We employed a double-difference algorithm （hypoDD） to relocate earthquakes within the region bounded by 66°E-78°E and 32°N-42°N in the period of 1964-2003 reported by the International Seismologi...We employed a double-difference algorithm （hypoDD） to relocate earthquakes within the region bounded by 66°E-78°E and 32°N-42°N in the period of 1964-2003 reported by the International Seismological Center （ISC）. The improved hypocentral locations delineate a double-layered Wadati-Benioff zone in the eastern Hindu Kush intermediate seismic belt. Based on this feature and other evidences, we propose that the intermediate-depth earthquakes beneath the Pamir-Hindu Kush region may occur in two collided subduction zones with opposite dip directions.展开更多
According to the feature of Hindukush-Pamirs intermediate focus earthquake belt with a S-shaped pattern of dip direction reversion by using the data of earthquake catalogues obtained by seismic networks in Xinjiang an...According to the feature of Hindukush-Pamirs intermediate focus earthquake belt with a S-shaped pattern of dip direction reversion by using the data of earthquake catalogues obtained by seismic networks in Xinjiang and Mid-Asia area of the former Soviet Union, by means of focal mechanism solution and tectonic stress analysis, it is considered that the intermediate focus earthquake belt is possibly formed by the compression rupture which is caused by the collision between Indian and European Plates in the lithosphere of the upper mantle. Under the action of torsion moment, the continuous torsional break of reverse part of the earthquake belt might be the reason why the intermediate focus strong earthquakes occur repeatedly in the same place. In this paper, the boundary line between the intermediate focus earthquake belt and the shallow focus earthquake region of the western part of south Tianshan is also defined from the angle of seismicity division.展开更多
The tempo-spatial variation of seismic activity before great Chile Mw8.8 earthquake on February 27, 2010 is studied. Some results are as follows： ①Two types of seismic gaps appeared before the Chile MwS.8 shock. One...The tempo-spatial variation of seismic activity before great Chile Mw8.8 earthquake on February 27, 2010 is studied. Some results are as follows： ①Two types of seismic gaps appeared before the Chile MwS.8 shock. One is background gap of Mw≥8.0 earthquakes with 360 km length since 1900, the other is seismogenic gap formed by M≥5.5 earth- quakes with 780km length five years before the Chile earthquake; ②There was only one Mw7.1 earthquake in the middle and southern part of Chile from 1986 to 2010. The obvious quiescence of Mw≥7.0 earthquake is the long-term background anomaly for the Chile earthquake; ③ The quiescence of M≥6.5 earthquakes appeared in South American block and its vicinity during the period from 2007 to 2009, and the quietude state has been disappeared three months before the Chile Mw8.8 earthquake; ④ The deep and intermediate-depth earthquake activity has been noticeablely strengthened in the subduction zone of South American block since 1993; ⑤The great Chile earthquake shows that global seismicity is still in the active period of Mw≥8.5 earthquakes since 2004. Based on the characteristics of the former two active periods, several great earthquakes with Mw≥8.5 would take place in a few years. In addition, the circum-Pacific seismic belt would be the main region for Mw≥8.0 earthquakes.展开更多
This paper offers a positive research result of TIP before 16 strong earthquakes in North and Southwest China and their nearby areas since 1979 by using improved algorithm M8.The result showed that 14 of them were det...This paper offers a positive research result of TIP before 16 strong earthquakes in North and Southwest China and their nearby areas since 1979 by using improved algorithm M8.The result showed that 14 of them were determined to occur within the times of increased probability.TIP precaution occupies about 37% of the total space-time domain.That means we have made quite good results of intermediate-term prediction of strong earthquakes.So the method could be used as one of the useful means of the intermediate-term prediction of strong earthquakes.展开更多
基金partly sup-ported by the National Fundamental Science Program of China under(No.2004cb418406)the National Natural Science Foundation of China(No.90814002)Key Projects in the National Science & Technology PillarProgram during the Eleventh Five-year Plan Period(No.2008BAC38B02-4)
文摘We employed a double-difference algorithm （hypoDD） to relocate earthquakes within the region bounded by 66°E-78°E and 32°N-42°N in the period of 1964-2003 reported by the International Seismological Center （ISC）. The improved hypocentral locations delineate a double-layered Wadati-Benioff zone in the eastern Hindu Kush intermediate seismic belt. Based on this feature and other evidences, we propose that the intermediate-depth earthquakes beneath the Pamir-Hindu Kush region may occur in two collided subduction zones with opposite dip directions.
文摘According to the feature of Hindukush-Pamirs intermediate focus earthquake belt with a S-shaped pattern of dip direction reversion by using the data of earthquake catalogues obtained by seismic networks in Xinjiang and Mid-Asia area of the former Soviet Union, by means of focal mechanism solution and tectonic stress analysis, it is considered that the intermediate focus earthquake belt is possibly formed by the compression rupture which is caused by the collision between Indian and European Plates in the lithosphere of the upper mantle. Under the action of torsion moment, the continuous torsional break of reverse part of the earthquake belt might be the reason why the intermediate focus strong earthquakes occur repeatedly in the same place. In this paper, the boundary line between the intermediate focus earthquake belt and the shallow focus earthquake region of the western part of south Tianshan is also defined from the angle of seismicity division.
文摘The tempo-spatial variation of seismic activity before great Chile Mw8.8 earthquake on February 27, 2010 is studied. Some results are as follows： ①Two types of seismic gaps appeared before the Chile MwS.8 shock. One is background gap of Mw≥8.0 earthquakes with 360 km length since 1900, the other is seismogenic gap formed by M≥5.5 earth- quakes with 780km length five years before the Chile earthquake; ②There was only one Mw7.1 earthquake in the middle and southern part of Chile from 1986 to 2010. The obvious quiescence of Mw≥7.0 earthquake is the long-term background anomaly for the Chile earthquake; ③ The quiescence of M≥6.5 earthquakes appeared in South American block and its vicinity during the period from 2007 to 2009, and the quietude state has been disappeared three months before the Chile Mw8.8 earthquake; ④ The deep and intermediate-depth earthquake activity has been noticeablely strengthened in the subduction zone of South American block since 1993; ⑤The great Chile earthquake shows that global seismicity is still in the active period of Mw≥8.5 earthquakes since 2004. Based on the characteristics of the former two active periods, several great earthquakes with Mw≥8.5 would take place in a few years. In addition, the circum-Pacific seismic belt would be the main region for Mw≥8.0 earthquakes.
基金This project was sponsored by the National Science Foundation, China
文摘This paper offers a positive research result of TIP before 16 strong earthquakes in North and Southwest China and their nearby areas since 1979 by using improved algorithm M8.The result showed that 14 of them were determined to occur within the times of increased probability.TIP precaution occupies about 37% of the total space-time domain.That means we have made quite good results of intermediate-term prediction of strong earthquakes.So the method could be used as one of the useful means of the intermediate-term prediction of strong earthquakes.
