摘要
在中国西部及邻区有一个以中国南北地震带—蒙古东部地震带、喜马拉雅地震带和帕米尔—天山—阿尔泰山—蒙古西部地震带为3条边而组成的巨型中亚三角形地震带,其大地震发生的强度之大、频度之高以及重复率之高、重复周期之短,在世界大陆上绝无仅有。这些大地震在空间上受到大地构造位置、构造应力场-滑移线场、介质力学条件、壳内低阻流变层和先存力学脆弱带等五位一体的复合控制,震中主要分布于3条边与活动断裂带交叉处的中—上地壳中;在时间上存在以21.5 a±为最小单元的多种周期。印度板块的持续顶撞和推挤,是该带大地震孕育的能源,而太阳黑子活动和地球自转速率变化可能是该带地震的触发因素。以2001年昆仑山大地震和2008年汶川大地震为标志,中亚三角形地震带可能进入了一个新的107.5 a活动中周期。果真如此,则未来数十年内在该三角形的3条边及其周缘,可能分别发生若干个M≥8.0级大地震和多个M≥7.0级强地震。
There is a giant triangle seismic zone in Central Asia,which is composed of the China North-South Seismic Belt-Mongolia Eastern Seismic Zone,the Pamir-Tianshan-Altay-Mongolia Western Seismic Belt and the Himalayan Seismic Belt,forming the three sides of the triangle.The high-intensity,high frequentness,high repetition rate,and short repeat cycle of large earthquakes in the triangle seismic zone are unique in the continents of the world.These large earthquakes were controlled complexly by tectonic location,tectonic stress field,slip-line field,media mechanics conditions,low resistance rheological layer in the earth＇s crust,and pre-existing mechanical fragile zones.The epicenters located mainly in middle-upper crust of the intersection between the three sides and the active faults.The minimum interval between two earthquakes was 21.5± years.The continued push from the Indian plate was the dynamic sources inducing such a large earthquake,whereas the sunspot activity and the change in autorotation rate of the earth may be the triggered factors for the earthquake.The 2001 Kunlun large earthquake and 2008 Wenchuan large earthquake may be the symbol mark suggesting that the triangle seismic zone in Central Asia has entered a new active period of 107.5 years.If that is true,the large earthquakes ranging from M≥7.0 to M≥8.0 may occur potentially around the three sides of the triangle in the future decades.
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2010年第5期193-205,共13页
Earth Science Frontiers
关键词
汶川大地震
中亚三角形地震带
力学脆弱带
构造应力场
滑移线场
介质力学条件
壳内低阻流变层
Wenchuan large earthquake
triangle seismic zone in Central Asia
mechanical fragile zone
tectonic stress field
slip line field
media mechanical conditions
low resistance rheological layer in the crust
