under this special loading protocol is analysed. It is shown that the drift capacity was not significantly impaired, but both the lateral and bending stiffness were reduced. Other relevant observations regarding the post-earthquake life of slab–column connections are brought to attention. [ABSTRACT FROM AUTHOR]

Reduced 1/20 and 1/40 models of the Baalbek columns were subjected to harmonic excitations of varying amplitudes and periods to investigate rocking and overturning. 2D UDEC numerical simulations and a simple critical impulse theoretical model showed good agreement with the experimental results. The similitude established between models and full-size columns can be used to predict the response of full-sized columns to earthquakes through experimental simulation and numerical modeling. The observed mode of overturning and number of blocks overturned could be used to estimate the period and peak acceleration of the critical impulses contained in earthquake signals. [ABSTRACT FROM AUTHOR]

The glacio-fluvial sediments of the Whataroa Valley on the west coast of New Zealand's South Island contain a record of environmental change since the Last Glacial Maximum. The valley is cut by the Australia–Pacific plate-bounding Alpine Fault, the position of which is obscured by recent glacio-fluvial outwash deposits. Five seismic profiles collected across the inferred surface trace of the Alpine Fault between 2011 and 2018, using a variety of source types, are presented here; these profiles provide constraints on the fault's location in the upper few hundred metres of the near surface. The sedimentary strata in the Whataroa Valley have been classified into seismic facies based on their reflectivity characteristics. Two reflective seismic facies, recognisable in all profiles, have been interpreted to correspond to recent fluvial outwash gravels (seismic facies 1) and older post-glacial glaciofluvial or marine sediments (seismic facies 2). These reflective packages are cut by Alpine Fault rupture surfaces with reverse motion dips of 60° to 80° and total throw of up to 50 m. Faults imaged in three of the profiles are interpreted to correspond to the most recent surface rupture of the Alpine Fault, due to their close proximity to a recently trenched surface scarp. [ABSTRACT FROM AUTHOR]

Part of North-Western Himalaya particularly Uttarakhand has been identified by several eminent seismologists as gap area where large size earthquake (greater than magnitude 7) is expected. The region has witnessed two earthquakes having a magnitude greater than 6 in last 25 years (March 28, 1999 Chamoli earthquake and October 20, 1991 Uttarkashi earthquake) both having an epicenter in Gharwal region of Uttarakhand. Several studies have shown that a future large earthquake in central Himalayas can generate severe ground motion in the National capital region of Delhi, which is about 300 km from this expected source. Several densely populated cities and villages having total population of several millions are located between Delhi and Uttarakhand. These towns/cities will be severely affected by a large earthquake having an epicenter in this region. Using advancements in communication technology and real-time seismology, a project to have an earthquake early warning system for Northern India is under progress at Indian Institute of Technology, Roorkee. In this project, a dense network of 84 accelerometers has been installed covering an area of about 100 × 40 km in Garhwal region. This network has an average station to station distance of less than 10 km and all the sensors are streaming data, which is being processed in real time at central server stationed at Roorkee. This paper describes details of the network, sensors, present status of development, performance of instrumentation during recent events, and processing details. [ABSTRACT FROM AUTHOR]

The damages done by earthquakes in the human history can't be denied in any sense as the phenomenon is responsible for bringing catastrophes both socially and economically. It is known that Pakistan is located in one of the seismically active regions of the world. The Quetta earthquake which occurred in 1935, the Ziarat earthquake of 2008, the Kashmir earthquake in 2005 and the Dallbaandin earthquake in 2011 bear the testimony of active seismicity in Pakistan. The Building code of Pakistan (BCP) 2007 has placed Peshawar in seismic zone 2B with a PGA range of 0.16–0.24. However, this is not in line with the historical data and available ground motion records. Therefore, in this research, a probabilistic seismic hazard assessment technique was used to estimate the strong ground motion parameters for a grid of 11 km by 11 km, covering all the active faults within and around the Peshawar region and having significant effect on the seismicity of Peshawar. Moreover, PGA along with spectral acceleration values are required by modern building codes (IBC 2009 and ASCE-7) for the estimation of seismic loads, is calculated. From seismic hazard analysis, it was found that Peshawar lies in seismic Zone 1 with a PGA value of 0.06. The estimated PGA value was also validated and in line with the PGA values obtained from the ground motion records of Peshawar Meteorological Department. [ABSTRACT FROM AUTHOR]

The transition between the North Australian Craton and the Thomson Orogen in the area south of the Mount Isa terrane lies under cover and is a critical element in interpretation of the nature of the Tasmanides. The location of the boundary between these domains is controlled by potential field results; the gravity and magnetic signatures are most sensitive to shallow structure, and so there is little information on structure at depth. Full-crustal reflection profiling crosses the boundary in a few locations but does not provide areal coverage. A deployment of 79 passive seismic stations spanning from southern Queensland into the Mount Isa terrane (AQT experiment) is exploited to examine the variations in crustal thickness and the nature of crustal structure across an area with no prior sampling. The analysis exploits the autocorrelation of the seismic signals that extracts the reflection response from the transmitted signals recorded at the surface, which can be migrated to provide an image of structure at depth. The combination of the active and passive seismic results and other geophysical data indicates that the structure of the northern and central Thomson Orogen is relatively homogeneous with a highly reflective, and magnetic, lower crust suggesting a common substrate across the region. The crust thickens and changes character in the North Australian Craton with variations under cover that can be linked to the areas of exposure. There is a zone approximately 100 km wide that separates the characteristic seismic signatures of the two domains indicating reworking at the craton margin. A combination of passive and active seismic imaging sheds light on the transition from the Thomson Orogen to the North Australian Craton. The north central Thomson Orogen shows a consistent reflection character with a strong band of lower crustal reflectivity. The North Australian Craton shows seismic domains with varying character of reflectivity and crustal thickness. A transition zone about 100 km wide separates the distinctive styles of crustal architecture. [ABSTRACT FROM AUTHOR]

A strident focus on atmospheric carbons and on climate change as its distinguishing feature has seen much debate and research surrounding the Anthropocene stray from its conceptual grounding in geology. Yet new research argues that hallmarks of the Anthropocene such as sea-level rise, melting ice sheets, and environmental engineering projects designed to mitigate chronic shortages of potable water all increase the potential of seismic activity, placing geological forces back at the center of conversations on planetary futures. Following calls to consider the political dimensions of environmental change in the Anthropocene, this article examines the multiple layerings of natural hazards, political crises and transformations, and mega-urbanization through the lens of catastrophic geological events, drawing evidence from an ongoing longitudinal study of the devastating Mexico City earthquakes of 1985 and 2017. This case suggests that such events intersect with contemporary political economy in a variety of ways, from the disruption of urban investment patterns and the initiation of processes of mass abandonment or of creative destruction and gentrification to the exacerbation of political crises at scales from the submunicipal to the supranational, the facilitation of social movement formation, and the acceleration of political revolutions such as Mexico's democratic transition of 2000. These insights offer productive avenues for engaging with the political economies of geological events and processes and the prescriptive powers of geology as a field of knowledge production and political power that increasingly demand attention across an urbanizing planet. [ABSTRACT FROM AUTHOR]

Paleoseismic offsets are important parameters for evaluating fault activity. With the development and popularization of unmanned aerial vehicles (UAVs) and structure-from-motion (SfM) photogrammetry, more and more low-cost mini-UAVs have been used for geoscience studies like active faults and paleoearthquakes. In this study, we take the Gebi ridge in the middle of the Altyn Tagh fault (ATF) in western China as an example of using the control-free images acquired by a mini-UAV and SfM to measure paleoseismic offsets. The measurement accuracies of the control-free images acquired by a mini-UAV were evaluated, and then the horizontal offsets of the land surface caused by paleoearthquakes were measured. After comparing the total number and anomalies of paleoearthquake events identified by UAV-based photos with those revealed by geological trenches nearby, the following conclusions can be drawn. (1) Although the absolute positioning accuracy of the control-free image from the mini-UAV and SfM is poor, the accuracy of relative horizontal measurement is acceptable. (2) Without the help of ground control points (GCPs), the accuracy of relative vertical measurement for aerial images is not sufficient to measure vertical offset. (3) Oblique photography can improve not only the accuracy of paleoseismic landform mapping but also flight safety. (4) Up to 11 paleoearthquakes have been identified through paleoseismic offset measurements using control-free images in the study area. And both the total number and the anomalies of paleoearthquakes are consistent with the geological evidence in nearby geological trenches. By taking into account the above factors, it can be concluded that it is feasible to measure the horizontal offset of the land surface caused by paleoearthquakes using control-free images from mini-UAVs and SfM. [ABSTRACT FROM AUTHOR]

Due to high imaging precision and adaptability for steep-dip interfaces, reverse time migration (RTM) has become the preferred choice in seismic imaging. However, low-frequency noise is a common problem in RTM and effects the clarity of the final image. The noise is formed by the cross-correlation of source and receiver wavefields that propagate along the same paths. A wavefield decomposition imaging condition (WDIC) can eliminate this low-frequency noise by separating the wavefield into up–down or left–right directions and then cross-correlating source and receiver wavefields along the different propagation paths. Nevertheless, many backscattered waves propagating along horizontal, nearly horizontal, vertical and nearly vertical directions exist in vertical seismic profile (VSP) data. These waves are difficult to separate and generate the residual low-frequency noise when applying WDIC to VSP RTM. To overcome this, Poynting vector filtering is combined with WDIC to attenuate the noise. Several numerical case studies testify to the effectiveness of the analysis and method. [ABSTRACT FROM AUTHOR]

The finite difference method is widely used in seismic wave numerical simulation, reverse time migration and full waveform inversion. However, the numerical dispersion problem seriously affects the results of seismic imaging and inversion. Based on this, we introduced cosine-combined window function (CCWF) used in harmonic analysis of the power system and compared the amplitude response and error properties with other window functions. Then, an optimised CCWF and a new weighting method are proposed, which results in finite-difference operators with not only large spectral coverage but also small precision error fluctuation. In this paper, the analysis shows the good stability of using finite difference operators. Finally, we perform numerical forward modelling, which denotes that our method is superior than other optimum methods. From an economic point of view, this method will effectively reduce the computation cost and improve efficiency. [ABSTRACT FROM AUTHOR]

We study integral transforms mapping a function on the Euclidean plane to the family of its integration on plane curves, that is, a function of plane curves. The plane curves we consider in the present paper are given by the graphs of functions with a fixed axis of the independent variable and are imposed some symmetry with respect to the axes. These transforms contain the parabolic Radon transform and the hyperbolic Radon transform arising from seismology. We prove the inversion formulas for these transforms under some vanishing and symmetry conditions of functions. [ABSTRACT FROM AUTHOR]

The objective of this study is to quantify the seasonal and multi-annual variability and trends of low-flow river conditions in southeastern Poland. The study was performed using daily values of river discharge at 29 gauging stations for hydrological years 1976–2014. The results show regionally specific patterns, such that seasonality is high for the lowland rivers (low flows occur during the warm season), while in the upland rivers a 10- to 15-year cycle is observed. Increasing trends in warm-season temperature and a decrease in humidity were observed; however, no direct correlation with low flows was found. These results suggest that the initiation and maintenance of low-flow events over some regions are more sensitive to local surface water and groundwater circulation conditions than to atmospheric drivers, especially when the recurrence interval of events is low, and that the primary mechanisms driving and maintaining low-flow conditions can change over relatively small spatial scales. [ABSTRACT FROM AUTHOR]

We consider the decentralised consensus optimisation problem arising from in-situ seismic tomography in large-scale sensor networks. Unlike traditional seismic imaging performed in a centralised location, each node in this setting privately holds an objective function and partial data. The goal of each node is to obtain the optimal solution of the whole seismic image, while communicating only with its immediate neighbours. We present a fast decentralised gradient descent method and prove that this novel method can reach optimal convergence rate of O (1 / k 2) where k is the number of communication/iteration rounds. A gossip-based asynchronous version is also proposed which is preferable when there is a divergence on the processing speed of the nodes. Extensive numerical experiments on synthetic and real-world sensor network seismic data demonstrate that the proposed algorithms significantly outperform existing methods. [ABSTRACT FROM AUTHOR]

In seismic exploration, the dominant applications are still based on the acoustic wave assumption because of the simplicity and computational efficiency. Compared to the acoustic wave equation, the elastic wave simulation is more accurate, especially for land data, to characterise the elastic property of the real earth, but it is also far more expensive in terms of the computational cost. The traditional way to solve the first order velocity-stress elastic wave equation is based on a second order staggered grid time domain finite difference stencil, and this stencil is expensive because the time step is usually very small due to the limitation the stability condition and numerical dispersion relations. When the fourth order Lax-Wendroff stencil is applied, the time step could be larger but the computational cost triples that of the second order stencil for each time step. To improve the efficiency of the Lax-Wendroff stencil, we rewrite the first order velocity-stress equations into a combination of second order and zeroth order temporal derivative equations. When the second order stencil is applied to the new equation, there is no benefit compared to the original equation; when the fourth order Lax-Wendroff stencil is applied, the computational cost only doubles for each time step, which is 33% faster than the Lax-Wendroff stencil applied on the original equation. Both memory consumption and computational cost are compared among the four different numerical stencils, and a staggered grid Pseudo Spectral method is applied to prevent the numerical dispersion for computing the spatial derivatives. Numerical tests are performed on a 2D homogeneous media and a 2D line of the SEAM II Arid model. The results suggest that although the memory cost is increased, the Lax-Wendroff stencil applied to the second order temporal derivative equations is the optimal option in terms of the both accuracy and computational cost. [ABSTRACT FROM AUTHOR]

The staggered grid finite difference (SGFD) method has been widely utilised in seismic forward modelling. The accuracy of forward modelling results has a great influence on the results of subsequent seismic imaging and seismic inversion. Numerical dispersion is one of the inherent problems in the SGFD method. To suppress dispersion, we here introduce the truncated window function method, which can get optimised finite difference operators after truncating spatial convolution series of the pseudo-spectral method. The empirical criteria of window functions are the main lobe width that should be as narrow as possible and the side lobe attenuation should be as large as possible. According to these criteria, we propose the combined window function method based on the Gaussian window and Hanning window. The result of the amplitude spectrum response shows that the new combined window has narrower main lobe and greater side lobe attenuation, which results in higher accuracy in numerical simulations with SGFD operators. Numerical tests also illustrate the effectiveness of this new method. [ABSTRACT FROM AUTHOR]

We present the results of a paleoseismic study of the Akatore Fault in the low seismicity region of Otago, New Zealand. Two trenches reveal at least three reverse fault ruptures that are constrained to have occurred between 13,314 B.C. and 680 A.D. (antepenultimate event), 737 and 960 A.D. (penultimate event) and 1047 and 1278 A.D. (most recent event), with a single-event displacements of 1.6–2.5 m. Ground Penetrating Radar (GPR) profiles and sediment analyses show that a 125 ka marine terrace is likely also only displaced by these three events, suggesting these earthquakes have ended a minimum 110,000 year period of quiescence on the fault. The fault therefore appears to exhibit strong aperiodicity of earthquake occurrence, a characteristic previously suggested for the Akatore Fault and other well-studied Otago faults. Slip rate and recurrence interval for the current active period are 0.3–6.0 mm/yr and 450–5110 years respectively. We suggest that for seismic hazard assessments in nearby Dunedin it is prudent to assume that the high rates of recent earthquakes will continue into the immediate future on the Akatore Fault. [ABSTRACT FROM AUTHOR]

We quantify flexural deformation of subducting oceanic plates at a global array of 15 ocean trenches, using a new approach of modelling spatial variations in flexural bending shape and curvature. The investigated trenches are chosen to represent a diverse range of subducting plate age of 24–150 Ma, including the Middle America, Peru, Chile, West and East Aleutian, Sumatra, North and South Philippine, Tonga, Kermadec, Kuril, Japan, Izu-Bonin, and South and North Mariana. The studied trenches show systematic intra- and inter-trench variability in the calculated flexural bending curvature, stress distribution, extensional brittle yield zone, and effective elastic plate thickness Te of the subducting plates. We find that subducting plate age is a critical factor controlling the bending curvature and the corresponding extensional yield zone. The width, depth, and area of the extensional yield zone are all calculated to increase systematically with the subducting plate age. The newly-developed curvature analysis can yield continuously varying apparent Te(x) from the trench axis to outer rise. The calculated extensional yield zones from the curvature analysis are in general consistent with the observed normal faulting earthquakes of magnitude≥6.0 at the 15 global trenches. Our analyses also reveal that the five deepest regions of the global trenches, i.e. the Challenger, Horizon, Serena, and Scholl Deeps and Galathea Depth, are associated with relatively large flexural bending and calculated yield zones comparing to their respective adjacent trench segments. The Serena and Challenger Deeps of the S. Mariana trench are calculated to have the largest flexural bending among the five deeps. [ABSTRACT FROM AUTHOR]

The 14th November 2016 Kaikōura earthquake was one of the most complex crustal earthquakes recorded in the modern era. The rupture propagated northward for more than 170 km along both mapped and unmapped faults causing widespread damage across central New Zealand. Field, Satellite Radar and GPS observations revealed ground displacements of up to 6 m (fault offsets of ∼12 m), extensive coastal uplift and large scale anelastic deformation including the ∼10 m uplift of a fault-bounded block.In the aftermath of the earthquake, slip models have estimated as much as 25 m of slip at depth along with the potential co-seismic rupture of the southern Hikurangi subduction interface. From the complex network of faults, exhibiting a variety of slip kinematics, to the large co-seismic slip, this earthquake has challenged our assumptions about fault segmentation in multi fault ruptures with important implications for seismic hazard. Following the earthquake, studies from multiple national and international groups have started to unravel some of the earthquakes complexities. Here I will present a broad overview of the current findings and discuss some of the ongoing debates and questions which have yet to be resolved. [ABSTRACT FROM AUTHOR]

In the nineteenth century, Ernst Chladni's acoustic figures provided productive new experimental techniques for investigating natural phenomena. The movement of invisible forces, such as light, electricity, magnetism, and heat, were hard for natural philosophers to examine. But Chladni's use of vibrating glass plates and sand to reveal the wave motions of sound offered an experimental framework through which to make natural phenomena visible. In Britain, it was Michael Faraday and Charles Wheatstone in the 1820s and 1830s who made best use of these practices and apparatus. Sound waves also provided new ways of thinking about earthquakes and seismic phenomena. This article explores how Robert Mallet, the first self-styled "seismologist", examined earthquakes, drawing on broader philosophical work surrounding vibrations and acoustic waves. Mallet was keen to draw parallels between the movement of seismic shock waves and the movement of musical sounds, including those from a piano moving through a room. He was not alone in this respect. Charles Darwin, among others, noticed comparisons between the sonorous and the seismic. By contextualising Victorian seismology within the context of Victorian acoustic science, this article argues that the two disciplines were deeply connected. [ABSTRACT FROM AUTHOR]