Moment magnitudes of two large Turkish earthquakes on February 6,2023 from long-period coda

Two large earthquakes(an earthquake doublet)occurred in south-central Turkey on February 6,2023,causing massive damages and casualties.The magnitudes and the relative sizes of the two mainshocks are essential information for scientific research and public awareness.There are obvious discrepancies among the results that have been reported so far,which may be revised and updated later.Here we applied a novel and reliable long-period coda moment magnitude method to the two large earthquakes.The moment magnitudes(with one standard error)are 7.95±0.013 and 7.86±0.012,respectively,which are larger than all the previous reports.The first mainshock,which matches the largest recorded earthquakes in the Turkish history,is slightly larger than the second one by 0.11±0.035 in magnitude or by 0.04 to 0.18 at 95%confidence level.

Stochastic Approximate Solutions of Stochastic Differential Equations with Random Jump Magnitudes and Non-Lipschitz Coefficients

A class of stochastic differential equations with random jump magnitudes( SDEwRJMs) is investigated. Under nonLipschitz conditions,the convergence of semi-implicit Euler method for SDEwRJMs is studied. The main purpose is to prove that the semi-implicit Euler solutions converge to the true solutions in the mean-square sense. An example is given for illustration.

A Bayesian Approach to Seismic Hazard Estmation: Maximum Values of Magnitudes and Peak Ground Accelerations

A rather simple straightforward procedure of estimating maximum values of the considered parameter (earthquake magnitude in a given region or seismic peak ground acceleration at the considered site) and quantiles of its probabilistic distribution in a future time interval of a given length is presented. To assess the peak ground acceleration using this method, the input information is the earthquake catalog and the regressive relation where the peak seismic acceleration at a given point bears the magnitude and epicentral distance of the site considered (seismic attenuation law). The method is based on the Bayesian approach, in which the influence of uncertainties of magnitudes and seismic acceleration values can be taken into account. The main assumptions for the method are the Poissonian character of the seismic event flow, a frequency-magnitude law of Gutenberg-Richter’s type with a cutoff maximum value for the estimated parameter, and an earthquake catalog that has a rather large number of events. The method has been applied to seismic hazard estimation in California, the Balkans, and Japan.

Converting Tsunami Wave Heights to Earthquake Magnitudes

There is a fairly strict relation between maximum tsunami wave heights and causation earthquake magnitudes. This provides a new tool for estimating the magnitude of past earthquakes from the observed wave heights of related paleo-tsunami events. The method is subjected to a test versus two paleoseismic events with multiple independent estimates of corresponding earthquake magnitude. The agreement to the tsunami wave height conversion is good, confirming very high magnitudes of M 8.5 - 9.0 and M 8.4 - 8.5. Applying the same method to two Late Holocene events of methane venting tectonics indicates a ground shaking of forces equivalent to a M 8.0 earthquake, seriously changing previous long-term crustal hazard assessments.

Last Deglacial Soft-Sediment Deformation at Shawan on the Eastern Tibetan Plateau and Implications for Deformation Processes and Seismic Magnitudes

The eastern margin of the Tibetan Plateau is characterized by frequent earthquakes; however, research of paleo-earthquakes in the area has been limited^ owing to the alpine topography and strong erosion. Detailed investigations of soft-sediment deformation(SSD) structures are valuable for understanding the trigger mechanisms, deformation processes, and the magnitudes of earthquakes that generate such structures, and help us to understand tectonic activity in the region. To assess tectonic activity during the late Quaternary, we studied a well-exposed sequence of Shawan lacustrine sediments, 7.0 m thick, near Lake Diexi in the upper reaches of the Minjiang River. Deformation is recorded by both ductile structures(load casts, flame structures,pseudonodules, ball-and-pillow structures, and liquefied convolute structures) and brittle structures(liquefied breccia, and microfaults). Taking into account the geodynamic setting of the area and its known tectonic activity, these SSD structures can be interpreted in terms of seismic shocks. The types and forms of the structures,the maximum liquefaction distances, and the thicknesses of the horizons with SSD structures in the Shawan section indicate that they record six strong earthquakes of magnitude 6-7 and one with magnitude >7. A recent study showed that the Songpinggou fault is the seismogenic structure of the 1933 Ms7.5 Diexi earthquake. The Shawan section is located close to the junction of the Songpinggou and Minjiang faults, and records seven earthquakes with magnitudes of ?7. We infer,therefore, that the SSD structures in the Shawan section document deglacial activity along the Songpinggou fault.

Determination of the local magnitudes of small earthquakes using a dense seismic array in the Changning-Zhaotong Shale Gas Field,Southern Sichuan Basin

With the development of unconventional shale gas in the southern Sichuan Basin,seismicity in the region has increased significantly in recent years.Though the existing sparse regional seismic stations can capture most earthquakes with ML≥2.5,a great number of smaller earthquakes are often omitted due to limited detection capacity.With the advent of portable seismic nodes,many dense arrays for monitoring seismicity in the unconventional oil and gas fields have been deployed,and the magnitudes of those earthquakes are key to understand the local fault reactivation and seismic potentials.However,the current national standard for determining the local magnitudes was not specifically designed for monitoring stations in close proximity,utilizing a calibration function with a minimal resolution of 5 km in the epicentral distance.That is,the current national standard tends to overestimate the local magnitudes for stations within short epicentral distances,and can result in discrepancies for dense arrays.In this study,we propose a new local magnitude formula which corrects the overestimated magnitudes for shorter distances,yielding accurate event magnitudes for small earthquakes in the Changning-Zhaotong shale gas field in the southern Sichuan Basin,monitored by dense seismic arrays in close proximity.The formula is used to determine the local magnitudes of 7,500 events monitored by a two-phased dense array with several hundred 5 Hz 3 C nodes deployed from the end of February 2019 to early May 2019 in the Changning-Zhaotong shale gas field.The magnitude of completeness(MC)using the dense array is-0.1,compared to MC 1.1 by the sparser Chinese Seismic Network(CSN).In addition,using a machine learning detection and picking procedure,we successfully identify and process some 14,000 earthquakes from the continuous waveforms,a ten-fold increase over the catalog recorded by CSN for the same period,and the MC is further reduced to-0.3 from-0.1 compared to the catalog obtained via manual processing using the same dense array.The proposed local magnitude formula can be adopted for calculating accurate local magnitudes of future earthquakes using dense arrays in the shale gas fields of the Sichuan Basin.This will help to better characterize the local seismic risks and potentials.

Differences between magnitudes of Taiwan earthquakes from catalogs of Taiwan and Beijing

Taiwan is a region with very high seismicity where hundreds of earthquakes with ms occurred per year and more than 40 with m≥7 since 1900 due to it is located at the boundary of collision between Eurasian and the Philippine Sea plates.The magnitudes for the same event from these two catalogs of Taiwan and Beijing are different due to diferent data sources selected and different magnitude scales used. To measure sizes of Taiwan events in uniform magnitude scale, the author adopted a catalog of earthquakes with uniform local magnitude scale (Shin, 1993)compiled by Cheng (1996) in compiling a new catalog of Chinese earthquakes. To measure sizes of Taiwan events,we adopted uniform local magnitude scale for events with 5≤M<6. For event with M≥6 we still adopted IASPEI surface wave magnitude scale. Thus the statistic difference between two magnitude values from Taiwan and Beijing in magnitude interval 5≤M<6 reflects difference between Taiwan uniform local magnitode scale and Beijing surface wave magnitude scale. The statistic difference in magnitude interval he6 reflects difference between IASPEI surface wave magnitude scale and Beijing surface wave magnitude scale. Three data sources from "Wang","Cheng" and "Chinese mainland" of Taiwan events with m≥7 are given in this paper, in order to obtain a complete catalog.The statistic result indicates that Taiwan magnitude is slightly larger than Beijing magnitude for 998 events with 5≤M<6. The mean difference is about 0.13 of magnitude unit with deviation 0.32. Similarly, the mean difference is about 0.09 of magnitude unit with deviation 0.23 for 298 eventS with m≥6. We also noted that the difference of magnitude values between Beijing and Taiwan surface wave magnitUdes changed in different time period.Before 1971, most Taiwan magnitude values of the events is larger than Beijing’s. In contrast, most Beijing magnitude values of the events are larger than Taiwan magnitUde values aller 1972. It is probably related to data sources. Three catalogs of events with m≥7 are given in this paper Wang’s catalog (1995) includes 44 events with M≥7, Cheng’s (1996) 39 events and Chinese catalog, before 1911 compiled by Min (1995), 1912-1990 compiled by Wang, et al (1997) and 1991-1998 compiled by Yang, includes 41 events. The variety of these data sources discussed in this paper can be a useful reference for seismologists who use catalog seismic data do their research.However the statistic results and empirical relations presented in this paper can not be used for converting between magnitude scales, since some of them are not the original observation values. In addition, three catalogs of events with M≥ 7 given in this paper can be used for seismicity research comprehensively.

Comparison between different earthquake magnitudes determined by China Seismo-graph Network

By linear regression and orthogonal regression methods, comparisons are made between different magnitudes （local magnitude ML, surface wave magnitudes Ms and MsT, long-period body wave magnitude mB and short-period body wave magnitude mb） determined by Institute of Geophysics, China Earthquake Administration, on the basis of observation data collected by China Seismograph Network between 1983 and 2004. Empirical relations between different magnitudes have been obtained. The result shows that： ① As different magnitude scales reflect radiated energy by seismic waves within different periods, earthquake magnitudes can be described more objectively by using different scales for earthquakes of different magnitudes. When the epicentral distance is less than 1000 km, local magnitude ME can be a preferable scale; In case M〈4.5, there is little difference between the magnitude scales; In case 4.5〈M〈6.0, mB〉Ms, i.e., Ms underestimates magnitudes of such events, therefore, mB can be a better choice; In case M〉6.0, Ms〉mB〉mb, both mB and mb underestimate the magnitudes, so Ms is a preferable scale for determining magnitudes of such events （6.0〈M〈8.5）; In case M〉8.5, a saturation phenomenon appears in Ms, which cannot give an accurate reflection of the magnitudes of such large events; ② In China, when the epicentral distance is less than 1 000 km, there is almost no difference between ME and Ms, and thus there is no need to convert between the two magnitudes in practice; ③ Although Ms and Ms7 are both surface wave magnitudes, Ms is in general greater than Ms7 by 0.2～0.3 magnitude, because different instruments and calculation formulae are used; ④ mB is almost equal to mb for earthquakes around mB4.0, but mB is larger than mb for those of mB〉4.5, because the periods of seismic waves used for measuring mB and mb are different though the calculation formulae are the same.

Comparison between earthquake magnitudes determined by China seismograph network and US seismograph networks (I): Body wave magnitude

By using orthogonal regression method, a systematic comparison is made between body wave magnitudes determined by Institute of Geophysics of China Earthquake Administration (IGCEA) and National Earthquake Information Center of US Geological Survey (USGS/NEIC) on the basis of observation data from China and US seismograph networks between 1983 and 2004. The result of orthogonal regression shows no systematic error between body wave magnitude mb determined by IGCEA and mb (NEIC). Provided that mb (NEIC) is taken as the benchmark, body wave magnitude determined by IGCEA is greater by 0.2-0.1 than the magnitude determined by NEIC for M=3.5-4.5 earthquakes; for M=5.0-5.5 earthquakes, there is no difference; and for M greater than or equal 6.0 earthquakes, it is smaller by no more than 0.2. This is consistent with the result of comparison by IDC (International Data Center).

Some Statistical Aspects for Algerian Earthquake Catalogue

The scope of this study is to analyze some aspects of the Algerian earthquake catalogue between 1980 and 2009.Seismicity analysis is based on reliable compilation of earthquake catalogs obtained from different agencies.All intensities and magnitudes were converted to Ms magnitude using appropriate relationships.Dependent events were removed using adapted time and space windows.In addition,the completeness of the catalogue as a function of magnitude was determined from the standard deviation of occurrence rate plots,using the Stepp’s methodology.The remaining 2,016 independent earthquakes with Ms 2.2 were used to obtain various parameters(b-value,z-value)to characterize the temporal and spatial seismic activity for the entire northern part of Algeria.Finally,the obtained results are discussed to explain parameters variability.

Influence of complicated faults on the differentiation and accumulation of in-situ stress in deep rock mass

High geostress will become a normality in the deep because in-situ stress rises linearly with depth.The geological structure grows immensely intricate as depth increases.Faults,small fractures,and joint fissures are widely developed.The objective of this paper is to identify geostress anomalies at a variety of locations near faults and to demonstrate their accumulation mechanism.Hydrofracturing tests were conducted in seven deep boreholes.We conducted a test at a drilling depth of over one thousand meters to reveal and quantify the influence of faults on in-situ stresses at the hanging wall,footwall,between faults,end of faults,junction of faults,and far-field of faults.The effect of fault sites and characteristics on the direction and magnitude of stresses has been investigated and compared to test boreholes.The accumulation heterogeneity of stresses near faults was illustrated by a three-dimensional numerical simulation,which is utilized to explain the effect of faults on the accumulation and differentiation of in-situ stress.Due to regional tectonics and faulting,the magnitude,direction,and stress regime are all extremely different.The concentration degree of geostress and direction change will vary with the location of faults near faults,but the magnitude and direction of in-situ stress conform to regional tectonic stress at a distance from the faults.The focal mechanism solution has been verified using historical seismic ground motion vectors.The results demonstrate that the degree of stress differentiation varies according to the fault attribute and its position.Changes in stress differentiation and its ratio from strong to weak occur between faults,intersection,footwall,end of faults,and hanging wall;along with the sequence of orientation is the footwall,between faults,the end of faults,intersection,and hanging wall.This work sheds new light on the fault-induced stress accumulation and orientation shift mechanisms across the entire cycle.

Effect size in papers published by the Journal of Forestry Research:A missing treasure?

P values based on standard hypothesis testing are commonly reported in articles published by the Journal of Forestry Research(JFR).However,effect sizes are barely used and reported,even if they are of direct relevance to the primary questions of many of the published studies.The incorporation of effect sizes in studies published by JFR should be encouraged and promoted.Inclusion of effect sizes as a requirement in the journal guidelines will facilitate a major change in the way data are tested and interpreted,with the ultimate goal to exempt researchers from the custom of drawing conclusions merely based upon a dichotomous statistical result(P value).Such a policy can also lead to more informed decisions of whether identified effects are of practical relevance to the forestry.

Modified Cepstral Feature for Speech Anti-spoofing

The hidden danger of the automatic speaker verification(ASV)system is various spoofed speeches.These threats can be classified into two categories,namely logical access(LA)and physical access(PA).To improve identification capability of spoofed speech detection,this paper considers the research on features.Firstly,following the idea of modifying the constant-Q-based features,this work considered adding variance or mean to the constant-Q-based cepstral domain to obtain good performance.Secondly,linear frequency cepstral coefficients(LFCCs)performed comparably with constant-Q-based features.Finally,we proposed linear frequency variance-based cepstral coefficients(LVCCs)and linear frequency mean-based cepstral coefficients(LMCCs)for identification of speech spoofing.LVCCs and LMCCs could be attained by adding the frame variance or the mean to the log magnitude spectrum based on LFCC features.The proposed novel features were evaluated on ASVspoof 2019 datase.The experimental results show that compared with known hand-crafted features,LVCCs and LMCCs are more effective in resisting spoofed speech attack.

Real-time prediction of earthquake potential damage:A case study for the January 8,2022 M_(S) 6.9 Menyuan earthquake in Qinghai,China

It is critical to determine whether a site has potential damage in real-time after an earthquake occurs,which is a challenge in earthquake disaster reduction.Here,we propose a real-time Earthquake Potential Damage predictor(EPDor)based on predicting peak ground velocities(PGVs)of sites.The EPDor is composed of three parts:(1)predicting the magnitude of an earthquake and PGVs of triggered stations based on the machine learning prediction models;(2)predicting the PGVs at distant sites based on the empirical ground motion prediction equation;(3)generating the PGV map through predicting the PGV of each grid point based on an interpolation process of weighted average based on the predicted values in(1)and(2).We apply the EPDor to the 2022 M_(S) 6.9 Menyuan earthquake in Qinghai Province,China to predict its potential damage.Within the initial few seconds after the first station is triggered,the EPDor can determine directly whether there is potential damage for some sites to a certain degree.Hence,we infer that the EPDor has potential application for future earthquakes.Meanwhile,it also has potential in Chinese earthquake early warning system.

Results of Geomagnetic Studies on the Problem of Forecasting Strong Earthquakes in Uzbekistan

The article is devoted to the problem of forecasting strong earthquakes by the geomagnetic method. The geomagnetic method is widely used on this problem in seismically active regions of the world as one of the promising, informative and operational geophysical methods. The results of long-term geomagnetic studies on the problem of forecasting strong earthquakes in Uzbekistan are presented. Geomagnetic studies were carried out on the territories of the Tashkent, Ferghana, and Kyzylkum geodynamic polygons in the epicentral zones of strong earthquakes that occurred. Long-term, medium- and short-term precursors of earthquakes have been identified. Anomalous changes in the geomagnetic field associated with the decline in aftershock activity were also revealed. The dependence between the duration of the manifestation of long-term magnetic precursors and the magnitude of earthquakes is determined. Absolute proton magnetometers MMP-1, MV-01 (Russia), and G-856 (USA) were used to measure the geomagnetic field.

Design and Simulation of an Audio Signal Alerting and Automatic Control System

A large part of our daily lives is spent with audio information. Massive obstacles are frequently presented by the colossal amounts of acoustic information and the incredibly quick processing times. This results in the need for applications and methodologies that are capable of automatically analyzing these contents. These technologies can be applied in automatic contentanalysis and emergency response systems. Breaks in manual communication usually occur in emergencies leading to accidents and equipment damage. The audio signal does a good job by sending a signal underground, which warrants action from an emergency management team at the surface. This paper, therefore, seeks to design and simulate an audio signal alerting and automatic control system using Unity Pro XL to substitute manual communication of emergencies and manual control of equipment. Sound data were trained using the neural network technique of machine learning. The metrics used are Fast Fourier transform magnitude, zero crossing rate, root mean square, and percentage error. Sounds were detected with an error of approximately 17%;thus, the system can detect sounds with an accuracy of 83%. With more data training, the system can detect sounds with minimal or no error. The paper, therefore, has critical policy implications about communication, safety, and health for underground mine.

Earthquake Magnitude Probability and Gamma Distribution

The earthquake magnitude probability distribution is one of the underlying input data for certain earthquake analyses, such as probabilistic seismic hazard analysis. Nowadays, the method proposed by McGuire and Arabasz (1990) is commonly used for obtaining the (simulated) earthquake magnitude probability distributions. However, based on the observed earthquake data in 5 regions (Taiwan, Japan, California, Turkey, and Greece), the model did not fit the observation well. Instead, all of the case studies show that using the newly proposed gamma distribution can improve the simulation significantly compared to the conventional method.

The Hidden Earthquake Induced Liquefaction Risks in the Rohingya Refugee Camp Hills & Surrounding Areas of Ukhiya, Cox’s Bazar, Bangladesh—A Geotechnical Engineering Approach

Liquefaction is one of the major catastrophic geohazards which usually occurs in saturated or partially saturated sandy or silty soils during a seismic event. Evaluating the potential liquefaction risks of a seismically prone area can significantly reduce the loss of lives and damage to civil infrastructures. This research is mainly focused on the earthquake-induced liquefaction risk assessment based on Liquefaction Potential Index (LPI) values at different earthquake magnitudes (M = 5.0, 7.0 and 8.0) with a peak ground acceleration (amax) of 0.28 g in the Rohingya Refugee camp and surrounding areas of Ukhiya, Cox’s Bazar, Bangladesh. Standard Penetration Test (SPT) results have been evaluated for potential liquefaction assessment. The soils are mainly composed of very loose to loose sands with some silts and clays. Geotechnical properties of these very loose sandy soils are very much consistent with the criteria of liquefiable soil. It is established from the grain size analysis results;the soil of the study area is mainly sand dominated (SP) with some silty clay (SC) which consists of 93.68% to 99.48% sand, 0.06% to 4.71% gravel and 0% to 6.26% silt and clay. Some Clayey Sand (SC) is also present. The silty clay can be characterized as medium (CI) to high plasticity (CH) inorganic clay soil. LPI values have been calculated to identify risk zones and to prepare risk maps of the investigated area. Based on these obtained LPI values, four (4) susceptible liquefaction risk zones are identified as low, medium, high and very high. The established “Risk Maps” can be used for future geological engineering works as well as for sustainable planning, design and construction purposes relating to adaptation and mitigation of seismic hazards in the investigated area.

Stripe of normal mechanisms for crustal earthquakes with M ≤ 3.5 flanking the western side of the thrust front zone in the Andes backarc

Earthquakes with magnitudes M ≤ 3.5 were registered in the Andes backarc between ~32.5°S 33.75°S within a temporary experiment from November 2002 to March 2003. Data were collected from 15 seismological broad band stations, deployed above flat subduction section and also above the transitional to normal section of the Nazca plate. Seismic events were located mostly in part of the Southern Precordillera and Cerrilladas Pedemontanas of Mendoza Province. Focal mechanism solutions were obtained, for selected data between15 kmand35 kmdepths, from P wave first motion using FOCMEC software. A band trending NW-NNW of normal focal mechanism earthquakes is located just by the thrust front towards West, and covers the Southern tip of the Southern Precordillera and the Western side of the Cerrilladas Pedemontanas, Mendoza Province, Argentina. Thrust focal mechanism solutions obtained in the present work for events with magnitude less than or equal to 3.5 also show that the thrust front South of ~33.1°S is located in the same place as Mw ≥ 3.6 earthquakes. The most significant findings in this work are these signals of extensional regimen which appear in a compressional subduction tectonic regimen. Nevertheless the short temporal experiment precludes firm interpretations about this particular phenomenon. Probably it is related to a temporary stress relaxation. The normal earthquakes are likely associated to normal faults, and/or to their subsidiaries, that were inverted by contraction and now re-inverted at least transitorily as normal. These faults, which are near and to the East of the suture between Chilenia and Cuyania Paleozoic terranes, were originally involved in the Cuyo Triassic basin formation.

1988年日地大事件四次联测期间宇宙线强度变化(英文)

本文利用空间中心的NM—64—18型超中子堆和ACK—1型大游离室的资料,分析研究1988年四次联测宇宙线强度变化特性。 第四次联测(12月17日—25日)中,15日有个持续时间为2小时另8分的1B级耀斑,相应在17日有一个1.5％的宇宙线强度下降。12月16日有一个持续时间为3小时另4分的1B级耀班,引起18日的宇宙线强度下降达4％。两个都是1B级耀斑,且位置都在N26,引起的宇宙线强度下降相差这么大,是因为后者的持续时间比前大得多,且更靠近日面中心。这和以前的结果一致:即发生在日面中心区域的耀斑引起的宇宙线强度下降为最大。12月18日爆发的耀班尽管光学等级是3B,但它引起的宇宙线强度下降在20日仅达2.5％,远不如16日耀斑所引起的宇宙线强度下降效应。这是因为它的持续时间只有54分钟,且位置又在S31W40。以前已发现,耀斑有南北不对称和东西不对称性。上述18日的耀斑尽管它的光学等级是3B,但引起的宇宙线强度下降还是远小于16日的耀斑。17日和19日两个1B耀斑,也说明耀斑的南北不对称性,前一个位于S15W35,后一个在N24W27,经度相差不大,前者在南半球后者在北半球,所以后者使宇宙线有一个1.5％的下降,而前者几乎无影响。在其他三次联测中,只有两个1B级耀斑,且持续时间最多只有20分钟,所以看不出它们对宇宙线强度变化有任?