scholarly journals SEISMICITY of YAKUTIA in 2015

Author(s):  
S. Shibaev ◽  
B. Kozmin ◽  
A. Makarov

The results of monitoring the seismicity of the territory of Yakutia, based on observations of 23 digital seismic stations, are presented. A total of 607 earthquakes were recorded. A map of epicentres was compiled and their location was given in seismically active regions. The most active areas are Olekminsk in the south, Verkhoyansk and Chersky Ridge in the northeast and the Arctic part of the region. A significant decrease (19 times) in the amount of released seismic energy continued in comparison to its level in 2014. Instrumental and macroseismic data, focal mechanisms and seismotectonic connections are analyzed. The characteristics of the shaking South-Verkhoyansk earthquake occurring at the junction of the Verkhoyansk and Sette-Daban Ridges are considered.

Author(s):  
B. Kozmin ◽  
S. Shibaev

The results of Yakutia seismicity monitoring based on data from 24 digital seismic stations are presented. 718 earthquakes with KP=7–14 were recorded. A map of epicenters and their distribution by areas of the region are given. The most active areas were the Olekma and Aldan highlands in the south, the Laptev Sea, Chersky Range and Primorsky lowland in the north-east and the Arctic part of the region. A significant decrease (10-times less) in the amount of released seismic energy was observed in comparison with this parameter for 2013.


Author(s):  
B. Koz’min ◽  
Sergey Shibaev

. The paper presents the results of monitoring seismicity in Yakutia in 2013 based on the data from 24 digital seismic stations. A total of 5197 seismic events with Кp=6–15 are detected. A map of earthquake epicenters is compiled showing their distribution in different areas. Two major clusters of seismic events are recognized. The first one corresponds to the Arctic-Asian seismic belt (AASB) extending across the Laptev Sea shelf and the north eastern Asian continent towards the Sea of Okhotsk. The second Baikal–Stanovoy belt in the south of the region is traced from Lake Baikal through the Stanovoy Highlands and the Stanovoy Ridge to the Sea of Okhotsk. In South Yakutia, the Olekma–Stanovoy zone (OSZ), which makes the eastern part of the belt, is considered. Both belts form boundaries of major lithospheric plates. The first belt separates the Eurasian and North American plates, while the other divides the Eurasian plate from the Amurian one. The minimum seismic level is recorded within the OCZ, with no more than 0.04 % of the total seismic energy re-leased during 2013. The maximum seismicity is noted in the AASB with released energy making up 99.9 % of the total amount. That abrupt change in seismicity is due to the occurrence here of three strong earth-quakes, Ulakhan-Chistay, Ilin-Tas (Abyi), and Tas-Khayakhtakh with the intensities VII-IX in the epicenters (MS=4.9–6.9). The epicentral zone of the Tas-Khayakhtakh event (MS=4.9) that occurred on May, 2013 is considered in more detail. The motion in the source of this event indicate thrusting along the Dogdo fault. All the shakes took place within the Chersky Range, in the zone of influence of major faults of the Kolyma–Indigirka system (Ulakhan, Dogdo, Ilin–Tas) under conditions of NE compression (regime of interplate collision and transpression ). Seismotectonic relations, macroseismic data, and earthquake focal mechanism pa-rameters are discussed.


Author(s):  
T. Fokina ◽  
D. Safonov ◽  
D. Kostylev ◽  
V. Mikhaylov

The review of seismicity for Sakhalin in 2013 based on the data of four seismic stationary stations and 10 temporary digital seismic stations "DAT", working in the south of Sakhalin, is given. The main parameters of 688 earthquakes and focal mechanisms of five of them are determined. 42 earthquakes showed a macroseismic effect. The maps of the representativeness of earthquakes and of epicenters are given, the distribution of crust and deep earthquakes on the magnitude and their summarized energy for seven seismoactive districts are presented. For each area, seismic conditions are described. The seismicity of the Sakhalin region in 2013 can be characterized as moderate. Somewhat increased seismic activity was recorded in the East Sakhalin region, against the background seismicity in previous years. Somewhat increased activity was also recorded in the West Sakhalin region, where a moderately strong earthquake occurred with MLH=5.1.


Author(s):  
T. Fokina ◽  
D. Safonov ◽  
D. Kostylev ◽  
V. Mikhaylov

A review of the Amur and Primorye, Sakhalin, and the Kuril-Okhotsk region seismicity for 2015 is presented on the basis of data from the regional network of stationary seismic stations of the Sakhalin branch of the Geophysical Survey RAS with the involvement of data from adjacent seismological Russian and foreign agencies, as well as ten stations of the local network operating in the south Sakhalin. Parameters of 1643 seismic events have been determined, 126 of them are explosions. Focal mechanisms were calculated for 62 earthquakes. 48 earthquakes have shown a macroseismic effect. A map of the epicenters is presented, the distribution of the number N of crustal and deep-focus earthquakes by a magnitude, a total seismic energy ∑E for seismically active regions of three regions are given, in comparison with the average parameters N and ∑E for 20012014. For each region, an analysis of the parameters of the seismic regime in 2015 is given in comparison with long-term averages, the maximum and significant seismic events are described. The seismicity of the Priamurye and Primorye, Sakhalin, and the Kuril-Okhotsk region in 2015 can be characterized as a moderate one.


1981 ◽  
Vol 71 (3) ◽  
pp. 713-729 ◽  
Author(s):  
R. S. Crosson ◽  
E. T. Endo

abstract Initial focal mechanism determinations for the 29 November 1975 Kalapana, Hawaii, earthquake indicated discrepancy between the mechanism determined from teleseismic data by Ando and the mechanism determined using data from the local U.S. Geological Survey network surrounding the epicenter region. The resolution of this difference is crucial to correctly understand this earthquake, as well as to understand the tectonics of the south flank of Kilauea volcano. When a model with a low-velocity layer at the base of the crust is used for projection back to the focal sphere for the local network mechanisms, the discrepancy vanishes. To further investigate this result, focal mechanisms were determined using several contrasting models for a set of well-recorded earthquakes. A large number of these earthquakes have mechanisms identical to the main shock when the low-velocity layer model is used. Dispersion of P and T axes is also minimized by use of this model. A low-angle slip direction, favored for the main shock and typical of most other solutions, exhibits remarkable stability normal to the east rift zone of Kilauea. Our results suggest a tectonic model, similar in nature to that proposed by Ando, in which the south flank of Kilauea consists of a mobile block of crust which is relatively free to move laterally on a low-strength zone at about 10 km depth. Forceful injection of magma along the rift zones provides the loading stress which is released by catastrophic failure in the weak, horizontal layer in a cycle of perhaps 100 yr.


Author(s):  
Yuri Vinogradov ◽  
Mariya Ryzhikova ◽  
Natalia Petrov ◽  
Svetlana Poygina ◽  
Marina Kolomiets

The data on the seismicity of the Earth in the second half of 2020 at the level of strong earthquakes with magnitudes mb≥6.0 are given according to the data of the Alert Service of the Geophysical Survey RAS. The review also includes information on 54 tangible earthquakes in Russia and five earthquakes in adjacent territories that were felt in the settlements of the Russian Federation. Two of 67 strong earthquakes of the Earth with mb≥6.0 for the period under consideration were registered in the territory of Russia. For 15 strong earthquakes, the Alert Service published Information Messages within one or two days after their occurrence, for 14 earthquakes the information on focal mechanisms is provided. The strongest earthquake of the Earth with MS=7.9 occurred on July, 22 in the region of the Alaska Peninsula. The maximum human casualties and material damage during the study period were the result of the catastrophic intraplate earthquake with MS=6.8, which occurred on October, 30 in the Aegean Sea, near the Samos Island. As a result of the earthquake, 117 people died, 1054 were injured. The strongest earthquake on the territory of Russia was the deep-focus one with mb=6.4, which took place on November, 30 in the Tatar Strait, separating Sakhalin Island from continental Eurasia. The crustal Bystrinsk earthquake on September, 21 with MS=5.2, which occurred in the area of Lake Baikal, was felt with a maximum intensity I=6–7 on the territory of Russia. Comparative analysis of the rate of seismic energy released in the Globe in 2010-2020 showed that its value in the second half of 2020, as well as for 2019-2020 on average, is one of the lowest for the eleven-year period and indicates a seismic calm, which should be replaced by a period of intensification of global seismic and deformation processes


2018 ◽  
Vol 214 (2) ◽  
pp. 990-1003
Author(s):  
Raúl R Castro ◽  
Antonio Mendoza-Camberos ◽  
Arturo Pérez-Vertti

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