Regularities of Seismicity of Western and Central Uzbekistan (Southwestern Part of Western Tien-Shan Region)  

作　　者：Makhira T. Usmanova Abdusattor M. Sattarov Makhira T. Usmanova;Abdusattor M. Sattarov(Institute of Seismology Named after G. A. Mavlyanov of the Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan;Northeastern University, Boston, USA)

机构地区：[1]Institute of Seismology Named after G. A. Mavlyanov of the Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan [2]Northeastern University, Boston, USA

出　　处：《Open Journal of Earthquake Research》2021年第4期153-163,共11页地震研究（英文）

摘　　要：The paper discusses the spatial and temporal distribution of seismic activity in the southwestern part of the Western Tien Shan. The study identifies four groups of strong earthquakes that occurred in Western and Central Uzbekistan. The regularity of redistribution of the accumulated tectonic energy in the form of shuttle migration of seismicity with the recurrence rate of a group of strong earthquakes has been revealed. The synchronicity of periods of seismic activation of the Western Tien Shan (regional structure) and the Asian part of the Mediterranean-Asian seismic belt (structure of a large-regional scale) was found. At the same time, deviations from synchronicity are noted in the form of delays in the periods of seismic activation between the considered structures. The seismicity study revealed a deviation from the regularity of grouping of strong earthquakes in the seismic regime of the region. This was observed in the Gazli earthquakes. The strongest triple Gazli earthquakes of 1976 and 1984 with М = 7.0</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">7.3 were preceded by natural and technogenic triggers. Natural triggers included active fracturing (large fractures up to 100 km in length) in the north of Tamdybulak area, the absence any of tangible </span><span style="font-family:Verdana;">earthquakes in the epicentral area of Gazli for more than 40 years, and the appearance of small mud volcanoes</span></span><span style="font-family:Verdana;">—griffins before a strong earthquake. The technogenic triggers included a 40-year gas pumping at the Gazli fields and two underground nuclear explosions in 1966 (#273) and 1968 (#142) produced near the epicenter of the tectonic Gazli earthquakes of 1976 and 1984.The paper discusses the spatial and temporal distribution of seismic activity in the southwestern part of the Western Tien Shan. The study identifies four groups of strong earthquakes that occurred in Western and Central Uzbekistan. The regularity of redistribution of the accumulated tectonic energy in the form of shuttle migration of seismicity with the recurrence rate of a group of strong earthquakes has been revealed. The synchronicity of periods of seismic activation of the Western Tien Shan (regional structure) and the Asian part of the Mediterranean-Asian seismic belt (structure of a large-regional scale) was found. At the same time, deviations from synchronicity are noted in the form of delays in the periods of seismic activation between the considered structures. The seismicity study revealed a deviation from the regularity of grouping of strong earthquakes in the seismic regime of the region. This was observed in the Gazli earthquakes. The strongest triple Gazli earthquakes of 1976 and 1984 with М = 7.0</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">7.3 were preceded by natural and technogenic triggers. Natural triggers included active fracturing (large fractures up to 100 km in length) in the north of Tamdybulak area, the absence any of tangible </span><span style="font-family:Verdana;">earthquakes in the epicentral area of Gazli for more than 40 years, and the appearance of small mud volcanoes</span></span><span style="font-family:Verdana;">—griffins before a strong earthquake. The technogenic triggers included a 40-year gas pumping at the Gazli fields and two underground nuclear explosions in 1966 (#273) and 1968 (#142) produced near the epicenter of the tectonic Gazli earthquakes of 1976 and 1984.

关 键 词：Strong Earthquakes Shuttle Migration of Seismicity Cyclic Recurrence of Large Earthquakes Natural and Technogenic Triggers 

分 类 号：P31[天文地球—固体地球物理学]