Earthquake Preparation Research Articles

Dynamics of medium-deep seismicity parameters before large earthquakes in South Asian seismic focal zones

The study was continued to reveal the spatio-temporal relationship between strong crustal shocks and the moderate, medium-deep seismicity that precedes them. In the area of preparation of these shocks, the following regularities were revealed: in space – the presence of a high creepex gradient (in particular, the boundary transition between its positive and negative anomalies), in time – a direct correlation of the graphs MS(t) and Cr(t), indicating the creation in the period of preparation of the source under the conditions of a strictly determined influence of the source-size on creepex. Since the proportional dependence of the creepex on the geometric size of the source is usually associated with an increased heterogeneity of the medium in the source, it can be assumed that the processes of brittle fracture of blocks of the undercutting crust coexist here with the processes of inflow of deep mantle material, which ensures the heterogeneity of the properties of the medium in the area of preparation of large earthquakes in the South Asian subduction zones. This conclusion is confirmed on the average creepex anomaly maps by the presence of their increased gradient in the deep region of the preparation of these events.

Vertical deformation before and after the 2022 Menyuan Ms6.9 earthquake and analysis of earthquake precursors

This study analyzed the vertical deformation before and after the 2022 Menyuan Ms6.9 earthquake in Qinghai Province, China, using leveling profiles across faults measured from Minle County in Gansu Province to Menyuan County in Qinghai Province. Our results suggest the following: (1) The amplitude of regional vertical differential motion near the Sunna-Qilian and Lenglongling faults within the Qilian Shan increased before the 2022 Menyuan earthquake. It was accompanied by the emergence of high gradient deformation zones. Deformation at the Tongziba cross-fault leveling site near the Sunan-Qilian fault was considerable. In contrast, deformation at the Daliang cross-fault leveling site near the stepover region (adjacent to the epicenter) between the Lenglongling and Tuolaishan faults was minor. After 2018, vertical deformation at the Tongziba site notably accelerated, while that at the Daliang site was insignificant. (2) After the 2022 Menyuan earthquake, 140–150 mm of subsidence deformation occurred near the Daliang site, while the Tongziba site did not experience significant deformation. (3) Vertical deformation before and after the 2022 Menyuan earthquake conforms with the elastic-rebound theory, and the evolution of pre-earthquake deformation was consistent with the strike-slip fault deformation pattern at different seismogenic stages, i.e., the relative motion near the locked fault in the late seismogenic stage gradually weakened. The characteristics of strain accumulation and release derived from the vertical deformation before and after the Menyuan MS6.9 earthquake help understand the deformation process of earthquake preparation and earthquake precursors.

Weak Seismicity and Strongest Earthquakes Against the Background of the Variations of <i>S</i>-wave Attenuation Field

The paper considers the role of relatively weak earthquakes as a tool for studying the environment, including of strong earthquake process. The spatial structure of the attenuation field of several seismically active regions (of the Garm prognostic polygon in Tajikistan, Altai, the Caucasus, Eastern Anatolia, the Western Tien Shan), as well as the epicentral regions of a number of strong earthquakes, and the confinement of deepened seismicity to it are considered. It is shown that the attenuation field obtained from the short-period code of weak earthquakes in seismically active regions is inhomogeneous and consists of blocks with a high Q factor and weakened zones of strong attenuation. An uneven distribution of deepened earthquakes is noted. It is associated with the block structure: in weakened zones, their share is greater than in blocks with a high Q factor. Examples of variations in the of deepened seismic activity in weakened zones are demonstrated. It varies over time, increasing before strong earthquakes. Facts are presented that testify to the existence of a relationship between the Earth’s rotation rate and the activity of deepened seismicity. Examples are given of the activation of weak seismicity in the form of seismic swarms (series of weak earthquakes concentrated in space and time) in connection with strong events. A characteristic feature of these swarm series is the isometry of the earthquake localization areas in plan view and vertical elongation. As a rule, they coincide with weakened zones of strong absorption of S-waves. Intense localized seismicity, confined to one-dimensional volumes, is most likely associated with increased conductivity channels through which deep fluids migrate. The activation of swarm series is the result of active migration of deep fluids and an increase in fluid saturation of weakened zones. Fluids, in turn, are a catalyst for processes that lead to a decrease in the strength of rocks and the destruction of blocks in epicentral zones. In this case, the clusters to which the swarm series belong can be considered as local seismogenic zones. The appearance of compact isometric in plan and nearly vertical in section clusters of weak seismicity is often observed outside the epicentral zones of strong earthquakes. Such zones may simply be indicators of the seismotectonic situation in the region as a whole. It is assumed that a sharp change in the dynamics of atmospheric pressure during the preparation of a strong earthquake at hydrometeorological stations located in such areas is a consequence of the intergeospheric interaction of the lithosphere and atmosphere. Deep degassing seems to be one of the main mechanisms of the anomalous behavior of atmospheric pressure during the implementation of strong events. It is most active in weakened zones. The mechanisms of the impact of deep degassing on the outer geospheres remain the subject of discussion.

CHANGES IN GEODYNAMIC SITUATION MANIFESTED IN SOIL RADON AND TEMPERATURE VARIATIONS AND ABNORMAL NATURAL PHENOMENA IN THE ZONE OF KATAV-IVANOVSK EARTHQUAKE (05.09.2018), THE SOUTHERN URALS

The strongest earthquake in the Urals registered during the period of instrumental observations, with a magnitude of ML-5.4 occurred in the area of Katav-Ivanovsk city, Chelyabinsk region, on 05.09.2018. In October 2018, Institute of Geophysics, the Ural Branch RAS organized temperature and radon observations. The conducted studies have shown that the behavior patterns of the volume radon activity (VRA) established for the tectonic event preparation in the subduction zone (Southern Kuriles), are also true for the South Ural region. The natural phenomena caused by the earthquake 2018 preparation are analyzed. During the observation period from 28.11.2018 to 23.05.2019, there was an increase in temperature with a gradient of 0.02°C per month. The observed patterns of VRA abnormal behavior before aftershocks in the Katav-Ivanovsk area are typical for the compression zone in the radon monitoring area. It is noted that the assumed compression deformations were manifested in the hydrogeodynamic field at least 10 years before the event proper. The proximity of earthquake foci to the identified aseismic zone within the boundaries of the East European Platform, the Pre-Ural Regional Trough, and the Bashkir anticlinorium indicates the most likely places of seismic events. The arranged temperature and radon monitoring network in the epicentral zone by observing aftershocks has shown the possibility of tracking the earthquake preparation process.

Three-dimensional density distribution and earthquake activity of the northern Lancangjiang fault in eastern Tibet

Due to the collision and lateral compression of the Indian-Asian plate, the Lancangjiang fault has become one of the most active strike-slip faults in the Qiangtang plate. The Qamdo 2013 Ms6.1 earthquake was induced from the northern section of the fault (the northern Lancangjiang fault). The destruction of the earthquake seriously endangers human activities and the construction of the Sichuan-Tibet Railway. However, there are few high-resolution geophysical data in this area, which limits the understanding of the deep structure, motion mode and seismic activity of the northern Lancangjiang active fault. In this paper, new gravity data were observed at a scale of 1: 200,000, covering an area of 1500km2. Based on wavelet multiscale decomposition, scratch analysis and 3-D inversion of gravity data methods, we obtained gravity anomalies of different scales, faults distribution and density structure. The results show that the overall crustal density change in Qamdo area is obvious and closely related to the distribution of faults. The Qamdo earthquake occurred at the layered interface with steep density change and the result from scratch analysis shows that the stress is concentrated at this position. We believe that the existence of stratigraphic density difference leads to different ability of strata to withstand regional tectonic stress, which is an important cause of the Qamdo earthquake. We analyzed the differences magnitude of earthquake activity between the northern Lancangjiang fault and Kamaduo-Gangtuo fault and believe that the northern Lancangjiang fault is more conducive to the preparation of large earthquakes. Otherwise, this paper provides geophysical evidence for the hypothesis that the northern Lancangjiang fault thrusts to the Qamdo Basin at a high angle.

Analysis of GNSS Data for Earthquake Precursor Studies Using IONOLAB-TEC in the Himalayan Region

Earthquake precursors are the indicators that appear before an earthquake. The release of radon gas, ionospheric disturbances, anomalous animal behavior, and so on are examples of seismic and aseismic events. Ionospheric perturbations can be proved to be a reliable method in earthquake prediction. The GNSS data detect changes in the ionosphere through the time lag of the transmitted GPS signals recorded at the Earth-based receivers. A negative TEC anomaly is caused by the stress released from the rocks before the earthquake, which elevates positive ions or p-holes in the atmosphere and decreases the ions in the ionosphere. A positive TEC anomaly follows this because of the increase in ions in the ionosphere. The ionospheric disruption in the Himalayan region is examined before five random earthquakes. For this, data from 15 separate GNSS stations are investigated using IONOLAB-TEC. A promising total electron content (TEC) data estimate with a temporal resolution of 30 s was analyzed. The results of the TEC data analysis depict the anomaly a month before the five earthquakes, followed by the later perturbation in the earthquake preparation zone. TEC anomalies are enhanced more by the uniform spatial distribution of GNSS stations in the epicentral region than by randomly distributed stations. The results of IONOLAB-TEC and the widely used GPS-TEC software were compared. Owing to its temporal resolution, IONOLAB-TEC has edge over the GPS-TEC software in that it can identify even the slightest negative anomalies before an earthquake.

Detection of fault zone head waves and the fault interface imaging in the Xianshuihe–Anninghe Fault zone (Eastern Tibetan Plateau)

SUMMARY Fault zone head waves (FZHWs) are an essential diagnostic signal that provides high-resolution imaging of fault interface properties at seismogenic depth. In this study, we validate the existence of a bi-material interface in the Xianshuihe–Anninghe Fault (XAF) zone around their intersection and determine the cross-fault velocity contrast. We employ a semi-automatic workflow to detect and pick FZHWs and direct P waves. In addition, to improve the identification ability of potential FZHWs in the automatic picking process, we adopt a ‘forward-detecting and backward-picking’ strategy combining the short-term average/long-term average (STA/LTA) algorithm with a kurtosis detector. The polarization and characteristic periods of the waveforms are then used to manually refine the picks and evaluate the quality. The results indicate that the average velocity contrast along the southern Xianshuihe Fault is 3–5 per cent, with the northeast side characterizing a faster P-wave velocity, in agreement with tomographic results. A systematic moveout between FZHWs and the direct P waves over a 100 km long fault segment reveals a single continuous interface in the seismogenic zone. The single bi-material fault structure might be conducive to the preparation of large earthquakes and further influences the corresponding dynamic rupture processes.

Geodynamics of source zones of strong earthquakes in Armenia

The purpose of the presented work is to determine and evaluate changes in the geodynamic characteristics of the strong earthquake source zone in the Javakheti highlands and central Armenia. The migration of source zones of strong earthquakes is given. A certain pattern has been revealed in the occurrence of destructive earthquakes in the territory of the Armenian Highlands. Active faults and fault zones of the territory of Armenia have been identified. The sources of strong earthquakes are studied according to seismicity data: seismogeodynamics of source zones and their relationship with the occurrence of strong earthquakes. The geodynamic conditions of source zones of strong earthquakes are estimated from the seismicity data of these zones in connection with the occurrence of strong tectonic movements and taking into account stress and strain fields. The periods of seismic calm, the features of changes in the level of groundwater and chemical composition in connection with the preparation of earthquakes are considered. Based on the block structure of the earth’s crust of the territory of Armenia, the dynamic parameters of the blocks of the earth’s crust (deformation, stress state) are determined. The geodynamics of strong earthquake source zones in the north and in the middle parts of Armenia, where an increase in seismic activity of these parts of the region has been observed in recent years, has been identified and studied. The seismic geodynamics is substantiated on the basis of data from the study of modern movements of the earth’s crust and in the historical past, which gives an idea of the dynamics of physical processes occurring in the source zones of earthquakes. A group of mineral water deposits, which is particularly sensitive to seismic events, has been identified. An estimate of the information content of the observational hydrogeodynamic network of Armenia is given. The geodynamic activity of the zone of sources of strong earthquakes in the Javakheti Highlands of the territory of Armenia has been revealed. A seismological section was built along the strike of rocks in order to determine the direction of migration of earthquake sources in the northern part of the region of Armenia.

Thermodynamic instability of the atmospheric boundary layer stimulated by tectonic and seismic activity

The number of researches during the recent two decades clearly demonstrated that a few weeks/days before moderate and strong earthquakes the specific thermal anomalies emerge within the earthquake preparation zones. In these papers some physical mechanisms were proposed, but they could not explain the avalanche character of the observed anomalies. In our works we studied a rich collection of pre-earthquake thermal/meteorological cases and proposed an explanation of the physical mechanism. We consider the Boundary Layer (BL) within the earthquake preparation zone as an open non-equilibrium system with energy dissipation. We show, that the external impact of ionization and following plasma chemical reactions between new-formed ions provide a specific autocatalytic exothermic reaction with a sharp increase of the thermal energy release. We use atmosphere chemical potential (ACP) as a parameter to estimate energy for processes connected with condensation. Monitoring of the latent heat release and ACP in the boundary layer can be used for the detection of tectonic and seismic activity and artificial phenomena, connected with air ionization. The statistical studies of strong M ≥ 6.5 global earthquakes demonstrated the high statistical confidence of ACP as the short-term earthquake precursor.

Integrated Analysis of Lithosphere-Atmosphere-Ionospheric Coupling Associated with the 2021 Mw 7.2 Haiti Earthquake

The search for Earthquake (EQ) precursors in the ionosphere and atmosphere from satellite data has provided significant information about the upcoming main shock. This study presents the abnormal atmospheric and ionospheric perturbations associated with the Mw 7.2 Haiti EQ on 14 August 2021 at geographical coordinates (18° N, 73° W) and shallow hypocentral depth of 10 km from the data of permanent Global Navigation Satellite System (GNSS) stations near the epicenter, followed by Swarm satellites data. The total vertical electron (VTEC) anomalies occur within a 5-day window before the main shock in the analysis of nearby operation stations, followed by Swarm (A and C satellites) ionospheric anomalies in the same 5-day window before the main shock. Moreover, the geomagnetic activities are completely quiet within 10 days before and 10 days after the main shock. Similarly, the atmospheric parameters endorse the EQ anomalies within 5 days before the main shock day. The evolution of gases from the lithosphere at the epicentral region possessed significant atmospheric and ionospheric perturbations within the EQ preparation period of 5-day before the main shock under the hypothesis of Lithosphere-Atmosphere-Ionosphere Coupling (LAIC).

Structure Earthquake Analysis Program using Computer-Aided IT Sensor

The purpose of this study is to develop a complex test and analysis technique to improve the reliability of seismic performance evaluation of buildings, and to establish a seismic performance evaluation system using shear damper as an earthquake preparation technology. In this study, validated examples of viscoelasticity provided by OpenSees were selected for verification of hybrid experimental results data and compared with hybrid experimental techniques. By applying the analysis program and the developed Labplugin, the hybrid experimental system built through the connection between the equipment was verified. As a result, the behavior of the cyclic loading test showed the general behavior of the damper, but in the hybrid test, the behavior of the damper with respect to the ground acceleration and the decrease in stiffness caused by fracture were found. From the above comparison experiment, it can be seen that the hybrid technique developed in this study shows excellent seismic behavior compared to the cyclic loading experiment, dynamic experiment, and analytical technique. With the system built in this study, it is judged that it is possible to design a structure damper in the future. In addition hybrid experimental system will help to conduct more economical and reliable research on seismic control by applying partial experimental data to structures with nonlinear behavior in the future.

Sound Range AE as a Tool for Diagnostics of Large Technical and Natural Objects.

Application of acoustic emission of the sound frequency range is under consideration. This range is of current interest for the diagnostics of the stability of mountain slopes, glaciers, ice covers, large technical constructions (bridges, dams, etc.) as well as for the detection of rock deformation anomalies preceding earthquakes. Acoustic sensors, which can be used to record and to determine the directivity of acoustic emission of the sound frequency range, are under consideration. The structure of the system for acoustic emission recording, processing and analysis is described. This system makes it possible to determine the direction to the acoustic emission source using one multi-component sensor. We also consider the algorithms for detection of acoustic emission pulses in a noisy background, and for the analysis of their structure using the Adaptive Matching Pursuit algorithm. A method for the detection of the direction to an acoustic emission signal source based on multi-component sensors is described. The results of application of sound range acoustic emission for the detection of the intensification of rock deformations, associated with earthquake preparation and development in the seismically active region of Kamchatka peninsula, are presented.

Seismicity-based 3D model of ruptured seismogenic faults in the North-South Seismic Belt, China

The North–South Seismic Belt produces the most frequent strong earthquakes in the Chinese continental region, such as the MS 8.0 Wenchuan earthquake on 12 May 2008 and Ms 7.0 Lushan earthquake on 20 April 2013. This seismicity results in significant hazards. Fault geometry modeling is crucial for analyzing earthquake preparation and trigger mechanisms, simulating and predicting strong earthquakes, inverting fault slip rates, etc. In this study, a novel method for obtaining geometric models of ruptured seismogenic faults over a large area is designed based on datasets from surface fault traces, fault orientations, focal mechanism solutions, and earthquake relocations. This method involves three steps. 1) An initial model of the fault geometry is constructed from the focal mechanism solution data. This initial model is used to select the earthquake relocation data related to the target fault. 2) Next, a fine model of the fault geometry with a higher resolution than that of the initial model is fitted based on the selected earthquake relocation data. 3) The minimum curvature interpolation method (Briggs, 2012) is adopted to build a 3D model of the subsurface fault geometry according to the three-dimensional coordinates of nodes on all profiles of each fault/segment. Based on this method and data collected in the North–South Seismic Belt, the fine morphologies of different faults along 1,573 transverse profiles were fitted, and a 3D model of 263 ruptured seismogenic faults or fault segments in the North–South Seismic Belt was built using the minimum curvature spatial interpolation method. Since the earthquake number decreases with increasing depth, the model uncertainty increases with increasing depth. Different ruptured faults have different degrees of seismicity, so different fault models may have different uncertainties. The overall fitting error of the model is 0.98 km with respect to the interpreted results, from six geophysical exploration profiles.

Variations of multiple gaseous emissions associated with the great Sumatra earthquakes in 2004 and 2005

Three-dimensional (3D) temporal variations and correlation analysis of CO, CH4 and O3 concentrations associated with the 26 December 2004 Sumatra-Andaman MW 9.1 Earthquake and 28 March 2005 Sumatra-Nias MW 8.6 Earthquake offshore of Sumatra, Indonesia were investigated using satellite data from AQUA AIRS in order to understand the lithospheric and atmospheric interactions during seismic activities. These great earthquakes occurred in the subduction zone northwest of the Sumatra Island. It was observed that large amounts of gases were emitted from the Earth's crust into the atmosphere before, during and after the earthquakes compared to the earthquake-free periods and background areas. Anomalies in CO, CH4 and O3 concentrations occurred along the NW-trending Sumatra fault system and peak values were found in the epicenter areas. Temporally, the anomalies occurred from 3 months before the Sumatra-Andaman Earthquake to 1 month after the Sumatra-Nias Earthquake and they lasted for 7 months. The correlation coefficients between the gas parameters increased with the period closer to the earthquake occurrence. More CO and CH4 were emitted from the epicenter area and O3 was produced in the background area during earthquake preparation period and occurrence reflected in the correlation analysis. The data indicated that the gaseous anomalies were most probably attributed to the gas emissions caused by the two great earthquakes that were accompanied by intense tectonic activities and fractures produced in the crust. After the underground gases were emitted into the atmosphere, they underwent a series of physical (diffusion, convection, etc.) and chemical reactions, which consequently lead to the gases (e.g. CO, CH4 and O3) anomalies at different altitudes in the atmosphere. The results are helpful in improving the judgment ability to understand geochemical earthquake anomalies and understanding the mechanism of lithosphere-coversphere-atmosphere-ionosphere coupling (LCAIC).

Применение изотопов радона для изучения вариаций напряженного состояния горных пород при прогнозе землетрясений

The results of interpretation of monitoring observations of radon-220 (thoron) and radon-222 monitoring observations, carried out in 2002-2004 on the Northern Tien-Shan, are presented. Prognostic capabilities of thoron as a short-term earthquakes precursor are shown. It is noted that the anomalies of thoron are more contrast in comparison with anomalies of radon-222. Insufficient contrast of radon-222 anomalies is explained by methodological in observations by seismic radon stations. The behavior of thoron during the earthquake preparation agrees with the previously established spatial-temporal patterns for radon-222 (Kozlova et al., 2021 Radon isotopes are most suitable for monitoring observations of the earthquake preparation process using gases that are part of the underground atmosphere. The prospect of using other gases is limited by the absence of their continuous generation, by the presence of a cumulative effect, and by the difficulty of registration. The above also applies to the use for prognostic purposes of variations in the content of chemical compounds dissolved in groundwater.

Измерение современных движений на станции «Талая» (юго-западная часть Байкальского рифта)

The rates of modern displacements are an important factor in the modern geodynamics of the Baikal rift system. Reflection of strong earthquakes in the experimental values of displacements is still to be discussed, as well as the question of modern vertical movements. According to the measurements of 1992–2022, performed by the methods of absolute gravimetry and space geodesy, the velocities of vertical and horizontal movements at the Talaya seismic station (Baikal Rift). The displacement rates were determined as 1.7 mm/year – 1.9 mm/year at the SEE relative to the Irkutsk point (Siberian platform). A set of methods was used to obtain the vertical velocity val-ues for different epochs, pre-, co- and post-period of Kultuk earthquake (2008, M = 6.3, 25 km to the epicenter). Subsidence rates vary from 1.1 mm/yr to 3.3 mm/yr. Possible signs of the preparation of Baikal earthquakes have been identified.

The problem of unaccompanied children in the earthquake; insufficient enrollment.

Türkiye experienced two of the most catastrophic earthquakes of the last century on February 6, 2023. The first earthquake with a magnitude of 7.7 occurred at 4.17 a.m. in Kahramanmaraş City. Nine hours later, the second earthquake with a magnitude of 7.6 hit a region, which has 10 cities and over 16 million people. After the earthquakes, the Director-General of the World Health Organization, Hans Kluge, announced that a level 3 emergency was declared.One of the problems that should be solved at the earliest period in earthquakes is the problem of orphans or unaccompanied children. These children, referred to as 'earthquake orphans', can be potential victims of violence, organized crime, organ trafficking, drug addiction, sexual exploitation, or human trafficking. The already low socioeconomic level of the region, the magnitude of the earthquake, and the turmoil in the emergency rescue organization cause concern about the fact that the number of fragile children's population that will be affected will be higher than expected. The problem of orphaned children experienced in previous major destructive earthquakes provides important experiences for earthquake preparation.

Проявления геомагнитной активности (солнечные вспышки и магнитные бури) в изменении электротеллурических потенциалов по данным измерений на Южно-Сахалинском геофизическом полигоне

The results of the analysis of changes in electrotelluric potentials (ETP) during the observation of intense solar flare events and intense magnetic storms on Sakhalin are presented. The data were studied in the period from July 20 to October 12, 2023. The absence of characteristic changes in the ETP (integral amplification or attenuation of noise in the low-frequency region) depending on the presence or absence of a solar flare event is shown. At the same time, in some cases, the strongest flashes were found to coincide with the appearance of signals of the GUV type (Geyser type ULF Variation). For almost three months of observations, five cases of quasi-periodic GUV series have been identified, four of which coincide completely or partially with the times of solar flares and magnetic storms. It should be noted that earlier in the literature, the appearance of these signals was not correlated with any physical process. At the same time, the identification of such patterns is an integral part of extensive work on identifying predictive signs of earthquake preparation in the ETP.

Modeling Locations with Enhanced Earth’s Crust Deformation during Earthquake Preparation near the Kamchatka Peninsula

In seismically active regions of the Earth, to which the Kamchatka peninsula refers, pre-seismic anomalies are recorded in different geophysical fields. One of such fields is the acoustic emission of rocks, the anomalies of which are recorded 1–3 days before earthquakes at the distance of the first hundreds of kilometers from their epicenters. Results of joint acoustic-deformation measurements showed that growth of geoacoustic radiation intensity occurs during the increase in the level of deformations in rock masses by more than one order compared to the background values. Simulation studies of the areas with increased deformation are realized to understand the causes of anomalous acoustic-deformation disturbance occurrences before strong earthquakes. The model is based on the assumption that the Earth’s crust in the first approximation can be considered as a homogeneous isotropic elastic half-space, and an earthquake source can be considered as a displacements along a rectangular fault plane. Based on these assumptions, deformation regions of Earth’s crust were modeled during the preparations of two earthquakes with local magnitudes ML≈5 occurred on the Kamchatka Peninsula in 2007 and 2009. The simulation results were compared for the first time with the data of a laser strainmeter-interferometer installed at the Karymshina observation site (52.83∘ N, 158.13∘ E). It was shown that, during the preparation of the both earthquakes, the Karymshina observation site was within the region of shear deformations ≈10−7, which exceeded the tidal ones by an order. On the whole, simulation results corresponded to the results of the natural observations. Construction of an adequate model for the generation of acoustic-deformation disturbances before strong earthquakes is topical for the development of an early notification system on the threat of catastrophic natural events.

Factors Associated with Knowledge of Evacuation Routes and Having an Emergency Backpack in Individuals Affected by a Major Earthquake in Piura, Peru.

Information on the prevention of earthquakes in Peru, a high-risk country, is still emerging. We determined the frequency and factors associated with knowledge of evacuation routes and the use of emergency backpacks in people affected by a major earthquake. A cross-sectional study using secondary data was conducted from August-December 2021 on people that experienced the 6.1 magnitude earthquake that occurred in Piura, Peru on 30 July 2021. The outcome was self-reported knowledge of evacuation routes and the use of emergency backpacks. The association with self-reported earthquake preparation training, use of sources of information on earthquakes, and sociodemographic variables was investigated. A total of 69.5% of participants knew evacuation routes, and 46.3% had an emergency backpack. A higher frequency of knowledge of evacuation routes was associated with previous training (PR: 1.47; 95% CI: 1.15-1.87), use of the media (PR: 1.35; 95% CI: 1.06-1.72), having received information from the COEN (PR: 1.19; 95% CI: 1.02-1.40), and with a greater number of household members (PR: 1.03; 95% CI: 1.01-1.06). There is a high frequency of knowledge of evacuation routes among participants. However, basic notions of prevention culture are still needed. This research contributes to policy development on earthquake preparation at the community level.