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1.
A new modified magnitude scale M
S
(20R) is elaborated. It permits us to extend the teleseismic magnitude scale M
S
(20) to the regional epicenter distances. The data set used in this study contains digital records at 12 seismic stations
of 392 earthquakes that occured in the northwest Pacific Ocean in the period of 1993–2008. The new scale is based on amplitudes
of surface waves of a narrow range of the periods (16–25 s) close to the period of 20 s, for distances of 80–3000 km. The
digital Butterworth filter is used for processing. On the basis of the found regional features concerning distance dependence
for seismic wave attenuation, all the stations of the region have been subdivided into two groups, namely, “continental” and
“island-arc.” For each group of stations, its own calibration function is proposed. Individual station corrections are used
to compensate for the local features. 相似文献
2.
A disastrous earthquake with a magnitude M
S
= 8.0 (M
W
= 7.9), in China called “the 5.12 Wenchuan earthquake,” occurred on May 12, 2008, in Sichuan province on the border between
the Sino-Tibetan Mountains and the Sichuan depression. The instrumental epicenter was registered in the southeastern part
of Wenchuan county, and the hypocenter depth was 14 km. As the strongest and most destructive earthquake within mainland China,
it caused numerous human losses and destruction of buildings and infrastructure. The seismic effect from the main shock and
aftershocks was felt in many counties, towns, and villages, though Sichuan province suffered the most. The maximum intensity
of the shocks was estimated at 11 degrees, according to the Chinese macroseismic scale. In the process of source opening,
from the southern part of Wenchuan county to the vicinities of Quingchuan, a seismic fault system with a total length up to
240 km out-cropped on the earth’s surface, confined to the Longmenshan fault belt. The seismic fault system disturbed the
original ground, resulting in the collapse or damage to various constructions, such as buildings, homes, bridges, roads, etc.
Fault offsets had a dextral strike-slip and thrust kinematic combination. The earthquake generated several tens of thousands
of landslides, rockfalls, and debris flows. Many dammed ponds appeared in the epicentral zone due to the activation of landslides.
Thus, the geological effects turned out to be the most destructive factor in this case. At the same time, the seismic intensity
of surface shaking was abnormally low even in direct proximity to the seismic fault system. Usually it was no more than 7–8
degrees. This macroseismic phenomenon may turn out to be rather typical for many major earthquakes. 相似文献
3.
Starting from the classical empirical magnitude-energy relationships, in this article, the derivation of the modern scales
for moment magnitude M
w and energy magnitude M
e is outlined and critically discussed. The formulas for M
w and M
e calculation are presented in a way that reveals, besides the contributions of the physically defined measurement parameters
seismic moment M
0 and radiated seismic energy E
S, the role of the constants in the classical Gutenberg–Richter magnitude–energy relationship. Further, it is shown that M
w and M
e are linked via the parameter Θ = log(E
S/M
0), and the formula for M
e can be written as M
e = M
w + (Θ + 4.7)/1.5. This relationship directly links M
e with M
w via their common scaling to classical magnitudes and, at the same time, highlights the reason why M
w and M
e can significantly differ. In fact, Θ is assumed to be constant when calculating M
w. However, variations over three to four orders of magnitude in stress drop Δσ (as well as related variations in rupture velocity V
R and seismic wave radiation efficiency η
R) are responsible for the large variability of actual Θ values of earthquakes. As a result, for the same earthquake, M
e may sometimes differ by more than one magnitude unit from M
w. Such a difference is highly relevant when assessing the actual damage potential associated with a given earthquake, because
it expresses rather different static and dynamic source properties. While M
w is most appropriate for estimating the earthquake size (i.e., the product of rupture area times average displacement) and
thus the potential tsunami hazard posed by strong and great earthquakes in marine environs, M
e is more suitable than M
w for assessing the potential hazard of damage due to strong ground shaking, i.e., the earthquake strength. Therefore, whenever
possible, these two magnitudes should be both independently determined and jointly considered. Usually, only M
w is taken as a unified magnitude in many seismological applications (ShakeMap, seismic hazard studies, etc.) since procedures
to calculate it are well developed and accepted to be stable with small uncertainty. For many reasons, procedures for E
S and M
e calculation are affected by a larger uncertainty and are currently not yet available for all global earthquakes. Thus, despite
the physical importance of E
S in characterizing the seismic source, the use of M
e has been limited so far to the detriment of quicker and more complete rough estimates of both earthquake size and strength
and their causal relationships. Further studies are needed to improve E
S estimations in order to allow M
e to be extensively used as an important complement to M
w in common seismological practice and its applications. 相似文献
4.
Zafeiria Roumelioti Anastasia Kiratzi Christoforos Benetatos 《Journal of Seismology》2010,14(2):309-337
We use 576 earthquakes of magnitude, M
w, 3.3 to 6.8 that occurred within the region 33° N–42.5° N, 19° E–30° E in the time period 1969 to 2007 to investigate the
stability of the relation between moment magnitude, M
w, and local magnitude, M
L, for earthquakes in Greece and the surrounding regions. We compare M
w to M
L as reported in the monthly bulletins of the National Observatory of Athens (NOA) and to M
L as reported in the bulletins of the Seismological Station of the Aristotle University of Thessaloniki. All earthquakes have
been analyzed through regional or teleseismic waveform inversion, to obtain M
w, and have measured maximum trace amplitudes on the Wood–Anderson seismograph in Athens, which has been in operation since
1964. We show that the Athens Wood–Anderson seismograph performance has changed through time, affecting the computed by NOA
M
L by at least 0.1 magnitude units. Specifically, since the beginning of 1996, its east–west component has been recording systematically
much larger amplitudes compared to the north–south component. From the comparison between M
w and M
L reported by Thessaloniki, we also show that the performance of the sensors has changed several times through time, affecting
the calculated M
L’s. We propose scaling relations to convert the M
L values reported from the two centers to M
w. The procedures followed here can be applied to other regions as well to examine the stability of magnitude calculations
through time. 相似文献
5.
Earthquake source parameters, seismological, geological, geophysical, geodetic, and macroseismic data are reported for the
source zone of the Tohoku earthquake (M = 9) that occurred on March 11, 2011 near the eastern coast of Honshu Island. The seismotectonic position of the seismic
source situated in the western Pacific active margin, distribution of epicenters and hypocenters of the main shock, foreshocks
and aftershocks, features of the focal mechanism solutions, and directions of the horizontal and vertical offsets of the Island
surface were studied to focus attention on the nature of deformation in the Honshu Region. The obtained data make it possible
to establish intraplate and interplate components in the complex source of the earthquake. Relationships between seismic and
geodetic manifestations were investigated. The Tohoku earthquake was suggested to be a great lithospheric structure. 相似文献
6.
The source parameters of the M
W
= 7.6 Olyutorskii earthquake were estimated using the moments of the slip rate function with degrees 1 and 2. The moments
were estimated from broadband P-wave records at 52 stations of the worldwide network. The first step was to find a function S(t) for each station; this function is an apparent source time function, i.e., the P-wave slip as radiated by the source toward a station under consideration. The method of empirical Green’s functions was used
to estimate S(t). The next step was to calculate the moments of S(t) of degrees 1 and 2 over time and to set up relevant equations to be solved by least squares for the unknown source moments.
The horizontal linear source was used as a nonparametric model for calculating the source moments. Haskell’s parametric model
was used for further interpretation of the source moments. The resulting estimates are as follows: the source centroid was
13–25 km southwest of the epicenter, the source was 105–120 km long, the source strike was 222°–228°, the rupture velocity
was 2.7–3.0 km/s, and the total radiation duration was 24–27 s. These estimates indicate a bilateral rupture dominated by
a southwestward sense of rupture propagation. The source characteristics are consistent with the aftershock area geometry
and with the focal mechanism, as well as with surface breakage as observed by geologists in the field. 相似文献
7.
We investigated the seismicity in the aftershock area of a great earthquake occurring on April 20, 2006 (21:04 LT) in the
area of the Koryak Autonomous Okrug. This analysis of the aftershock process was based on a complete catalog of the earthquakes
that were recorded during April–May 2006 by the regional network of seismic stations operated by the Kamchatka Branch of the
Geophysical Service of the Russian Academy of Sciences. We also made use of a catalog of low magnitude events for May 2–17
as recorded by a mobile seismic network deployed in the rupture zone. We provide a review of seismicity for the Koryak Upland
for the period of instrumental observations in the 20th and early 21st centuries. 相似文献
8.
The seismic waves excited by the M
w
7.6 Olyutorskii earthquake that occurred on April 20, 2006 in the Koryak Upland gave rise to water-level changes in five
wells situated in continental areas of Kamchatka at hypocentral distances of 750–1150 km. We describe the effects due to seismic
waves, as well as the water-level anomalies for February–April 2006 before the earthquake. We used an original technique for
the processing of water-level records based on the study of barometric and tidal water-level responses in order to estimate
the volume strain in water-saturated rocks during synchronous level variations at two wells. We discuss possible mechanisms
for producing anomalous water-level changes due to elastic deformation of monitored groundwater reservoirs and to crack dilatancy
in the water-saturated rocks. 相似文献
9.
Prantik Mandal R K Chadha C Satyamurty I P Raju N Kumar 《Pure and Applied Geophysics》2005,162(12):2479-2504
Site response in the aftershock zone of 2001 Bhuj Mw 7.7 earthquake has been studied using the H/V spectral ratio method using 454 aftershocks (Mw 2.5–4.7) recorded at twelve three-component digital strong motion and eight three-component digital seismograph sites. The
mean amplification factor obtained for soft sediment sites (Quaternary/Tertiary) varies from 0.75–6.03 times for 1–3 Hz and
0.49–3.27 times for 3–10 Hz. The mean amplification factors obtained for hard sediment sites (hard Jurassic/Mesozoic sediments)
range from 0.32–3.24 times for 1–3 Hz and 0.37–2.18 times for 310 Hz. The upper bounds of the larger mean amplification factors
for 1–3 Hz are found to be of the order of 3.13–6.03 at Chopadwa, Vadawa, Kavada, Vondh, Adhoi, Jahwarnagar and Gadhada, whereas,
the upper bounds of the higher mean amplification factors at 3–10 Hz are estimated to be of the order of 2.00–3.27° at Tapar,
Chopadwa, Adhoi, Jahwarnagar, Gandhidham and Khingarpur. The site response estimated at Bhuj suggests a typical hard-rock
site behavior. Preliminary site response maps for 1–3 Hz and 310 Hz frequency ranges have been prepared for the area extending
from 23–23.85 °N and 69.65–70.85°E. These frequency ranges are considered on the basis of the fact that the natural frequencies
of multi-story buildings (3 to 10 floor) range between 1–3 Hz, while the natural frequencies for 1 to 3 story buildings vary
from 3–10 Hz. The 1–3 Hz map delineates two distinct zones of maximum site amplification (>3 times): one lying in the NW quadrant
of the study area covering Jahwarnagar, Kavada and Gadadha and the other in the SE quadrant of the study area with a peak
of 6.03 at Chopadwa covering an area of 70 km × 50 km. While the 3–10 Hz map shows more than 2 times site amplification value
over the entire study area except, NE quadrant, two patches in the southwest corner covering Bhuj and Anjar, and one patch
at the center covering Vondh, Manfara and Sikara. The zones for large site amplification values (∼3 times) are found at Tapar,
Chopadwa, Adhoi and Chobari. The estimated site response values show a good correlation with the distribution of geological
formations as well as observed ground deformation in the epicentral zone. 相似文献
10.
Sliding-window cross-correlation method is firstly adopted to identify sPn phase, and to constrain focal depth from regional
seismograms, by measuring the time separation between sPn and Pn phases. We present the focal depths of the 17 moderate-sized
aftershocks (M
S⩾5.0) of the Wenchuan M
S8.0 earthquake, using the data recorded by the regional seismic broadband networks of Shaanxi, Qinghai, Gansu, Yunnan and
Sichuan. Our results show focal depths of aftershocks range from 8 to 20 km, and tend to cluster at two average depths, separate
at 32.5°N, i.e., 11 km to the south and 17 km to the north, indicating that these aftershocks are origin of upper-to-middle
crust. Combined with other results, we suggest that the Longmenshan fault is not a through-going crustal fault and the Pingwu-Qingchuan
fault may be not the northward extension of the Longmenshan thrust fault.
Supported by the National Natural Science Foundation of China (Grant Nos. 40604009 and 40574040) and Special Project for the
Fundamental R & D of Institute of Geophysics, China Earthquake Administration (Grant No.DQJB08B20) 相似文献
11.
Earthquake surface rupture is the result of transformation from crustal elastic strain accumulation to permanent tectonic
deformation. The surface rupture zone produced by the 2001 Kunlunshan earthquake (M
w
7.8) on the Kusaihu segment of the Kunlun fault extends over 426 km. It consists of three relatively independent surface rupture
sections: the western strike-slip section, the middle transtensional section and the eastern strike-slip section. Hence this
implies that the Kunlunshan earthquake is composed of three earthquake rupturing events, i.e. the M
w
=6.8, M
w
=6.2 and M
w
⩽=7.8 events, respectively. The M
w
=7.8 earthquake, along the eastern section, is the main shock of the Kunlunshan earthquake, further decomposed into four rupturing
subevents. Field measurements indicate that the width of a single surface break on different sections ranges from several
meters to 15 m, with a maximum value of less than 30 m. The width of the surface rupture zone that consists of en echelon
breaks depends on its geometric structures, especially the stepover width of the secondary surface rupture zones in en echelon,
displaying a basic feature of deformation localization. Consistency between the Quaternary geologic slip rate, the GPS-monitored
strain rate and the localization of the surface ruptures of the 2001 Kunlunshan earthquake may indicate that the tectonic
deformation between the Bayan Har block and Qilian-Qaidam block in the northern Tibetan Plateau is characterized by strike-slip
faulting along the limited width of the Kunlun fault, while the blocks themselves on both sides of the Kunlun fault are characterized
by block motion. The localization of earthquake surface rupture zone is of great significance to determine the width of the
fault-surface-rupture hazard zone, along which direct destruction will be caused by co-seismic surface rupturing along a strike-slip
fault, that should be considered before the major engineering project, residental buildings and life line construction.
Supported by the National Natural Science Foundation of China (Grant No. 40474037) and the National Basic Research Program
of China (Grant No. 2004CB418401) 相似文献
12.
In this paper the crustal velocity structure are imaged at the annual scale for determining the evolution of 3D velocity structure before the Dayao earthquakes in 2003, and the relation between physical variation of medium and cause of earthquake occurrence is discussed. Checkerboard resolution tests show that the spatial resolution at 15 km depth is approximate 0.6 around Dayao. Error analyses show that the error (Approximate 0.02 km/s) at the focus area is far smaller than the magnitude (approximate 0.15 km/s) of velocity variation. Results of the studies show that a NNW-striking juncture zone of high-and low-velocity is formed before Dayao earthquake, whose strike is basically consistent with that of aftershock distribution of Dayao earthquakes and the focal mechanism, and the hypocenters lie on the high-velocity side of juncture zone. Furthermore, there is a low-velocity body under the hypocenters after Dayao earthquakes. The evolution of velocity structure provides restriction for discussing the circumstances of earthquake gestating and occurring. 相似文献
13.
We have measured group delays of the spectral components of high-frequency P-waves along two portions of the North Anatolian Fault Zone (NAFZ) in Turkey and in a region of southern Germany. Assuming that the observed dispersion is associated with attenuation in the crust and that it can be described by a continuous relaxation model, we obtained Q and the high-frequency relaxation times for those waves for each of the three regions. Individual P-wave Q values exhibit large scatter, but mean values in the NAFZ increase from about 25 to 60 over the distance range 5–90 km. Mean Q values are somewhat higher in the eastern portion of the NAFZ than in the western portion for measurements made at distances between 10 and 30 km. P-wave Q values in Germany range between about 50 and 300 over the hypocentral distance range 20–130 km. In that region we separated the effects of Q for basement rock (2–10 km depth) from that of the overlying sediment (0–2 km depth) using a least-squares method. Q varies between 100 and 500 in the upper 8–10 km of basement, with mean values for most of the distance range being about 250. Q in the overlying sediments ranges between 6 and 10. Because of large scatter in the Q determinations we investigated possible effects that variations of the source-time function of the earthquakes and truncation of the waveform may have on Q determinations. All of our studies indicate that measurement errors are relatively large and suggest that useful application of the method requires many observations, and that the method will be most useful in regions where the number of oscillations following the initial P pulse is minimized. Even though there is large scatter in our Q determinations, the mean values that we obtained in Turkey are consistent with those found in earlier studies. Our conclusions that Q is significantly higher in the basement rock of Germany than in the basement rock of Turkey and that Q is lower in western Turkey than in eastern Turkey are also consistent with results of Q studies using Lg coda. 相似文献
14.
V. V. Mordvinova A. Deschamps T. Dugarmaa J. Deverchére M. Ulziibat V. A. Sankov A. A. Artem’ev J. Perrot 《Izvestiya Physics of the Solid Earth》2007,43(2):119-129
The S wave velocity distribution in the Earth’s crust and the first two hundred kilometers of the upper mantle is inferred from data of a seismological linear network including 18 broadband stations installed in the framework of the international teleseismic experiment carried out in 2003 in the south of Siberia and in Mongolia. Models were constructed by using P-to-S received function inversion beneath each station. Vertical cross sections of S wave velocities from the surface to depths of 65 and 270 km covering the entire 1000-km profile are constructed by the linear spline interpolation of individual velocity models. The vertical sections are also represented as anomalies relative to the standard velocity model. The most intense low velocity anomalies (from ?3 to ?6%) in the crust and upper mantle are identified beneath the Sayan, Khamar-Daban, and Khangai highlands and the Djida fold zone and agree both with other geophysical data and with the distribution of Late Cenozoic volcanic fields. The results of this work suggest that the activation of Mongolian-Siberian highlands is largely connected with uplift of the asthenosphere to the base of the crust. 相似文献
15.
The characteristics of dayside auroras during the large (16–24 nT) positive values of the IMF B
z
component, observed on January 14, 1988, during the interaction between the Earth’s magnetosphere and the body of the interplanetary
magnetic cloud, have been studied based on the optical observations on Heiss Island. A wide band of diffuse red luminosity
with an intensity of 1–2 kilorayleigh (kR) was observed during 6 h in the interval 1030–1630 MLT at latitudes higher than
75° CGL. Rayed auroral arcs, the brightness of which in the 557.7 nm emission sharply increased to 3–7 kR in the postnoon
sector immediately after the polarity reversal of the IMF B
y
component from positive to negative, were continuously registered within the band. Bright auroral arcs were observed at the
equatorward edge of red luminosity. It has been found out that the red auroral intensity increases and the band equatorward
boundary shifts to lower latitudes with increasing solar wind dynamic pressure. However, a direct proportional dependence
of the variations in the auroral features on the dynamic pressure variations has not been found. It has been concluded that
the source of bright discrete auroras is located in the region of the low-latitude boundary layer (LLBL) on closed geomagnetic
field lines. The estimated LLBL thickness is ∼3 R
e
. It has been concluded that the intensity of the dayside red band depends on the solar wind plasma density, whereas the position
of the position equatorward boundary depends on the dynamic pressure value and its variations. 相似文献
16.
The work presents statistical methods for estimating the distribution parameters of rare, strong earthquakes. Using the two
main theorems of extreme value theory (EVT), the distribution of T-maximum (the maximum magnitude over the time period T). Two methods for estimating the parameters of this distribution are proposed using the Generalized Pareto Distribution (GPD)
and the General Extreme Value Distribution (GEV). In addition, the that allow the determination of the distribution of the
T-maximum for an arbitrary value of T are proposed. The approach being used clarifies the nature of the instability of the widely accepted M max parameter. In the work, instead of unstable values of the M max parameter, the robust parameter Q
T
(q), the q level quantile for the distribution of the T-maximum, is proposed to be used. The described method has been applied to the Harvard Catalogue of Seismic Moments of 1977–2006
and to the Magnitude Catalogue for Fennoscandia in 1900–2005. Moreover, the estimates of parameters of the corresponding GPD
and GEV distributions, in particular, the most interesting shape parameter and the values of the M
max and Q
T
(q) parameters are given. 相似文献
17.
Seismic tomography is a viable tool in building depth-velocity models in the presence of strong lateral velocity variations. In this study 3-D P- and S-velocity models for the crust of southern California are constrained using more than 1,000,000 P-wave first arrivals and 130,000 S-wave arrivals from local earthquakes. To cope with the uneven distribution of raypaths, a multi-scale tomography is applied with overlapping model cells of different sizes. Within the 300 × 480 × 39 km3 model volume, the smallest cell size is 10 × 10 × 3 km3. During the iterations of velocity updating, earthquake hypocenters are determined using both P and S arrivals, and full 3-D ray tracing is implemented. Except near the edges and in the lower crust, the resultant models are robust according to various tests on the effects of reference models, resolution and signal-to-noise ratio. The tomographic velocities at shallow depths correlate very well with the regional geology of southern California. In the upper crust the P-wave and S-wave models exhibit slow velocities in major sedimentary basins and fast velocities in areas of crystalline rocks. Mid-crustal low velocity zones are present under the Coso Range, San Gabriel Mountains, and a large portion of the Mojave Desert. P- and S-velocity patterns maintain their similarity in the lower crust though the models are less reliable there. 相似文献
18.
The optical observations on Heiss Island (Φ′ = 75.0°) have been used to study the characteristics of auroras in the near-noon
MLT sector after abrupt increases in the solar wind dynamic pressure at negative and positive polarity of the IMF B
z
component. It has been found out that the 427.8 and 557.7 nm emission intensities considerably increased at B
z
< 0 both equatorward of the dayside red luminosity band and within this band. The value of the emission intensities at a
red luminosity maximum (I
6300/I
5577 ∼ 0.5) indicates that energetic electron precipitation is of the magnetospheric origin. At B
z
> 0, fluxes of harder (E > 1 keV) precipitating electrons were superimposed on the soft spectrum of precipitating particles in the equatorial part
of the red luminosity band. This red band part was hypothetically caused by the low-latitude boundary layer (LLBL) on closed
lines of the geomagnetic field, the estimated thickness of which is ∼3 R
e
. The 557.7 nm emission intensity increased during 3–5 min after SC/SI and was accompanied by the displacement of the red
band equatorward boundary toward lower latitudes. The displacement value was ∼150–200 km when the dynamic pressure abruptly
increased by a factor of 3–5. After SC/SI, the 630.0 nm emission intensity continued increasing during 16–18 min. It is assumed
that the time of an increase in the red line intensity corresponds to the time of saturation of the magnetospheric boundary
layers with magnetosheath particles after an abrupt increase in their density. 相似文献
19.
Teleseismic P-wave receiver functions at 20 broadband seismic stations in the Longmenshan fault zone (LMFZ) and its vicinity
were extracted, and the crustal thickness and the P- and S-wave velocity ratio were calculated by use of the H-k stacking algorithm. With the results as constraints, the S-wave velocity structures beneath each station were determined
by the inversion of receiver functions. The crustal structure of the Rear-range zone is similar to that of the Songpan-Garze
Block, whereas the velocity structure of the Fore-range zone resembles that of Sichuan Basin, implying that the Central Principal
Fault of LMFZ is the boundary between the eastern Tibetan Plateau and the Yangtze Block. Lower velocity zone exists in lower
crust of the Songpan-Garze Block and the central-southern segment of the Rear-range zone, which facilitates the detachment
of the material in upper and middle crust. Joint analysis of the receiver functions and the Bouguer gravity anomalies supports
the thesis on the detachment-thrust mode of the LMFZ. A double-detachment pattern is suggested to the tectonic setting in
the Songpan-Garze Block. The upper detachment occurs at the depth of 10-15 km, and represents a high-temperature ductile shear
zone. There is a lower detachment at the depth of about 30 km, below which the lower crust flow exists in the eastern Tibetan
Plateau. Interpretation of the Bouguer gravity anomalies indicates that the Sichuan Basin is of higher density in upper and
middle crust in comparison with that of the Songpan-Garze Block. The LMFZ with higher density is the result from the thrusting
of the Songpan-Garze Block over the Sichuan Basin. In the lower crust, higher P velocity and higher density in the Sichuan
Basin are related to more rigid material, while lower S velocity and lower density in the Songpan-Garze Block are related
to the softened and weakened material. The higher density block beneath the Sichuan Basin obstructs the eastward flow of lower
crustal material from the Tibetan Plateau, which is driven by the compression of northward movement of Indian Plate. The eastward
movement of upper and middle crustal material is also obstructed by the rigid Yangtze Block, resulting in the stress concentrated
and accumulated along the LMFZ. When the stress releases sharply, the Wenchuan M
s8.0 earthquake occurs.
Supported by the National Natural Science Foundation of China (Grant Nos. 40334041, 40774037) and Joint Foundation of Earthquake
Science (Grant No. 1040062) 相似文献
20.
Ya. B. Radziminovich A. I. Seredkina V. I. Melnikova N. A. Gilyova 《Seismic Instruments》2017,53(4):323-332
The paper considers the Argun earthquake of July 22, 2011 (M w = 4.5), which occurred in the Argun River valley in a low-seismicity territory in China. The focal parameters of the earthquake (depth of the hypocenter, moment magnitude, scalar seismic moment, and focal mechanism) were determined by calculating the seismic moment tensor from the amplitude spectra of surface waves and the data on the signs of the first arrivals of body waves at regional stations. The solution of the focal mechanism makes it possible to assume a relationship between the earthquake focus and a fault with a northeastern strike bordering the southeastern side of the Argun Basin (in Chinese territory). The Argun earthquake was felt in Russia with an intensity of II–III to V at the epicentral distances up to 255 km. The intensity of shaking did not exceed values suggested by new GSZ-2012 and GSZ-2014 seismic zoning maps of Russian territory. Nevertheless, the question on the possible occurrence of stronger earthquakes in the studied region remains open. 相似文献