尼泊尔8.1级地震对西藏地区及邻区地震形势的影响  

Seismic Tendency around the Tibet Region after the 2015 M8.1 Nepal Earthquake

作　　者：旦增 朱德富 土登次仁 益西拉姆 曹华文 米玛次仁 

机构地区：[1]西藏自治区地震局,西藏拉萨850000

出　　处：《四川地震》2016年第2期34-37,共4页Earthquake Research in Sichuan

摘　　要：依据西藏地震台网地震目录,对比了美国地震台网(NEIC)记录,收集了喜玛拉雅弧型带和西藏地区及邻区5级以上的历史地震资料,同时收集了2015年4月25日尼泊尔8.1级和西藏定日5.9级地震机制解资料。研究了喜玛拉雅弧型带发生的8级地震对青藏块体产生的重要影响,分析了西藏定日5.9级与尼泊尔8.1级两次地震的关系。结果显示:2015年4月25日尼泊尔8.1级地震动态触发了西藏日喀则地区定日5.9级地震,反映了青藏块体本身具有较高的应力水平。震源机制解显示:2015年4月25日尼泊尔8.1级地震当日,西藏定日发生的5.9级地震为近南北走向的正断层张性活动,属于藏南拆离系与控制近南北向拉张断陷盆地的正断层型地震,西藏日喀则地区的定日5.9级地震与尼泊尔8.1级地震属于不同类型的地震。喜玛拉雅弧型带发生的8级地震会对青藏块体产生重要影响,2015年4月25日尼泊尔8.1级地震和历史震例均显示喜玛拉雅弧型带发生的8级地震会对青藏块体产生重要的影响,在1934年1月15日尼泊尔MS8.3级地震后三年内地震呈现北东—南西走向展布,2015年4月25日尼泊尔8.1级地震后西藏地区及邻区地震活动也呈现较明显北东向成带分布;2015年4月25日尼泊尔8.1级地震后,西藏地区出现3级以上地震起伏性丛集活动,该区的地震震级水平短时间也略显升高。We use the earthquake catalogue of the Seismic Network of Tibet Autonomous Region and compare seismic data with the records of NEIC. At the same times we collect the historical earthquakes over M5. 0 occurred in the Himalayan Arc Belt and Tibet Region and the earthquake mechanism solutions of both the 2015 M8. 1 Nepal Earthquake and the M5. 9 Dingri Earthquake. This M8. 1 Earthquake occurred in the Himalayan Arc Belt has heavily affected the seismic tendency of the Qing-Tibet block region. We also discuss the relationship between the 2015M8. 1 Nepal Earthquake and the M5. 9 Dingri Earthquake. Our results show that the 2015 M8. 1 Nepal Earthquake triggered dynamically the M5. 9 Dingri Earthquake and the crust of Tibet has a high stress level. The earthquake mechanism solutions show that the M5. 9 Dingri Earthquake just on 25 April 2015 resulted from the occurring of the M8. 1 Nepal Earthquake and from the tensional activity of normal fault with the direction of North-South in the Tibet block as well. The seismic activity is controlled by tension normal faults distributed in both the south Tibet Detachment System and tensional graben basin with the South-north direction. However the M5. 9 Dingri Earthquake and the M8. 1 Nepal Earthquake are belong to different type of earthquakes. The strong earthquakes in Himalayan Arc belts affect heavily the block in Tibet region. For three years after the M8. 3 Earthquake on 15 January 1934 there was an earthquake swarm with the northeast-southwest direction. Some situation happened again. After the M8. 1 Nepal Earthquake on 25 April 2015,there was a clear earthquake swarm with the northeast-southwest direction. Then there were grouped swarms about M3. 0 earthquakes and the seismicity level increased in short time.

关 键 词：尼泊尔8.1级地震 西藏定日5.9级地震 喜玛拉雅弧型带 震源机制解 

分 类 号：P315.71[天文地球—地震学]