Seismic Epicenters Research Articles

Analysis of Spatial Clustering of Seismic Events by the DPS Topological Filtering Algorithm: Lake Baikal Region

The paper presents the results of applying the Discrete Perfect Set (DPS) topological filtering algorithm to analyze the spatial clustering of seismic epicenters in the Lake Baikal region. The study utilizes earthquake data recorded by the seismic network of the Baikal Branch of the Geophysical Survey of the Russian Academy of Sciences within the latitude range 48°N, 58°N and longitude range of 99°E, 122°E for the period from 1964 to 2018. Clustering characteristics are obtained for (i) the recording period from 1989 to 2018 with varying parameters of the DPS algorithm and four levels of the minimum energy class KР of seismic events and (ii) six non-overlapping time intervals from 1964 to 2018 and seismic events of energy class KР ≥ 8.6 with fixed parameters of the DPS algorithm. The dynamics of the clustering parameters from 1964 to 2018 may characterise the variability of the seismic regime of the region. Specifically, the decrease in the linear size of the areas of identified epicenter groups from about a thousand km to tens km may indicate a significant change in the seismic regime of the Lake Baikal region at the end of the 1990s and the beginning of the 2000s compared to the period between 1964 and 1997.

Extract and analysis of surface deformation caused by Mengyuan earthquake in Qinghai using ascending and descending tracks D-InSAR technology

Precision in uncovering the seismic source mechanism and conducting a thorough monitoring of deformation characteristics resulting from surface rupture is of paramount importance for geological comprehension, disaster management, and emergency response. This study employs both ascending and descending orbit Sentinel-1 data to capture the horizontal and vertical deformation traits of the Ms6.9 earthquake in Menyuan, Qinghai, on January 8, 2022, consequently exposing its seismogenic structure. The research outcomes suggest: the Menyuan earthquake generated an elliptical deformation zone measuring 30 × 20 km, with the maximum line-of-sight seismic displacement reaching 6.8 cm. And then, the vertical deformation field exhibited a range between -0.28 m and 0.42 m, while the horizontal deformation field ranged from -0.89 m to 0.94 m. This indicates that the earthquake's deformation is primarily oriented in the east-west direction. The left plate exhibited an upward trend with a NWW orientation, while the right plate displayed a downward trend with a SEE orientation, suggesting that the Menyuan earthquake can be classified as a "NWW-SEE" type. Furthermore, the seismic epicenter of this earthquake was predominantly concentrated in the western segment of the Lenglongling Fault. Two powerful earthquakes sequentially struck along this fault zone, intensifying the imperative for seismic geological research in the region. Additionally, this instance can serve as a benchmark for monitoring deformations and elucidating the seismic source mechanism in earthquakes with comparable seismogenic structures.

Modelling and assessing seismic resilience of critical housing infrastructure system by using dynamic Bayesian approach

Seismic resilience, the ability of urban housing infrastructure to withstand and recover from seismic events, is of paramount importance in regions prone to earthquakes. Infrastructure systems are frequently harmed by different natural calamities. Despite the high degree of unpredictability in these risks, infrastructure may be made more dependable, resilient, and recoverable using the notion of resilience. This study uses DBN (Dynamic Bayesian Network) to quantify the time-varying resilience of critical housing infrastructure against seismic risks. It creates a methodology to measure seismic resilience and applies it to a real-world case study region, such as Tokyo and Kyoto in Japan, located in one of the world's most seismically active regions. All the resilience parameters under housing infrastructure against seismic resilience are selected, and information about the linked factors of the parameters are collected through literature and experts' opinion. Then using certain methods, the seismic resilience values for various time periods are computed. Eventually, this study examines the end resilience scenarios and attributes of two cities in Japan. Additionally, the resilience values for various time periods of each area of both cities are evaluated. The findings of the study demonstrate the dynamic nature of seismic resilience. In the pre-disaster phase, the housing infrastructure exhibited substantial resilience, with attributes such as rapidity, redundancy, and resourcefulness exceeding 80%. However, the occurrence of seismic events, particularly a heavy earthquake, resulted in a temporary decline in resilience. The post-earthquake period saw rapid recovery efforts, which contributed significantly to the restoration of resilience levels. Ultimately, the resilience levels exceeded the pre-disaster values, highlighting the efficacy of preventive measures. Upon examining five distinct time intervals, it becomes evident that the initial resilience levels (aligned with time slice 0) for Tokyo and Kyoto were documented at 0.85 and 0.90, respectively. However, subsequent to the manifestation of a seismic hazard (represented by time slice 1), these resilience values underwent significant reductions, plummeting to 18.82% for Tokyo and 15.56% for Kyoto. A comparative analysis between Tokyo and Kyoto (between time periods 1 to 4) further highlights the critical role of geographic location in resilience planning. Tokyo, being in closer proximity to seismic epicenters, experienced a significant resilience drop of 26.1% during a heavy earthquake, while Kyoto, situated farther away, demonstrated a 21.05% decline. These findings underscore the need for tailored resilience strategies based on risk exposure. Finally, with the help of evaluated resilience values, resilience maps for various time periods are prepared using ArcMap software to get a clear scenario against seismic hazards of both cities. The quantified resilience values will help the public authorities, stakeholders, and decision-makers to make decisions based on resilience with the assistance of this comparison and the assessed values of seismic resilience.

Geothermal Spatial Potential and Distribution Assessment Using a Hierarchical Structure Model Combining GIS, Remote Sensing, and Geophysical Techniques—A Case Study of Dali’s Eryuan Area

The assessment of geothermal potential has gained prominence among scholars, with a focus on establishing a reliable prediction model to reduce development risks. However, little attention has been given to predicting and evaluating the geothermal potential in Dali’s Eryuan area. This study introduces a novel hierarchical model integrating remote sensing, a Geographic Information System (GIS), and geophysics for the first-ever effective prediction of geothermal potential in Eryuan. The dataset includes lithology, seismic epicenter data, fault distribution, Bouguer gravity anomalies, SRTM-DEM images, and Landsat 8 remote sensing images. These datasets are converted into evidence maps and normalized to generate distinct evidence factor layers. Using the Analytic Hierarchy Process (AHP), a hierarchical model establishes weights for each evidence factor, resulting in a comprehensive prediction map. The results reveal the overall favorable geothermal potential in Eryuan, except the central area. Key hotspots include the Niujie–Sanying–Gromwell Lake and Liantie–Qiaohou, followed by the Youshou, Dengchuan, and Xixiang towns. Validation against known hot springs confirms the model’s accuracy and reliability.

Plio-Quaternary strike-slip tectonics in the Central Mallorca Depression, Balearic Promontory: Land–sea correlation

The Balearic Promontory (Spain) is of key importance to understand the tectonic kinematics of the westernmost Mediterranean, because its continued marine sedimentation has recorded the contrasting effects expected from competing geodynamic models proposed for the region. Near the center of this promontory, between the islands of Mallorca and Ibiza, the Miocene to Pleistocene stratigraphy of the Central Mallorca Depression presents an ideal record of the tectonic deformation that has received only limited attention. We use a widespread dataset of 2D seismic reflection profiles to identify, interpret and map the main prominent reflectors and extrapolate the thickness of the pre-Messinian and Pliocene-Quaternary sedimentary units. We then quantify the timing and style of deformation related to the various fault systems. Our results reveal for the first time a series of aligned small depressions bounded by extensional and strike-slip faults and filled with Plio-Quaternary sediment, perfectly aligned with the sub-basins of the onshore Mallorca Graben. A subsidence analysis confirms this correlation. We identify non-cylindrical deformation within the Plio-Quaternary unit that is remarkably similar to that observed onshore, suggesting continuous fault zones from the Central Mallorca Depression to Mallorca Island. We interpret an intra-PQ unconformity as the marker of a transition from extensional to strike-slip tectonic regime. The strike-slip stage is represented by both transpressional and transtensional structures, interpreted as restraining/releasing bends respectively and step overs along the faults. We show that these offshore faults in the Central Mallorca Depression overlap well with seismic epicenters and suggest major active strike-slip corridors that have an onshore continuity both until eastern Mallorca and in the southwestern Ibiza margin. The role of previous tectonic inherited structures (rifting, Betic thrusts, post-orogenic collapse) on the deformation reported here is discussed and we propose a tentative sketch that integrates our results in a Miocene to Present-day evolution at regional scale.

Associations Between Strong Earthquakes and Local Rainfall in China

Strong earthquakes are a major cause of natural disasters and may also be related to heavy rainfall events. Both phenomena have received considerable attention in seismology and meteorology, two relatively independent disciplines, but we do not yet know whether there is a connection between them. We investigated the characteristics of daily rainfall over seismic areas in China. Our statistical analyses showed that there is a strong correlation between strong earthquakes (Ms ≥ 6.0) and rainfall over the seismic area, with 74.9% of earthquakes in China accompanied by seismic epicenter rainfall and 86.6% by seismic area rainfall. The statistics also showed that the daily precipitation over the seismic area, including the epicenter, was mainly light rain, with only a few instances of torrential or storm rain, with 80% of the rainfall events lasting two or more days. The maximum cumulative precipitation corresponded well with the strong earthquakes occurring over steep terrain, such as the Taiwan central mountains and the eastern Tibetan Plateau. The earthquake area rainfall had a higher frequency than the 30-years climatological average and was dominated by earthquake events in the wet season. The WRF-ARW numerical simulation of seismic local rainfall during the devastating Ms 8.0 Wenchuan earthquake in May 2008 showed that the geothermal heat from the earthquake strengthened the local convergence of moisture and vertical motion near the epicenter and the upward transport of the sensible heat flux, which favored seismic rainfall. The results of this study show that rainfall in the seismic area is closely related to strong earthquakes and can be triggered and enhanced by geothermal heat.

Exploiting Real-time Search Engine Queries for Earthquake Detection: A Summary of Results

Online search engine has been widely regarded as the most convenient approach for information acquisition. Indeed, the intensive information-seeking behaviors of search engine users make it possible to exploit search engine queries as effective “crowd sensors” for event monitoring. While some researchers have investigated the feasibility of using search engine queries for coarse-grained event analysis, the capability of search engine queries for real-time event detection has been largely neglected. To this end, in this article, we introduce a large-scale and systematic study on exploiting real-time search engine queries for outbreak event detection, with a focus on earthquake rapid reporting. In particular, we propose a realistic system of real-time earthquake detection through monitoring millions of queries related to earthquakes from a dominant online search engine in China. Specifically, we first investigate a large set of queries for selecting the representative queries that are highly correlated with the outbreak of earthquakes. Then, based on the real-time streams of selected queries, we design a novel machine learning–enhanced two-stage burst detection approach for detecting earthquake events. Meanwhile, the location of an earthquake epicenter can be accurately estimated based on the spatial-temporal distribution of search engine queries. Finally, through the extensive comparison with earthquake catalogs from China Earthquake Networks Center, 2015, the detection precision of our system can achieve 87.9%, and the accuracy of location estimation (province level) is 95.7%. In particular, 50% of successfully detected results can be found within 62 s after earthquake, and 50% of successful locations can be found within 25.5 km of seismic epicenter. Our system also found more than 23.3% extra earthquakes that were felt by people but not publicly released, 12.1% earthquake-like special outbreaks, and meanwhile, revealed many interesting findings, such as the typical query patterns of earthquake rumor and regular memorial events. Based on these results, our system can timely feed back information to the search engine users according to various cases and accelerate the information release of felt earthquakes.

On the biophysical mechanism of sensing upcoming earthquakes by animals

It is documented that a few days or weeks before major Earthquakes (EQs) there are changes in animal behavior within distances up to 500 km from the seismic epicenter. At the same time Seismic Electric Signals (SES), geomagnetic and ionospheric perturbations, are detected within similar distances. SES consist of single unipolar pulses, and/or groups of such pulses called “SES activities” with an average frequency between successive pulses on the order of ~0.01 Hz and electric field intensity on the order of ~10−5–10−4 V/m (Frazer-Smith et al., 1990; Rikitake, 1998; Varotsos et al., 1993, 2011, 2019; Hayakawa et al., 2013; Grant et al., 2015). We show that the SES activities can be sensed by living organisms through the “Ion Forced-Oscillation Mechanism” for the action of Electromagnetic Fields (EMFs) on cells, according to which polarized EMFs can cause irregular gating of electro-sensitive ion channels on the cell membranes with consequent disruption of the cell electrochemical balance (Panagopoulos et al., 2000, 2002, 2015). This can be sensed by sensitive animals as discomfort in cases of weak and transient exposures, and may even lead to DNA damage and serious health implications in cases of intense exposure conditions (as in certain cases of man-made EMF exposures). Moreover, we show that the geomagnetic and ionospheric perturbations cannot be sensed through this mechanism. The same mechanism has explained meteoropathy, the sensing of upcoming thunderstorms by sensitive individuals, through the action of the EMFs of lightning discharges (Panagopoulos and Balmori, 2017). The present study shows that centuries-long anecdotal rumors of animals sensing intense upcoming EQs and displaying unusual behavior, lately documented by systematic studies, are now explained for the first time on the basis of the electromagnetic nature of all living organisms, and the electromagnetic signals emitted prior to EQs.

STUDY OF TEC VARIATIONS USING PERMANENT STATIONS GNSS DATA IN RELATION WITH SEISMIC EVENTS. APPLICATION ON SAMOTHRACE EARTHQUAKE OF 24 MAY 2014

This study investigates the ionospheric total electron content (TEC) variations prior to the earthquake (MW = 6.9) of 24 May 2014 in Samothraki island of north Aegean Sea in Greece. TEC estimates were analyzed using data from GNSS (GPS+Glonass) permanent networks with the aim to detect possible ionospheric anomalies associate with the seismic event. The test period covers one week of data, 4 days before and two days after the event. Selected GNSS stations are scattered around seismic epicenter of distances from 16 up to 1375 km. TEC values estimated for every hour using PPP technique with Bernese GPS software. A comparison with global TEC estimates derived from CODE and JPL institute confirms the validation of results. It is found that a significant decrease 1-day prior to earthquake occurs at all of the selected stations. This result is not obvious when standard ionospheric model is performed for the estimation of TEC. Therefore, in such cases the use of dedicated GNSS processing data scenario is mandatory. A spatial analysis on TEC estimates with geometrical properties shows that the 1-day decrement is related with the EQ shock and may point the location area of the Earthquake. Finally, we conclude that the lithosphere-atmosphere-ionosphere coupling (LAIC) mechanism through acoustic or gravity waves has a key role for this phenomenology.

Сейсмологические наблюдения в Антарктиде

The history of seismological observations development in Antarctica is shown. Maps of the existing seismic stations and earthquake epicenters location on the mainland territory for the instrumental monitoring period (1956–2018) are presented according to data from International centers. Russian seismic stations monitor major earthquakes around the globe, earthquakes in the seismic zone around Antarctica, and local seismic phenomena in Antarctica, including local earthquakes and ice sheet ruptures. Since 1999, the Novolazarevskaya seismic station has been equipped with digital equipment. An analysis of the sixth continent seismicity was made; the records of the Antarctic strongest earthquakes (2007, 2008, and 2012) by the GS RAS stations Mirny and Novolazarevskaya were shown.

Significant ELF perturbations in the Schumann Resonance band before and during a shallow mid-magnitude seismic activity in the Greek area (Kalpaki)

Strong ELF perturbations in the Schumann Resonance band (0–50 Hz) were detected in the North of Greece close to the village of Kalpaki during a shallow (17 km) mid-magnitude earthquake (5,3R) and the post-seismic sequence that followed it. The observation site was serendipitously located almost above the main quake epicenter (3,65 km away). It is probably the first time that such a detailed recording of ELF electromagnetic emission of lithospheric and/or ionospheric origin was obtained so close to a seismic epicenter. This event is very significant in the study of the interaction between seismic waves and ELF electromagnetic radiation. It will certainly contribute to the understanding of that interaction, and may even lead to more accurate earthquake predictions.

GNSS Data Processing and Analysis for Earthquake Disaster Prevention Monitoring

This article describes how an earthquake with highest magnitude 5.8 on the Richter scale occurred in the Gyeongju area on Sep. 12, 2016 since the first seismological observation. In addition, continuous aftershocks have occurred. There is a pressing need for proper earthquake monitoring and prevention systems. This article is intended to apprehend the dislocation and location change of Continuously Operating Reference Station (CORS) caused by earthquake by means of data on CORS of the National Geographic Information Institute (NGII) and suggest effective seismic monitoring methods. Through Precise Point Positioning (PPP) over earthquake occurrence locations, it was possible to determine the dislocation aspects of CORS for TEGN and CHSG near the seismic epicenter. The nationwide Relative Positioning processing of data for 58 CORS from Sep. 1 to Sep. 30 suggested that CORS had not transitioned coordinates due to the earthquake. For the sake of more efficient earthquake observation and monitoring, it is believed that highly frequent GNSS data acquisition and the additional installation of observation devices such as seismometers is required.

Монгол орны нутал дэвсгэрт бүртгэгдсэн газар хөдлөлтийн төвүүдийн нягтаршил

Map of earthquake epicenter density of Mongolia for the instrumental period (1964 - 2000) is presented. Seismic active zones are studied using information provided by the location of earthquake epicenters density. The results suggest that Mongolian territory could be divided into five seismic active and homogeneous sub- zones originated by the distribution of seismic active Cenozoic faults and epicenter density. Earthquake epicenter density and its spatial distribution are given a possibility to define and localize seismic active zones, current seismic pattern and its future dynamics of seismic activity in these zones. Most of earthquakes with the larger magnitude in the seismic active zones occurred in proximity to the statistically identified potential faults. Results of this study would be input parameters of seismic hazard assessment study of urban areas.

DIGITAL ENGINEERING GEOLOGICAL MAP OF THE ATHENS PREFECTURE AREA AND RELATED DATABASE MANAGEMENT SYSTEM

A digital engineering-geological map of the Athens Prefecture area was compiled at an original scale of 1:10.000 by IGME in cooperation with Engineering Geology Laboratory of Patras University. The map is related to a database management system constructed according to the project’s special needs, including geotechnical and geological data mainly obtained by boreholes and trial pits. The main map (11 sheets) is accompanied by three thematic maps at an original scale 1:50.000 (hydrogeological, tectonic) and 1:250.000 (seismic epicenters map). It constitute a basic tool for every activity of the Prefecture’s services, in relation to urban development, civil and environmental protection policy, sustainable management of natural resources, continual data supply to citizens and to the technical world. The main advantage of the digital map is the ability of constant updating of the related database, while this procedure should be established to serve social needs. As the mapping was based on a combination of conventional geological mapping techniques and the information from geotechnical database, it is considered to provide useful information for planners and decision makers at a preliminary planning level.

Seismicity and neotectonic uplift in the Augrabies Falls National Park, Namaqualand, Northern Cape, South Africa

Gneissic rocks in the Augrabies Falls National Park are part of the Proterozoic Namaqua-Natal mobile belt. Finding neotectonic evidence in old terranes is always not an easy task. In South Africa, the mid-Miocene is believed to be the beginning of neotectonics. This study investigated the occurrence and recurrence of earthquake activity, occurrence of faulting, jointing, uplift, and potholes in the gneisses cropping out around the Augrabies Falls area that may account for neotectonics. A historic seismic event obtained from the United States Geological Survey (USGS), and seismic epicenters downloaded in October 2015 from IRIS earthquake browser and overlaid on a satellite image with digitised faults and lineaments, indicates that the area is seismically active and is a zone of seismic risk. Potholes occurring today on a dry surface at approximately 613 m above sea level are a direct consequence of the Griqualand-Transvaal neotectonic uplift, which generated a major fault along which water flows continuously. It is concluded that the Augrabies Falls National Park area is a zone of neotectonics. This zone should not be considered for the storage of nuclear wastes.

The 22 February 2014 Mw 4.1 Bordj-Menaiel Earthquake, Near Boumerdes-Zemmouri, North-Central Algeria

A number of destructive earthquakes have occurred in the region of Algiers, the capital of Algeria. Two well‐known historical earthquakes were recorded in 1365 and 1716 (Harbi et al. , 2004). A more recent one, the 2003 M w 6.9 Boumerdes earthquake (also called the Zemmouri earthquake), took place in the Boumerdes district (Fig. 1), about 50 km east of Algiers (Yelles‐Chaouche et al. , 2003). The Boumerdes earthquake occurred on a blind‐thrust fault offshore from the Algerian coast. The rupture was along a northeast–southwest‐striking fault plane, although the precise fault trace was unknown. During this earthquake, an average value of 55 cm of uplift of the shoreline was observed (Meghraoui et al. , 2004), consistent with the thrust focal mechanism, at least in the high‐slip region on the fault plane (Semmane et al. , 2005). Figure 1. The studied area and location of stations that recorded the earthquake used in this study (closed triangles are broadband stations and open triangles are one‐component short‐period stations). Dots show the seismic epicenters from 1992 to March 2014; the 2003 Boumerdes epicenter is represented by the black star, and the Bordj‐Menaiel earthquake is represented by the white star. The black lines are active faults mapped by Guemache (2010). The inset shows the basement in the region in gray. The locations of the numbered blocks 1 and 2 coincide with the two asperities found in the slip distribution models and also with the uplift zones (two thick lines on the coast). More recently, in the same district (Boumerdes), an earthquake of moment magnitude M w 4.1 ( M d 4.3) occurred on 22 February 2014 at 20:30 local time, 12 km southeast of the epicenter of the 2003 Boumerdes earthquake, and at a depth of 7–11 km. The epicenter was located 5 km northeast of the central part of the town of Bordj‐Menaiel and …

Volcanic signatures in time gravity variations during the volcanic unrest on El Hierro (Canary Islands)

AbstractGravity changes occurring during the initial stage of the 2011–2012 El Hierro submarine eruption are interpreted in terms of the preeruptive signatures during the episode of unrest. Continuous gravity measurements were made at two sites on the island using the relative spring gravimeter LaCoste and Romberg gPhone‐054. On 15 September 2011, an observed gravity decrease of 45 μGal, associated with the southward migration of seismic epicenters, is consistent with a lateral magma migration that occurred beneath the volcanic edifice, an apparently clear precursor of the eruption that took place 25 days later on 10 October 2011. High‐frequency gravity signals also appeared on 6–11 October 2011, pointing to an occurring interaction between a magmatic intrusion and the ocean floor. These important gravity changes, with amplitudes varying from 10 to −90 μGal, during the first 3 days following the onset of the eruption are consistent with the northward migration of the eruptive focus along an active eruptive fissure. An apparent correlation of gravity variations with body tide vertical strain was also noted, which could indicate that concurrent tidal triggering occurred during the initial stage of the eruption.

Morphometric characterization of a large scale rockslide, and probable seismogenic origin of landslides on the western flank of Central Precordillera, Argentina

The distribution of late Pleistocene to Holocene rockslides in the western flank of the eastern mountain ranges of Central Precordillera (30° 40′–31° S), has been analyzed to determine the triggering mechanisms. The mode of failure was determined to be translational sliding. This paper presents the results of research on one of the Holocene rockslides located in the western flank of Sierra de La Dehesa, which is composed of stratified limestones of early Paleozoic age. In order to characterize this slide, high resolution satellite imagery interpretation was carried out, along with the recognition of the landslide detachment zones and landslide bodies with the aim of reconstructing the pre-slide topography. The model proposed for this slide is a translational or planar slide, as the mode of failure was along a broadly planar surface accompanied by shear or tensile fractures and joints. The estimated rock volume involved is 1.24 Mm3. We compared rockslide occurrence patterns to slope, topography, lithology, geological structures, and seismicity records. After analysis of the spatial relationships among all the slides and the distribution of seismic epicenters, historical earthquakes and neighboring Quaternary faults as seismogenic sources, we hypothesize that these Quaternary rockslides in the Central Precordillera have been triggered by shallow seismicity associated with active faults.

Theory and detection scheme of seismic EM signals transferred into the atmosphere from the oceanic and continental lithosphere

Due to the compound structure of the medium and large portions of energy transferred, a seismic excitation in the oceanic or continental lithosphere disturbs all types of geophysical fields. To investigate the problem of electromagnetic (EM) disturbances in the atmosphere from the seismically activated lithosphere, we have formulated two mathematical models of interaction of fields of different physical nature resulting in arising of the low-frequency (from 0.1 to 10Hz by amplitude of a few hundreds of pT) EM signals in the atmosphere. First we have considered the EM field generation in the moving oceanic lithosphere and then in the moving continental one. For both cases, the main physical principles and geological data were applied for formulation of the model and characteristics of the computed signals of different nature agree with measurements of other authors. On the basis of the 2D model of the seismo-hydro-EM-temperature interaction in the lithosphere–Ocean–atmosphere domain, a block-scheme of a multisensory vertically distributed (from a seafloor up to the ionosphere) tsunami precursors’ detection system is described. On the basis of the 3D model of the seismo-EM interaction in a lithosphere–atmosphere domain, we explain why Prof. Kopytenko (Inst. IZMIRAN of Russian Acad. Sci.) and co-authors were able to estimate location of the future seismic epicenter area from their magnetic field measurements in the atmosphere near the earth’s surface.

Nonlinear evolution of the atmosphere above a seismic epicenter: 1. Analytical estimates

The spatiotemporal atmospheric variations are studied, and the nonlinear effects above seismic epicenters are revealed. An analytical description of the acoustic pulse nonlinear evolution for a situation when earthquakes with a magnitude larger than M = 4–5 and surface explosions with an energy higher than 30–1000 t equivalent yield affect the atmosphere has been obtained based on the Landau-Whitham method. A comparison of seismic data and data on air explosions made it possible to obtain a formula for estimating the fraction of the earthquake energy released into the atmosphere. The seismic phenomena have been characterized based on the value of the nonlinear effects originating in the atmosphere.