2022年云南宁蒗5.5级地震前后波速比变化特征  

Characteristics of Wave Velocity Ratio before and after Yunnan Ninglang M_(S)5.5 Earthquake in 2022

作　　者：张天宇 王光明 刘自凤 黑贺堂 ZHANG Tianyu;WANG Guangming;LIU Zifeng;HEI Hetang(Yunnan Earthquake Agency,148 Beichen Road,Kunming 650224,China;Dali Center of China Earthquake Science Experimental Field,Binhai Road,Dali 671000,China)

机构地区：[1]云南省地震局,昆明市650224 [2]中国地震科学实验场大理中心,云南省671000

出　　处：《大地测量与地球动力学》2022年第11期1156-1160,1183,共6页Journal of Geodesy and Geodynamics

基　　金：云南省青年地震科学基金(2021K02)。

摘　　要：为分析2022-01-02云南宁蒗M_(S)5.5地震前后波速比的时空演化特征,采用单台多震和达法,计算2020-01-01~2022-01-10云南数字地震台网记录的满足计算条件的地震震相到时数据,分析云南地区59个台站波速比以及距离震中最近的LGH和NLA台记录的震后序列波速比变化情况。结果表明:1)宁蒗M_(S)5.5地震发生在滇西北波速比高值区域,且该区域随时间推进呈扩大趋势,可能是在孕震过程中震中附近裂隙有流体渗入达到水饱和状态,从而导致波速比增大;2)震中100 km范围内4个台站波速比大致呈现持续下降-发震的演化过程,距离震中最近的LGH台波速比下降时间稍晚于其他3个台站,初步分析认为,波速比变化出现时间与震中距呈负相关;3)震后地震序列波速比变化与余震活动情况具有较好的对应关系,最大余震发生前波速比出现突降变化;当地震序列呈现正常衰减趋势,波速比维持稳定低值。To analyze the temporal and spatial evolution characteristics of wave velocity ratio before and after the January 2,2022 Ninglang M_(S)5.5 earthquake,we use the Wadati method of single station and multi-earthquake,and calculate the phase arrival time data of earthquakes that meet the calculation conditions recorded by Yunnan digital seismic network from January 1,2020 to January 10,2022.We analyze the wave velocity ratios of 59 stations of Yunnan and the wave velocity ratio of post-earthquake sequence recorded by the LGH and NLA stations closest to the epicenter.The results show that:1)Ninglang earthquake occurred in the area with high wave velocity ratio in northwest Yunnan,and the high value area of wave velocity ratio is tending to expand with time.It may be that in the process of earthquake preparation,there is fluid infiltration in the cracks near the epicenter to reach the state of water saturation,resulting in the increase of wave velocity ratio.2)The wave velocity ratios of the 4 stations within 100 km of the epicenter show the evolutionary process of continuous descent and earthquake,the time of wave velocity ratio begins to decline at the LGH station closest to the epicenter later than that of the other three stations.The preliminary analysis shows that the occurrence time of wave velocity ratio is negatively correlated with the epicentral distance.3)There is better correspondence between the wave velocity ratio change of post-earthquake sequence and the activity of aftershocks,the wave velocity ratio sudden drops before the largest aftershock.When the earthquake sequence shows normal attenuation trend,the wave velocity ratio maintains stable low value.

关 键 词：宁蒗地震 单台多震和达法 波速比 地震序列 

分 类 号：P315[天文地球—地震学]