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We have kindly received the comments by Hamdache and Pelàez on our published paper (Hamidatou et al. 2019); This article will give us the opportunity to provide more explanation and clarifications on the methodology followed during our work. We find these comments and critiques helpful for our future works. However, most of them were generated from the misapprehension of the paper by the comment authors. These remarks were mainly based on (1) the misjudging of the seismic source zone model used in relation to the active faults in the study area, (2) suspecting that the probabilistic seismic hazard PGA values were wrongly quoted from their analyses in our work, and (3) the logic tree usage , for which we here provide further general clarifications. [ABSTRACT FROM AUTHOR]

We would like to make some comments on the paper by Hamidatou et al. (2019). Initially, these comments are motivated to reveal that, previous results on probabilistic seismic hazard analyses, some of them computed and published by our research group, are wrongly quoted in the paper by these authors. In our opinion, some other points are worthy of debate, mainly, but not only, the used seismic source zone model, the used logic-tree, and also the comparison of estimated values of peak ground horizontal acceleration (PGA) with previous results. [ABSTRACT FROM AUTHOR]

Fifteen papers are included in this PAGEOPH topical issue "Sixty Years of Modern Tsunami Science, Volume 2: Challenges." The issue starts with a general introduction, and then briefly summarizes all contributions, first papers addressing general topics, and then articles grouped on a regional basis: Northern Pacific, Southeast Pacific, Southwest Pacific and Indonesia, and Mediterranean regions. [ABSTRACT FROM AUTHOR]

Twenty-three papers are included in this PAGEOPH topical issue "Sixty Years of Modern Tsunami Science, Volume I: Lessons and Progress". The papers are grouped into four categories: historical tsunami events, studies on tsunami source models and case studies, tsunami hydrodynamics, and probabilistic tsunami hazard assessment and forecasting. Papers that reflect the current state of tsunami science and research are briefly introduced. [ABSTRACT FROM AUTHOR]

Tsunamis generated by volcanic eruptions have risen to prominence since the December 2018 tsunami generated by the flank collapse of Anak Krakatau during a moderate eruption and then the global tsunami generated by the explosive eruption of the Hunga volcano in the Tongan Archipelago in January 2022. Both events cause fatalities and highlight the lack in tsunami warning systems to detect and warn for tsunamis induced by volcanic mechanisms. Following the Hunga Tonga—Hunga Ha'apai eruption and tsunami, an ad hoc working group on Tsunamis Generated by Volcanoes was formed by the Intergovernmental Oceanographic Commission of UNESCO. Volcanic tsunamis differ from seismic tsunamis in that there are a wide range of source mechanisms that can generate the tsunamis waves and this makes understanding, modelling and monitoring volcanic tsunamis much more difficult than seismic tsunamis. This paper provides a review of both the mechanisms behind volcanic tsunamis and the variety of modelling techniques that can be used to simulate their effects for tsunami hazard assessment and forecasting. It gives an example of a volcanic tsunami risk assessment undertaken for Stromboli, outlines the requirement of volcanic monitoring to warn for tsunami hazard and provides examples of volcanic tsunami warning systems in Italy, the Hawaiian Island (USA), Tonga and Indonesia. The paper finishes by highlighting the need for implementing monitoring and warning systems for volcanic tsunamis for locations with submarine volcanoes or near-shore volcanoes which could potentially generate tsunamis. [ABSTRACT FROM AUTHOR]

To catalyze transformative advancements in High-energy Physics in the Atmosphere (HEPA), a comprehensive understanding of particle fluxes, electric fields, and lightning occurrences across atmospheric layers is imperative. This paper elucidates the instrumentation and capabilities of the Aragats Space-Environmental Center (ASEC), which encompasses measurement tools for various cosmic ray species, near-surface electric fields, and lightning events integrated across high-mountain research station at slopes of Mt. Aragats and the highest mountains of Eastern Europe and Germany. Through these measurements, we aim to elucidate models of particle acceleration mechanisms and the charge distribution within the lower atmosphere. We introduce an Advanced Data Extraction Infrastructure (ADEI) integrated with sophisticated statistical analysis tools to facilitate rapid access to this wealth of data. Despite the significance of these atmospheric processes, the intricate interplay between thundercloud electrification, lightning activity, wideband radio emissions, and particle fluxes remains poorly understood. A particularly compelling avenue of inquiry lies in exploring the relationship between high-energy atmospheric phenomena, intracloud electric fields, and lightning initiation. Furthermore, investigations into accelerated structures within geospace plasmas hold promise for shedding light on particle acceleration processes, potentially extending to higher energies within analogous structures in cosmic plasmas. This paper also examines practical methodologies for extracting meaningful physical insights from temporal datasets, such as correlating surges in particle flux intensity with variations in near-surface electric field strength and precipitation patterns. Additionally, we explore the utility of wideband field and interferometer antenna signals in this context, offering valuable avenues for further research and analysis. Through these endeavors, we aim to deepen our understanding of high-energy atmospheric processes and their broader implications for terrestrial and cosmic phenomena. [ABSTRACT FROM AUTHOR]

Pure and Applied Geophysics (PAGEOPH) is one of the leading journals in the field of geophysics. The first issue was published in 1939; thus, the journal is celebrating its 80th anniversary in 2018. The aim of this paper is to provide a complete lifetime overview of the academic structure of the journal using bibliometric indicators. This analysis includes key factors such as the most cited articles, leading authors, originating institutions and countries, publication and citation structures, and the most commonly used keywords. The bibliometric data used to conduct this analysis comes from the Scopus database. Additionally, the visualization of similarities (VOS)viewer software is used to create a graphic map of some of the bibliometric results. The graphical analysis uses co-citation, bibliographic coupling and co-occurrence of keywords. The results indicate that PAGEOPH is a leading journal in the areas in which it is indexed, with publications from a wide range of authors, institutions, and countries around the world. [ABSTRACT FROM AUTHOR]

In a recent paper, Verma and Srivastava [1] discussed the vibrations of an inhomogeneous, transradially isotropic, spherical shell. An assumption made by these authors at the very outset appears to be incorrect. Consequently, most of the equations and results obtained by them are either wrong or irrelevant. The purpose of this note is to point out these mistakes and give the corresponding correct results. The notation of Verma and Srivastava is used throughout. [ABSTRACT FROM AUTHOR]

The establishment of a unified earthquake catalog is a basic requirement for attaining a detailed seismological analysis and an improved seismic hazard assessment. Accordingly, the current research paper aims to present a reliable instrumental unified earthquake catalog for the northern part of Algeria. This unified catalog is compiled using regional empirical relationships derived from converting different magnitude scales to an advanced physical-based moment magnitude scale suggested in the recent literature and denoted by Mwg. The regression methodology used in this study is called the New General Orthogonal Regression approach (N.GOR), which was selected since it is the most trustworthy procedure for scaling the magnitudes to Mwg. To highlight the significance of using the N.GOR, the obtained outcomes of the scaling relations were compared with those issued from the conventional general orthogonal regression (GOR) method, which is deemed to be the most dependable methodology used worldwide for magnitude conversion problems. The unified earthquake catalog was assembled from 1954 to 2022. Reliably converting the original magnitudes into homogenized moment magnitude leads to a complete and consistent unified earthquake catalog. Indeed, the unified moment magnitude catalog presented in this paper could provide reliable data for studying earthquakes distribution and the assessment of seismic hazards in the north of Algeria. [ABSTRACT FROM AUTHOR]

This paper focuses on building a ground motion model (GMM) using artificial neural network technique driven by a synthetically generated database in a data poor region. A hybrid simulated method considering nonlinear site response is used to generate potential ground motions in Tianjin area. The synthetic database containing a total of 9267 ground motion records from 93 simulated earthquake events are utilized to develop the model. A back propagation neural network developed by genetic algorithm (GA-BPNN) is used to obtain the optimal weights and biases that most fit the target dataset without overfitting. The structure of GA-BPNN model consists of 322 unknowns including weights and biases that connect input and output parameters. The model is developed to predict PGA and 5% damped spectral acceleration (periods from 0.01 to 10 s). The input parameters consist of moment magnitude (Mw), strike (φ), dip (δ), rake angle (λ), focal depth (h), epicenter distance (R) and azimuth (θ). The model performance is observed to be within the appropriate error limits. It is found that the model has the ability to capture the parametric variation relationship. Additionally, the synthetically based model is compared with empirically based GMM relations derived from NGA-West2, finding it has similar performance and behavior to leading GMMs. The model application in Tianjin area demonstrates that this paper provides a scheme to utilize synthetic database and build GMMs in data poor regions. [ABSTRACT FROM AUTHOR]

Twenty-one papers on the 2011 Tohoku, Japan tsunami are included in Volume I of the PAGEOPH topical issue 'Historical and Recent Catastrophic Tsunamis in the World.' Two papers discuss seismological aspects of the event with an emphasis on tsunami generation and warning. Five papers report the impacts and effects in Japan through field surveys of tsunami heights, building damage, and tsunami deposits or analysis of satellite data. Eight papers report the tsunami effects on other Pacific coasts, including the Kuril Islands, the USA, French Polynesia, the Galapagos Islands, Australia, and New Zealand. Three papers report on analyses of the instrumental records of the 2011 Tohoku tsunami, and two more papers report their modelling efforts of the tsunami. Several of the above papers also compare the 2011 Tohoku and 2010 Chile tsunamis. [ABSTRACT FROM AUTHOR]

Epistemic uncertainty offers alternatives on decision making and various possibilities of computing the hazard integral. Generally, the logic tree approach is used while treating the epistemic uncertainty. Logic tree weight calculation is a subjective decision based on the degree of belief of the analyst on the possible contributors to the epistemic uncertainty and often leads to a different set of values by different researchers. This paper aims to develop a framework of accounting for the epistemic uncertainty in probabilistic seismic hazard analysis (PSHA) by minimizing the subjectivity involved in weight calculation. Guidelines/rules are developed for the weight calculation at each node of the logic tree. Recurrence parameters, magnitude and distance probability distributions, maximum magnitude, and selection of ground motion predictive equations (GMPEs) are considered the possible sources of epistemic uncertainty. A GMPE rule is proposed to be used with the PSHA framework to account for the propagation of epistemic uncertainty. The north-east region of India is chosen for the purpose of illustration. The study region is divided into seven seismic source zones (five in the active crustal region and two in the subduction zone). Seismic hazard is characterized in terms of the weighted mean and fractile representation of hazards using the logic tree approach. Only one sample illustration of the results are reported in terms of weighted mean and fractile representation of hazard curves and uniform hazard spectra (UHS). Further illustration of the PSHA results with possible implications from the epistemic uncertainty is reported in the companion paper. [ABSTRACT FROM AUTHOR]

The author of this paper has recently shown that daily-mean self-potential (SP) time series recorded at Urla station, Turkey, exhibit a unit-root nonstationary behavior with weakly correlated stationary differences driven by stable noise of tail index around 1.12–1.15. This work mainly aims to assess whether the Exponentiated-Exponential Cauchy (EEC) family distributions could be utilized as an alternative to the stable distributions. The EEC family distributions have many advantages as they have closed-form representations. Those goodness-of-fit statistics, relative strengths and predictive abilities of the three EEC family distributions with two- (Cauchy), three- (EEC-3) and four (EEC-4) parameters were compared with that of the stable one. The Akaike Information Criterion (AIC)-based relative strength for the EEC-3 candidate indicated that it is approximately 1.85 times more likely to be the best approximating model than the stable one. Additionally, those considerably smaller relative mean absolute errors (RMAE) for the EEC-3 model indicated that the asymptotic tail properties of the empirical distribution could be better represented in comparison with the stable model. The results of this work revealed, on the example of Urla, that an EEC-3 distribution would plausibly the stable one. We hope the findings of this paper would provide many advantages and facilitate the numerical computations in solving problems arising from the use of stable laws. [ABSTRACT FROM AUTHOR]

Following the first volume (PAGEOPH, 2019, 176, No. 7), twenty-four papers on tsunamis are included in the PAGEOPH topical issue "Twenty five years of modern tsunami science following the 1992 Nicaragua and Flores Island tsunamis: Volume II," reporting on the frontiers of tsunami science and research. The first two papers overview meteorological tsunamis, discussing progress since the 1992 Daytona event, and examining the March 2017 Persian Gulf destructive event. The next four papers review historical tsunami events, starting with a paper providing statistics for the last 120 years. The 2018 Kodiak event is investigated in the following two papers. A set of five papers discusses tsunami-warning methodologies specifically for the Australia and Nankai (Japan) regions, and general tsunami warning approaches. Probabilistic tsunami hazard assessment including case studies for two Australian coasts and the Pacific Coast of Central America, as well as discussion regarding the effect of shallow slip amplification uncertainty, and tsunami hazard assessment for the Port of Ensenada, Baja California, are presented in the next five papers. Two papers discuss tsunami tide interaction, and the following two investigate landslide-generated tsunamis, specifically a tsunami landslide scenario study for the Maltese Islands, and the 1694 Ambon, Indonesia tsunami. Tsunami hydrodynamics studies investigating shoaling on steep continental slopes and transmission of long surface, and tsunami-like waves are presented in the last two papers. [ABSTRACT FROM AUTHOR]

Electrical resistivity tomography (ERT) is a widely used method in geophysical prospecting. In practical applications, the smoothness-constrained least squares method is usually used to invert the apparent data of ERT. Although the resistivity distribution in the detection area can be obtained according to the inversion result, it is difficult to resolve the specific boundary of anomalies directly, which will affect the accuracy of the interpretation results of the detection data. This paper proposes a high-resolution imaging and interpretation method for ERT based on reflection coefficient analysis. This method can amplify the data features at the boundary of anomalies by performing the secondary processing and analysis on inversion results, thereby identifying the specific boundary of anomalies. This research improves the accuracy of interpretation results and realizes high-resolution imaging. Compared with the multi-scale inversion and other methods that enhance the resolution by optimizing the inversion algorithm, this method can more intuitively determine the specific boundary of anomalies in the inversion cross-section. [ABSTRACT FROM AUTHOR]

On February 28th, 1969, a large earthquake (M SB w sb = 7.8) strokes the Iberian Peninsula and northern Morocco, producing some casualties and important damage and economic losses. This earthquake is the last large earthquake that has occurred in this region, very near where the catastrophic 1755 Lisbon earthquake took place. The paper by Udías ([11]) is a review of large tsunamigenic earthquakes that occurred at SW of Iberia before the 1755 Lisbon earthquake. [Extracted from the article]

Twenty papers on the study of tsunamis are included in Volume III of the PAGEOPH topical issue “Global Tsunami Science: Past and Future”. Volume I of this topical issue was published as PAGEOPH, vol. 173, No. 12, 2016 and Volume II as PAGEOPH, vol. 174, No. 8, 2017. Two papers in Volume III focus on specific details of the 2009 Samoa and the 1923 northern Kamchatka tsunamis; they are followed by three papers related to tsunami hazard assessment for three different regions of the world oceans: South Africa, Pacific coast of Mexico and the northwestern part of the Indian Ocean. The next six papers are on various aspects of tsunami hydrodynamics and numerical modelling, including tsunami edge waves, resonant behaviour of compressible water layer during tsunamigenic earthquakes, dispersive properties of seismic and volcanically generated tsunami waves, tsunami runup on a vertical wall and influence of earthquake rupture velocity on maximum tsunami runup. Four papers discuss problems of tsunami warning and real-time forecasting for Central America, the Mediterranean coast of France, the coast of Peru, and some general problems regarding the optimum use of the DART buoy network for effective real-time tsunami warning in the Pacific Ocean. Two papers describe historical and paleotsunami studies in the Russian Far East. The final set of three papers importantly investigates tsunamis generated by non-seismic sources: asteroid airburst and meteorological disturbances. Collectively, this volume highlights contemporary trends in global tsunami research, both fundamental and applied toward hazard assessment and mitigation. [ABSTRACT FROM AUTHOR]

Inspired by the first workshop on Best Practices in Physics-Based Fault Rupture Models for Seismic Hazard Assessment of Nuclear Installations (BestPSHANI) conducted by the International Atomic Energy Agency (IAEA) on 18-20 November, 2015 in Vienna (), this PAGEOPH topical volume collects several extended articles from this workshop as well as several new contributions. A total of 17 papers have been selected on topics ranging from the seismological aspects of earthquake cycle simulations for source-scaling evaluation, seismic source characterization, source inversion and ground motion modeling (based on finite fault rupture using dynamic, kinematic, stochastic and empirical Green's functions approaches) to the engineering application of simulated ground motion for the analysis of seismic response of structures. These contributions include applications to real earthquakes and description of current practice to assess seismic hazard in terms of nuclear safety in low seismicity areas, as well as proposals for physics-based hazard assessment for critical structures near large earthquakes. Collectively, the papers of this volume highlight the usefulness of physics-based models to evaluate and understand the physical causes of observed and empirical data, as well as to predict ground motion beyond the range of recorded data. Relevant importance is given on the validation and verification of the models by comparing synthetic results with observed data and empirical models. [ABSTRACT FROM AUTHOR]

Explains that this issue contains a selection of papers presented in "Geodynamics of the Western Part of the Eurasia-Africa Plate Boundary (Azores-Tunisia)" workshop on May 31 to June 2, 2001 in Cadiz, Spain. Model for the orogenic evolution of the central part of the region; Subduction-subduction-transform fault triple junction in the Betic-Rif orogenic belt; Tectonic deformations in the frontal part of the Rif cordillera and the Sais basin.

10.1007/s00024-020-02508-x 23 Liu B, Kalinowski M, Sun Y, Carrigan CR, Saragiotis C, Wang J, Ertl M, Kijima Y, Schoemaker R, Ku'smierczyk-Michulec J, Tipka A, Kreek S, Antoun T. Characterization of CTBT-relevant radioxenon detections at IMS stations using isotopic activity ratio analysis. Liu et al. ([23]) provides a rigorous mathematical approach to establish the spatial and temporal relationships between a signal created by a nuclear explosion and a radioxenon measurements at an IMS station, including the isotopic activity ratios and their uncertainties. The purpose of the IMS sensor network is to detect signals that are indicative of nuclear explosions, as well as to identify and to locate nuclear explosions underground, underwater or in the atmosphere. The Comprehensive Nuclear-Test-Ban Treaty (CTBT) was negotiated at the Conference on Disarmament in Geneva between 1993 and 1996. [Extracted from the article]

This paper focuses on events linked to controlled underwater explosions of World War 2 (WW2) ordnances which were included in the Reviewed Event Bulletin (REB). Data used for the study were provided by seismic stations of the International Monitoring System (IMS) in 2020. Examined events were triggered by devices of different charge size and took place in several locations in Europe. There were also other, previously detected WW2 ordnance underwater explosions which could be compared to events in 2020. It is shown that these relatively small underwater explosions listed in the REB, with good coupling to the ground, are located by the IMS network within 20 km from the ground truth. Charge size of explosive material was related to event magnitude. Results were compared to magnitudes published for underwater explosions of larger sizes. The conclusion is that an in-water explosion will result in seismic waves with amplitudes equivalent to the amplitudes of seismic waves from an in-ground explosion with 17.2 times the yield in kT. [ABSTRACT FROM AUTHOR]

The International Monitoring System includes a network of radionuclide detectors operated around the world monitoring for nuclear explosions. A key aspect of the International Monitoring System is the detection of radioxenon with a network of stations and laboratories. Beta-gamma detectors are utilized extensively for the detection of radioxenon, and the beta detection is primarily performed with a plastic scintillator cell. Two areas of improvement for plastic scintillator are the sample carry-over ("memory effect") and energy resolution. While the scintillator can be coated to remove the memory effect, the energy resolution must be improved with a different detector material. Silicon is the current leading candidate for the future beta cell material due to the much-improved energy resolution compared to plastic scintillators (factor of ~ 3x). PNNL is developing a silicon beta cell for use as a potential modular replacement within Xenon International (a next generation radioxenon detection system currently undergoing acceptance testing for potential inclusion in the International Monitoring System). The beta cell utilizes four different silicon detectors to create an active volume for the radioxenon within an outer gas cell. Since there are four separate beta signals (compared to one for plastic scintillators), data acquisition modifications are required. In this paper, we detail the design, efficiency measurements, and long-term testing of the silicon beta cell and potential improvements in isotopic discrimination. [ABSTRACT FROM AUTHOR]

Probabilistic seismic hazard assessment of North-East India is carried out considering the GMPE rule and framework developed in the companion paper to account for the propagation of epistemic uncertainty. Seismic hazard is characterized in terms of weighted mean and fractile representation using a logic tree approach. Target conditional spectra with different conditional time periods are estimated by two methods: considering GMPE-specific generalized causal rupture and all contributing causal rupture scenarios. Results are reported with 2475- and 475-year return periods. The ratio of fractile to weighted mean representation of hazard is proposed as an alternative viewpoint of the importance factor used in seismic design. [ABSTRACT FROM AUTHOR]

A preface for the Volume 163 issue of "Pure & Applied Geophysics" is presented.

In recent years the International Atomic Energy Agency (IAEA) has been closely following and supporting the use of physics-based rupture models for ground motion prediction (e.g. IAEA Safety Standards Series No. SSG–9 and Safety Report Series No. 85) as well as for fault displacement prediction (IAEA-TECDOC, in preparation), respectively for applications in Seismic Hazard Analysis (SHA) and Fault Displacement Hazard Analysis (FDHA) for nuclear installations. Further strengthening of this effort and dissemination in practices for SHA, FDHA and engineering issues have been done through different international working group activities, being the most outstanding two international workshops on Best Practices in Physics-based Fault Rupture Models for Seismic Hazard Assessment of Nuclear Installations (BestPSHANI) in 2015 and 2018. A PAGEOPH topical volume for the BestPSHANI 2015 was published in Dalguer et al. (Pure Appl Geophys 174:3325–3329, 2017). Now, in this PAGEOPH topical volume we collect several articles from the BestPSHANI 2018 workshop as well as several new contributions. The issue also covers further topics on the assessments of engineering issues that rely on ground motion estimates for the evaluation of structures oriented to full seismic risk analysis. A total of twenty-nine papers have been selected covering topics ranging from the seismological aspects of earthquake source studies, ground motion and fault displacement modeling to the engineering application of simulated ground motion for the analysis of soil structure interaction, structural response and fragility curve analysis for the quantification of seismic vulnerability of structures and their seismic performance. Collectively, the seismological papers discuss several current issues of source characterization and ground motion prediction for SHA, highlighting the usefulness of physics-based models for future applications in practice. The engineering papers describe methodologies to develop integral models from source-to-structures that consider the developments of synthetic seismograms as input for structural response and fragility curves estimation for seismic vulnerability assessment. Therefore, this issue contents advanced seismological and engineering resources that might be useful to scientists, engineers, students and practitioners involved in all aspects of SHA, FDHA and vulnerability analysis of engineering structures for seismic risk. [ABSTRACT FROM AUTHOR]

This is the second topical volume on 'Recent Advances in Nuclear Explosion Monitoring' that started with Pure and Applied Geophysics Topical Volume 167 (2010), and again reports on the most recent advances in science and technology that have been achieved to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). This progress in the development and testing of new sensor technologies and analysis methodologies in all relevant scientific disciplines improves the capabilities in detection, location and characterization of CTBT-relevant events. In particular, the latter poses a challenge for smaller events, where natural or manmade but CTBT-irrelevant sources can generate false-positive events. The efficient discrimination of these events pursued at a minimum risk of missing a nuclear explosion is the overall challenge. The 29 papers of this volume can be structured into 16 waveform studies, eight in the field of radionuclide monitoring and related atmospheric backtracking, and five papers related to on-site inspection or overhead detection of relevant events, with many of these originally presented at a special session on 'Research and Development in Nuclear Explosion Monitoring' at the most recent annual General Assemblies of the European Geosciences Union. [ABSTRACT FROM AUTHOR]

Introduces a series of papers related to mathematical techniques, modeling, numerical simulations, atmospheric and oceanic processes and field experiments conducted to gain insight into the weather and climate system. Application of the "splitting methods" of numerical modeling to a high resolution model of the Indian Ocean; Numerical experiments designed to determine the fidelity of predictions of major features of the Indian monsoon season; Analysis of the 2002 Colorado drought.

The article reviews the book "Frontiers in Geofluids", edited by B. Yardley, C. Manning and G. Garven.

Because of the scarcity of recorded seismic ground motions from Vrancea intermediate-depth source that can be used in designing a structure, engineers are bound to use scaled, artificial, or simulated accelerograms. Out of these options, the first two might incompletely account for the phenomena that may appear. Although complicated, simulated accelerograms provide one of the best options for defining the seismic demand in engineering design, but further research is needed to adapt the simulation methods to the source, path, and site-specific characteristics. As some parameters used in simulations were not addressed yet specifically for the Vrancea-intermediate seismic source, the specific path duration is investigated in this paper. Using a database with the recorded ground motions from March 4, 1977, August 30, 1986, May 30 and May 31, 1990, October 27, 2004 Vrancea earthquakes (the only five recorded earthquakes with moment magnitudes at least equal to 6), the path and magnitude dependent duration specific to Vrancea intermediate-depth seismic source to be used in the stochastic simulation is developed. [ABSTRACT FROM AUTHOR]

Twenty-two papers on the study of tsunamis are included in Volume II of the PAGEOPH topical issue 'Global Tsunami Science: Past and Future'. Volume I of this topical issue was published as PAGEOPH, vol. 173, No. 12, 2016 (Eds., E. L. Geist, H. M. Fritz, A. B. Rabinovich, and Y. Tanioka). Three papers in Volume II focus on details of the 2011 and 2016 tsunami-generating earthquakes offshore of Tohoku, Japan. The next six papers describe important case studies and observations of recent and historical events. Four papers related to tsunami hazard assessment are followed by three papers on tsunami hydrodynamics and numerical modelling. Three papers discuss problems of tsunami warning and real-time forecasting. The final set of three papers importantly investigates tsunamis generated by non-seismic sources: volcanic explosions, landslides, and meteorological disturbances. Collectively, this volume highlights contemporary trends in global tsunami research, both fundamental and applied toward hazard assessment and mitigation. [ABSTRACT FROM AUTHOR]

For the purpose of monitoring for compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), the International Monitoring System (IMS) is being established that includes 40 sensor systems for atmospheric xenon radioactivity. Its purpose is to monitor the atmosphere for signatures that may indicate a nuclear explosion. Normal operational releases of radioxenon from nuclear facilities can regularly be observed by these very high-sensitive noble gas systems. Existing best estimates of releases for a generic year are unlikely to apply for any specific year at the level of individual facilities because their releases are highly variable and can change by several orders of magnitude from year to year. In this paper, best knowledge of the radioxenon emission inventory from nuclear power plants (NPPs) is collected for the calendar year 2014. The distribution function for each CTBT relevant radioxenon isotope is derived from all releases from NPPs as reported for 2014. The data of this paper can be used for developing and validating methods based on atmospheric transport modelling that are designed to enhance understanding of the impact of known sources on the IMS background observations. [ABSTRACT FROM AUTHOR]

A correction to this paper has been published: https://doi.org/10.1007/s00024-021-02772-5 [ABSTRACT FROM AUTHOR]

The geological activity in Sichuan and Yunnan of China is intense, and large earthquakes such as the Tonghai earthquake in 1970 have caused huge casualties and economic losses. Therefore, it is significant to reduce the long-period earthquake damage of dams and high-rise buildings to reproduce the near-fault long-period ground motion characteristics of the Tonghai earthquake. In this paper, the finite difference method is used to predict the long-period characteristics of the Tonghai Ms 7.8 earthquake. Considering the uncertainty of the initial fracture point, number of asperities, and slip angle, 18 seismic scenarios are established. The predicted results are verified by comparing intensity, attenuation relation and pulse probability distribution. At the same time, based on the velocity pulse recognition method, the pulse probability distribution of the near-field is obtained. We selected six seismic scenarios with high probability from 18 seismic scenarios. Our results show that the spatial distribution and pulse probability distribution of near-field simulated ground motion is significantly affected by the initial rupture positions. After the characteristics of the largest asperity on the fault are determined, the remaining asperities have limited influence on the spatial distribution of simulated ground motion. This study expands the application scope of the finite difference method, which can simulate the seismic intensity characteristics of destructive earthquakes in areas with few seismic records. [ABSTRACT FROM AUTHOR]

The issues related to threats to human safety in post-mining areas are important. This article delineates such threats, focusing mainly on the problem of sinkholes emerging above small old shafts. Small shafts are understood as excavations, most often with a rectangular cross section and a side of 1–3 m and a depth ranging from several meters to several dozen meters. The difficulties with locating small shafts have often been associated with the lack of complete geological and mining documentation. Having gained access to the geological and mining documentation concerning mining activities conducted in the nineteenth century, field research was carried out. LIDAR technology has been proposed as a means of initial evaluation of an area together with a thermal imaging camera to assess if the sinkholes had been formed due to past mining activities. Preliminary results of the study suggest that infrared mapping could be used as a method that could to some extent limit the time-consuming and laborious geophysical studies. The work uses Bell's formula and a numerical method to assess the degree of threat of sinkhole formation on the surface area. According to the results of the studies described in the literature as well as the author's professional experience, the most common cause of the surface hazards in post-mining regions is the lowering of the backfilling material in shafts. Precipitation has a significant impact on such behaviour of backfill. Therefore, this paper proposes methods of isolating shaft's backfilling column from precipitation water. [ABSTRACT FROM AUTHOR]

In this paper, a two-dimensional numerical model for simulating the generation and propagation of tsunami waves caused by upthrust bed movement is developed. To consider the nonlinearity as well as save the computational cost, a Navier–Stokes equation solver is used for the generation zone, and a Serre equation solver is adopted for the downstream evolution of the tsunami waves. The solution of the Navier–Stokes equation solver is extracted and transferred as the initial solution of the Serre solver, which means a one-way coupling is achieved. In this way, a one-way coupled Navier–Stokes-Serre model is obtained. After a detailed validation of the individual solvers, the coupled model is utilized for simulating the generation and propagation of tsunami waves caused by the upthrust bed movement in shallow water of uniform depth. It is found that the coupled model is comparable to the traditional Boussinesq equation model. Finally, the capacity of the coupled model for simulating wave-breaking cases is demonstrated. [ABSTRACT FROM AUTHOR]

The target reliability of mine rock slopes must be scientifically determined, which can fully reflect the safety level of slope stability and plays an essential role in establishing slope reliability design guidelines. Since the design guidelines based on reliability methods have not been established for mine rock slopes, the suggested target reliability values are proposed based on the grey fixed weight clustering and analogy method. Firstly, a new evaluation method of slope safety grade is proposed by considering more influencing factors of slopes. Secondly, the grey fixed weight clustering is used to quantitatively processes the slope reliability data, and the slope safety grade is judged. Then, the target reliability of each grade is obtained by the analogy method. Finally, the equal difference method is applied to set the threshold of allowable failure probability for the minimum service life of slopes, and the reliability of other service life is processed by linear interpolation. The results show that, the target reliability of the maximum service life for grade I, II, III ductile failure is 3.25, 2.75, 2.25, and brittle failure is 3.75, 3.25, 2.75, respectively. the allowable failure probability of the minimum service life for each grade shows that the ductile failure is 1%, 3%, 5% and brittle failure is 0.5%, 1%, 3%, respectively. In addition, the suggested values of Inter-ramp and Bench slopes are also improved, and a case study is conducted in the Jinbao iron mine to illustrate the feasibility of the method and results in this paper. [ABSTRACT FROM AUTHOR]

Twenty-two papers on tsunamis are included in the Pure and Applied Geophysics topical issue "Twenty five years of modern tsunami science following the 1992 Nicaragua and Flores Island tsunamis: Volume I," reporting on the frontiers of tsunami science and research. The first three papers overview significant tsunamis of 1992–2018 and discuss the problems of tsunami cataloguing. The main focus of the next four papers is on specific details of historical tsunami events and field surveys. First, three papers are related to thorough analyses of several historical events based on macroseismic, seismological, and tsunami observations, tide gauge data, and modelling results: the 1907 Sumatra "tsunami earthquake," the 1941 Andaman Islands earthquake, and five great tsunamis in the Pacific Ocean (1946, 1952, 1957, 1960 and 1964). The last paper of the section concerns results of the field survey of the 2017 Bodrum-Kos tsunami. The reconstruction of the tsunami sources is the main target of the four following papers, with four events examined in detail: the historical 1810 Baja California, 1992 Flores Island, 2012 Haida Gwaii and 2015 Chilean (Illapel) tsunamis. A set of three papers address problems associated with landslide-generated tsunamis in three different regions: a modelling of the 2017 landslide and tsunami at Karrat Fjord, Greenland; a probabilistic analysis of the hazard from the Indus Canyon in the NW Indian Ocean; and a study of the landslide-induced tsunami hazard along the US East Coast. The next section, including three papers, reports on comparisons between different types of tsunami models, on numerical modelling of tsunami waves in the Caspian Sea, and on the modelling of magnetic signals at Easter Island, following the 2010 and 2015 Chilean tsunamis. The last group of five papers discusses tsunami hazard assessment and warning for various regions of the world oceans, including Alaska, the eastern and western Mediterranean, Australia, the Northeast Atlantic and the entire Pacific Ocean; one specific aspect of these studies is the compilation and efficient application of observed data, in particular, from DARTs. [ABSTRACT FROM AUTHOR]

The topical issue includes 22 papers on different aspects of meteorology and climatology of the Mediterranean and Black Seas. The papers are grouped into three categories, based on scale analysis of processes, and whether the study is dominantly related to the atmospheric or oceanic phenomenon. The category “Storms, Extremes and Mesoscale Processes” encompasses seven papers, ranging from observation and modelling data analysis of extreme atmospheric (severe winds, hailstorms, waterspout, cyclones) and oceanic (meteotsunamis, surface waves) events, occurring locally, but being connected to wider patterns and processes. The six papers in category “Atmospheric Climate, Variability and Climate Change” contain analyses of long-term observations and climate projection outputs, but also assess atmosphere-ocean-land interactions and cycles, that are important in a climate perspective. The category “Ocean Climate and Variability” includes nine papers, which map ocean processes (sea level variability, circulation, sea surface temperatures, vertical thermal structure, water masses and dense water formation) on a climate timescale, both, in the Mediterranean and Black Sea sub-basins, or taking them as a whole. [ABSTRACT FROM AUTHOR]

Twenty-five papers on the study of tsunamis are included in Volume I of the PAGEOPH topical issue 'Global Tsunami Science: Past and Future'. Six papers examine various aspects of tsunami probability and uncertainty analysis related to hazard assessment. Three papers relate to deterministic hazard and risk assessment. Five more papers present new methods for tsunami warning and detection. Six papers describe new methods for modeling tsunami hydrodynamics. Two papers investigate tsunamis generated by non-seismic sources: landslides and meteorological disturbances. The final three papers describe important case studies of recent and historical events. Collectively, this volume highlights contemporary trends in global tsunami research, both fundamental and applied toward hazard assessment and mitigation. [ABSTRACT FROM AUTHOR]

A trend in the development of geophysics is to seek wave theory closer to the physical reality and derive corresponding wave equations to achieve highly accurate forward modeling, imaging, and inversion of complex structures. The generalized continuum mechanics (GCM) theory enriches the context of the conventional continuum mechanics theory by introducing the additional characteristic length scale parameters to represent the microstructural properties of the medium, and the asymmetric elastic wave equations derived from GCM theory can handle the influence of heterogeneity of a medium caused by the microstructural interactions on the propagation of seismic waves. To date, there are few studies on the numerical and analytical solutions of the elastic wave equations derived from the GCM theory, especially in the frequency band of seismic exploration. In addition, there are few studies in the existing literature that incorporate multiple theories and methods of the GCM theory into an integrated frame. In this paper, we introduce the concept of the multi-scale microstructural interactions and construct the quantitative relationship between the characteristic length scale parameter of the medium and the characteristic length scale parameter of the micro-pore reflecting the micro-pore structures, and then integrate the modified couple stress theory and the one-parameter second strain gradient theory into a unified framework for numerical modeling and analysis. [ABSTRACT FROM AUTHOR]

Greece is a country structured by land, several islands and sea. A regional gravity model of such a country demands the involvement of several types of gravity data in order to cover all its territory. In this paper, we present the development of a regional combined gravity model of Greece and its surrounding area, by integrating terrestrial, marine (shipborne and altimetry-derived gravity data) and satellite data (GOCE and GRACE data). These kinds of data, especially the terrestrial and marine ones, have passed quality and validation control since they were collected from different organizations, which means that they probably have been acquired and processed with different parameters and formulas. Following that, their integration was accomplished with the application of the least-squares collocation (LSC). Therefore, a newly combined regional gravity model of Greece and its surrounding areas has been developed. This gravity model can be valuable for regional geological and geophysical studies of Greece, since it provides homogeneously the distribution of Complete Bouguer anomaly (CBA) all over Greece, with updated gravity data and in good agreement with the initial gravity datasets that have been used. [ABSTRACT FROM AUTHOR]

The evolution of ensemble learning has recently offered a new approach to model complex systems. Inspired by the success of such methods, this paper introduces a new ensemble approach that integrates capabilities of two top state-of-the-art machine learning (ML) methods, namely random forests (RF) and genetic programming (GP), to model and forecast meteorological drought onset and severity. The new method, called gene-random forest (GeRF), follows the same steps of a standard GP systems, but with differences in the generation of initial population of potential solutions. The GeRF was tested to model and predict standardized precipitation evapotranspiration indices (SPEI-3 and SPEI-6) at two meteorology stations in Ankara province, Turkey. We have compared its efficiency to those of a classic autoregressive model as well as standalone RF, GP, and a hybrid ML model, called Bat-ELM, achieving results meaningfully superior to the benchmarks, particularly in the testing data. [ABSTRACT FROM AUTHOR]

In this paper, we discuss the results of laboratory tests and field surveys using ground penetrating radar (GPR) method to detect qanats at the main campus of Shahid Bahonar University of Kerman (SBUK), Iran. The main purpose of laboratory experiments was to explore the optimum frequency of GPR surveys to detect qanats for the subsoil in the study site. We performed a variety of laboratory tests with a 3 GHz antenna to detect qanats (simulated using dielectric empty targets) hosted by sand with volumetric water content (VWC) values in the range 1.5–8%. The depth to each target was progressively increased until either approaching the edges of the sandbox or modelling a qanat depth for which GPR data could not detect the target anymore. The scaling factors were calculated for each test to estimate the maximum depth of detecting qanats as a function of the scaled GPR frequency. The results showed that in areas where the subsoil is dominated by sand, medium-frequency GPR antennas can penetrate to depths of a few tens of meters, but the penetration depth considerably decreases when the soil moisture and/or clay content of the medium increase. Based on the results of laboratory simulations, qanats are detectable at a maximum normalized depth of about 15–17 times of the wavelengths in very dry sands with VWC less than 5% while the detectable range rapidly drops down to less than 3 or 4 times of the wavelengths in more humid sands with VWC of about 8%. We also discuss the results of a few field GPR surveys that were measured using antennas with the 50 MHz and the 250 MHz frequencies in the northwestern part of the study area. The processed GPR images could detect a qanat in the position compatible with the results of previous remote sensing studies performed in the area. The depth to the detected qanat is 13.5 m, which is a little bit beyond the maximum limit predicted by the laboratory tests. [ABSTRACT FROM AUTHOR]

Earthquake engineers continually face challenges in how to implement ridge/hill amplification to transfer predicted peak horizontal acceleration (PHA) near the base using a ground motion prediction equation (GMPE) to the desired location on the ridge to compute the design forces. There are very few relations available for the prediction of 2D ridge amplification only, irrespective of geometry. This paper presents the development of relationships for the prediction of ridge amplification based on the numerically simulated seismic responses of the 2D triangular and elliptical and 3D conical and ellipsoidal ridge models for different shape ratios. The variation in ridge effects with the change of azimuth of a site on a hill is also considered in the development of relationships. The analysis of simulated results revealed very large amplitude and spectral amplifications as well as average spectral amplifications (ASA) in the case of 3D ridges as compared to the corresponding 2D ridges. An increase in ridge amplification with an increase in shape ratio is observed for both the 2D and 3D ridge models. An increase in the fundamental frequency of ridges with an increase in shape ratio is observed for a particular width. The analysis of snapshots of the seismic wave field reveals the need for computation of amplitude amplification and associated strain within the hill mass for a tunnel design. It is concluded that the estimated ridge amplification using earthquake records and standard spectral ratio method gives an overestimate due to the de-amplification at the reference station as well as a false fundamental frequency. The developed relations for the 2D and 3D ridges predict amplitude amplification as well as ASA for a particular value of normalised elevation and shape ratio. These relations can be conservatively used by the field earthquake engineer to predict the PHA at any location on a hill (taking into account the dimensionality and shape of the real hill mass), if the same is available at the base of that hill mass using a GMPE. [ABSTRACT FROM AUTHOR]

Teaching–learning-based optimization (TLBO) is a meta-heuristic algorithm that simulates the process of teacher and student (or learner) interaction in transmitting knowledge. The algorithm is relatively simple to implement, with free-tuning parameters for balancing exploration and exploitation of the solution space. TLBO contains two phases, namely, teaching and learning. In this paper, self-adaptive Gaussian bare-bones TLBO (SABBTLBO) is proposed for improving TLBO and Gaussian bare-bones TLBO (BBTLBO) performance. In the SABBTLBO, Gaussian bare-bones and the original teaching phase in TLBO become more adaptive by a mechanism based on the learner's rank. For the new learning phase, an adaptive scaling factor based on the rank mechanism is used to modify the neighborhood search strategy. A restarted mutation approach is also added in the learning phase. The developed SABBTLBO is compared with six state-of-the-art TLBO variant algorithms for inversion of synthetic multiple self-potential (SP) anomaly sources. The proposed SABBTLBO algorithm is also tested and compared with several algorithms applied for field SP data from different locations in the world including India, Portugal, and Indonesia, using the assumption that SP data are sourced by idealized bodies (simple geometric model or thin sheet model). The inversion of multiple SP anomaly sources using SABBTLBO is used not only for determining the best model parameters, but also their uncertainties. The latter is estimated from the equivalence region of the set of possible solutions via cost function topography evaluation. Significant results were obtained and can be associated with the geology of studied area. [ABSTRACT FROM AUTHOR]

GNSS measurement-based geodetic studies have led to researchers explaining the regional deformation in the Himalaya in terms of arc-parallel shearing and arc-normal compression. Arc-parallel extension is caused by an increase in the shearing rate, which is reflected in the increasing arc-parallel velocities as one moves along-arc away from the arc-center. This has prompted many to recognize the significance of arc-parallel shearing and extension in the Himalayan orogeny. Several researchers have proposed that the arc-parallel deformation is taken up almost entirely by the Karakoram fault system through slip transfer from the Himalayan foothills, though recent studies have provided some evidence of dextral faulting within the Northwest (NW) Himalayan accretionary wedge. In this paper we address this issue by providing topography-derived evidence such as the deviation of the maximum gradient azimuth from the arc-normal along the Himalayan arc to show that obliquity in convergence is a significant controlling factor in shaping the morphology of the Himalayan slopes. Approximately 4 ± 3 mm/year of arc-parallel dextral shear is being accommodated within the accretionary wedge spanning the NW Himalaya (particularly the part in Himachal and Garhwal), which is approximately 55% of the total arc-parallel dextral shear resulting from the ongoing convergence between southern Tibet and the Indian Plate in this portion of the Himalaya. The study further suggests consistency of the observed Himalayan deformation with the oblique convergence model and the significant role that the underthrusting ridges inherited from the Indian Plate are playing in the strain accommodation pattern in the overlying Himalaya. [ABSTRACT FROM AUTHOR]

The Lebanese Restraining Bend is an active bend along the Dead Sea Transform Fault in the eastern Mediterranean region where several destructive earthquakes have occurred throughout history. In this paper, we assess the gross features of the seismic hazard of the Lebanese Restraining Bend by applying a neo-deterministic method that involves the generation of synthetic seismograms distributed on a regular grid over the study area. We use the regional seismicity, seismic source zones, focal mechanism solutions, and velocity structural models. We present maps of ground displacement, velocity, and acceleration. This is the first study that generates neo-deterministic seismic hazard maps for the Lebanese Restraining Bend using representative ground motion modeling. Our results show that displacement values of 15–30 cm and velocity values of 30–60 cm/s can be expected along most of Lebanon. In addition, 0.15–0.30 g acceleration values can dominate most of the Lebanese territory and surrounding areas. It is evident from these results that the study area in general and Lebanon in particular constitute a high seismic hazard area, which necessitates further attention from the authorities regarding the precaution measures needed to mitigate the effects of potential catastrophic seismic events; in addition, more detailed investigations are needed at local scale for specific sites of interest. [ABSTRACT FROM AUTHOR]

Large-magnitude earthquakes in northern Chile and southern Peru occur every 108 years on average. It should be noted that over 143 years since the catastrophic earthquake of May 9, 1877, any similar events were completely absent. In 2007, a 7.7 Mw earthquake occurred near Tocopilla, and in 2014 a catastrophic M = 8.1 earthquake hit Pisagua. It is believed that only part of the energy accumulated over 143 years has been released during those events, while most of it is yet to be released. Thus, we can conclude that a serious tsunami hazard exists for all coastal cities of southern Peru and northern Chile. In this paper, on the basis of the available historical data and geodynamic studies, numerical simulation of the historical catastrophic earthquake and tsunami of May 9, 1877 is carried out assuming the blockwise earthquake source configurations. We implemented 23 simulation scenarios for different kinematic behavior patterns of such a source, sequentially updating the source fragmentation to reduce the misfit between the simulated and observed wave height data. Using the proposed methodology, for each scenario, the generation of a tsunami source is simulated and the computation of wave fields up to the 5-m isobath is carried out. The results obtained are compared with historical data. Analysis of the entire set of simulated earthquake scenarios makes it possible to choose a tsunamigenic earthquake scenario with the most adequate characteristics of tsunami waves in the coastal zone. [ABSTRACT FROM AUTHOR]

China suffers severe continental earthquakes. The 2008 Wenchuan earthquake (Ms 8.0) and the 2014 Ludian earthquake (Ms 6.5) are two representative examples from the modern era. The Wenchuan earthquake caused considerable economic losses, and the Ludian earthquake caused unexpected losses with only moderate magnitude. Based on disability-adjusted life years (DALYs), this paper first calculates aggregated disaster losses and the contributions of three factors: number of deaths or missing persons, number of people affected, and direct economic losses. Then, the losses per unit energy released or area affected are calculated for each earthquake to investigate which of the two earthquakes caused more damage. The paper finishes by investigating the implications and revealing three results. (1) The Wenchuan earthquake induced more damage than the Ludian earthquake, but the latter had relatively higher losses per unit energy than the former. (2) Injuries and affected people contributed most to the total losses for each earthquake, more than fatalities or direct damage. This outcome means that unnoticed aspects have the most severe disaster impacts. In addition, long-term impacts of earthquakes are more serious than usually acknowledged, and more attention needs to be paid to these. (3) The damage from moderate earthquakes can exceed expectations, meaning that disaster mitigation policies in all regions are necessary, regardless of the degree of anticipated hazard. [ABSTRACT FROM AUTHOR]