邢台、渤海、海城和唐山大地震震中区现今应变场的基本特征  

Basic characteristics of current strain field in the epicentral area of Xingtai,Bohai,Haicheng and Tangshan strong earthquake

作　　者：李延兴[1] 徐杰[2] 陈聚忠[1] 张静华[1] 张中伏[1] 

机构地区：[1]中国地震局第一监测中心,天津300180 [2]中国地震局地质研究所,北京100029

出　　处：《华北地震科学》2006年第2期36-39,共4页North China Earthquake Sciences

基　　金：国家自然科学基金项目(批准号是:40238059和40474036)

摘　　要：根据近十多年来华北地区GPS网的观测资料,分别计算了邢台、渤海、海城和唐山4次Ms7级以上大地震震中区现今应变场的主应变参数。计算结果表明,由GPS观测得到的邢台、渤海、海城、唐山地震震中区的主压应变轴方向与震前震中及周围地区的主压应力轴方向是一致的或基本上是一致的,这说明震中区的局部应力场经过震后30～40年的调整,震中区局部的应力场已基本上与区域应力场趋于一致。当前,邢台地震区主压应变率很小为-0.352×10^-9/yr,主张应变率较大为3.306×10^-9/yr,张应变占绝对优势,地壳处于拉张状态;在渤海地震区,主压应变率为2.593×10^-9/yr,比主张应变率（2.947×10^-9/yr）略小一些,二者比较接近;在海城地震区,主压应变率为1.276×10^-9/yr,小于主张应变率（2.940×10^-9/yr）,地壳以张应变为主;在唐山地震区,主压应变率为4.539×10^-9/yr,大于主张应变率（3.477×10^-9/yr）,压应变占优势。The principal strain parameters of current strain field in epicenter area corresponding to 4 Ms≥7 earthquakes, which was Xingtai, Bohai, Haicheng and Tangshan earthquake, are calculated with the GPS data observed in North China GPS network in past decade. The results show that the directions of principal compressive axes from GPS data in the four areas are consistent or basically consistent with that of the direction in epicenter and its adjacent area before the earthquakes. It indicates that, after the adjustment for 30 to 40 years, the local stress field in epicentral area is basically coincident with the regional strain field. At present, the principal compressive strain rate in Xingtai earthquake region is very small, with a magnitude of -0.352×10^-9/yr, and the principal tensile strain rate is relatively large, with a magnitude of 3. 306×10^-9/yr, which shows that the tensile strain in this area is predominated, and the crust is in a tensional state; in Bohai earthquake region, the principal compressive strain rate is -2. 593×10^-9/yr, which is a little bit smaller than the tensile strain rate （2. 947×10^-9/yr） ; in Haicheng earthquake region, the principal compressive strain rate （1.276×10^-9/yr） is smaller than the tensile strain rate （ 2. 940×10^-9/yr）, where is dominated by tensile strain; in Tangshan region, the principal compressive strain rate is 4.539×10^-9/yr , and the tensile strain rate is 3. 447×10^-9/yr,where the crust dominated by compressive strain.

关 键 词：华北大地震 GPS测量 应力场 应变场 

分 类 号：P315.72[天文地球—地震学]