GNSS资料解译2022年泸定M_(W)6.6地震

Interpretation of the 2022 Luding M_(W)6.6 earthquake based on GNSS data

使用泸定M_(W)6.6地震100 km范围内的10个高频GNSS站点和150 km范围内的36个静态GNSS站点资料解译了本次地震的发震特征.高频GNSS观测结果表明,(1)本次地震总的能量释放时间约为17 s,主要能量释放时间约为11 s;(2)距离起始震中约7.6 km的磨西(MOXI)站点,其东西向震动幅度(约29 cm)略大于南北向(约26 cm),但南北向同震位移(约9.31 cm)却明显大于东西向(约1.80 cm).MOXI站高程方向似乎在瞬间发生了下沉错动;(3)根据地震起始时间与GNSS地震动峰值到达时间推测,地震动峰值能量向南北两侧传播的速度基本相当;(4)高频GNSS资料反演得到的本次地震的矩心深度(2 km)明显浅于GCMT结果(18.4 km).使用36个静态GNSS站点资料进一步反演了矩心深度和断层滑动模型.结果表明,近场GNSS资料约束的本次地震的矩心深度较浅(不超过6 km)、断层面倾角较陡(86°或者更大),且产生了明显的地表破裂.

We employed 10 high rate GNSS sites located within 100 km of the M_(W)6.6 Luding earthquake and 36 static GNSS sites located within 150 km of this seismic event to interpret its seismic characteristics.High rate GNSS results suggest that,(1)the total seismic energy was released in 17 seconds and the main energy was released in the first 11 seconds;(2)the MOXI site located 7.6 km away from the epicenter shows greater amplitude of ground vibration in W-E direction than N-S direction,but the permanent coseismic offset in the W-E direction(~1.90 cm)is significantly less than that of the N-S direction(~9.31 cm).The subsidence of this site seems to take place suddenly;(3)based on the starting time of the earthquake and the arrival time of the seismic wave crest at the GNSS sites,we deduce that the propagation speeds of the peak ground motion to the south and the north direction of the epicenter are almost the same;(4)the high rate GNSS inverted centroid depth(2 km)is much shallower than that of the GCMT solution(18.4 km).To study such depth disparity,we further employ 36 static GNSS data to invert for the centroid depth and fault slip distribution.The slip model indicates that the centroid depth of this event is shallow(not deeper than 6 km),the dipping angle of the ruptured fault is sharp(86°or higher)and distinct fault crack may be observed on the surface.