2013 年芦山7.0 级地震前后重力场变化特征

The variation characteristics of gravity field before and after of the 2013 Lushan MS7． 0 earthquake

摘要:

利用四川地区2010 ～ 2013 年流动重力观测数据作出的重力场动态变化图像和重力段差时序变化图像，对芦山7. 0 级地震前后的重力场动态演化特征进行了研究，结果表明:震前重力场经历了约3 年的重力增大和约1 年的减小变化，重力变化呈“上升→加速上升→减速上升→加速下降→减速下降”特征; 芦山地震发生在重力场变化由下降转为上升的回调过程中;震后重力场变化以较快的速度恢复到接近震前状况，并出现重力正值变化异常区域;临震前震中区域重力场变化数值较小，构造带活动速度变慢。

Abstract:

On the basis of gravity observation data from 2010 to 2013 in the Sichuan area，we draw dynamic pictures of gravity field and curves of gravity segment difference at some measuringsections． These pictures have been used to study the dynamic evolution characteristics of the gravity field before and after the Lushan MS7． 0 earthquake． The result shows that the gravity field has experienced increase change about 3 years and decreases change about 1 year before the earthquake in a gravity field variation pattern of rise→accelerated rise→slow rise→accelerated decline→slow decline． The Lushan earthquake occurred in the callback procedure of the gravity field from decline to increase． The gravity field changes returned to near pre-earthquake conditions at a faster rate after the earthquake with the anomalies in positive gravity change areas． The gravity field changes of epicenter region was smaller before the earthquake and the tectonic activities were slower．