2023年积石山6.2级地震地脉动应变场前兆异常特征
PRECURSORY ANOMALY CHARACTERISTICS OF GROUND PULSATION STRAIN FIELD IN THE 2023 JISHISHAN M6.2 EARTHQUAKE
张晓清 1袁伏全 1胡乐银 2余娜 1杨晓霞1
作者信息
- 1. 青海省地震局,青海西宁 810005
- 2. 北京市地震局,北京10080
- 折叠
摘要
利用青海省和周边地区宽频带数字地震台网记录的地脉动低频信号(频段为40～50 s),计算得到区域应变场,基于应变场空间分布和强度随时间进程变化特点,对2023年12月18日积石山6.2级地震前区域水平应变场进行分析.结果显示:水平应变场空间上体现为,震前15 d左右在震中周围出现拉张和压缩交替的应变梯度带,张性与压性区域应变强度和分布面积大体相当;连续波形应变强度在时间上体现为,随着地震的临近,震中周边区域应变强度在震前15 d左右达到最大值,约为背景值的5倍,随后几天下降至最高点之前水准,15 d之后发震.
Abstract
Using the broadband digital seismic network in Qinghai and surrounding areas to record continuous monitoring data of low-frequency signals(40-50 seconds),this study analyzed the horizontal strain field of regional ground pulsation before the 6.2 magnitude Jishishan earthquake on December 18,2023,based on the spatial distribution characteristics of the ground pulsation strain field and the changes in strain field intensity over time.The abnormal characteristics of the strain area before the earthquake were summarized.The results show that before the 6.2-magnitude Jishishan earthquake,the horizontal strain field was spatially manifested as a strain gradient zone with alternating tension and compression around the epicenter about 15 days before the earthquake,and the strain intensity and distribution area in the tension and compression regions were roughly equivalent;The intensity of ground pulsation strain is reflected in time.As the time of the earthquake approaches,the strain intensity in the surrounding area of the epicenter reaches its maximum value within 15 days before the earthquake,which is about 5 times the background value.In the following days,the high strain value drops to the level before the peak,and the earthquake occurs 15 days later.
关键词
积石山6.2级地震/地脉动应变场/时空特征Key words
Jishishan 6.2 magnitude earthquake/Microtremors strain field/Spatiotemporal character-istics引用本文复制引用
出版年
2025
NETL
NSTL
万方数据