地震研究

基于2021年云南漾濞MS6.4地震震中周围40 km范围内仅有的2 个强震台近场强震记录进行基线校正并给出同震位移。同时分析强震和GPS资料呈现的永久位移场特征,利用快速获取的GPS同震位移场和InSAR 升、降轨资料分别独立和联合反演该地震的震源滑动模型,并进一步展现全空间预测位移场分布。结果表明:①漾濞地震水平同震位移场呈现以右旋走滑为主的错动。②GPS和InSAR独立和联合反演所得的震源静态滑动范围基本一致,均呈现单侧破裂的总体特征,即主要滑动均发生在震中东南部。6种模型的最大滑动量分别为0.74 m、0.66 m、0.44 m、0.45 m、0.47 m和0.47 m,反演的矩震级为MW5.9～6.3。③根据震源滑动模型正演所得的漾濞地震全空间预测水平同震位移场与实际观测位移场一致性较好,震中南、北两侧向内挤压,东、西两侧向外拉张,符合走滑型地震所产生的四象限位移场分布特征。

On the basis of the near-field strong motion records within 40 km around the epicenter of the Yangbi MS6.4 earthquake in Yunnan on May 21,2021,we used an improved automatic empirical baseline correction method to estimate the co-seismic displacement.We analyzed the characteristics of strong motion and GPS co-seismic displacement field.We inverted independently and jointly the source slip model using GPS data and InSAR ascending-and descending-orbit data,and further proposed the distribution of the predicted,full-space,co-seismic displacement field based on the slip model.The results showed that:(1)The horizontal co-seismic displacement field showed that the fault dislocation was dominated by right-lateral strike-slip.(2)The static slip range of the source obtained by independent-and joint-inversion of GPS and InSAR was basically the same.The maximum slip occurred in the south of the epicenter.The maximum slips of the source by the 6 models were respectively 0.74 m,0.66 m,0.44 m,0.45 m,0.47 m and 0.47 m.The inverted MW ranged from 5.9 to 6.3.(3)The predicted,full-space,horizontal,co-seismic displacement field of the Yangbi earthquake by the slip model was in good agreement with the observed,horizontal,co-seismic displacement field.The north and south parts of the epicenter were compressing inward,while the east and west parts were stretching outward.This was consistent with the characteristics of the co-seismic displacement field produced by a strike-slip earthquake.

引言
1 研究区概况及资料选取与处理
2 同震位移场特征
3 震源滑动模型反演
4 结论

图1 2021年云南漾濞MS6.4地震震中周边台站空间分布及余震震中分布<br/>Fig.1 Distribution of stations around the epicenter of the MS6.4 Yangbi earthquake and the aftershock epicenters

图1 2021年云南漾濞MS6.4地震震中周边台站空间分布及余震震中分布
Fig.1 Distribution of stations around the epicenter of the MS6.4 Yangbi earthquake and the aftershock epicenters

图2 53YBX台经基线校正后的加速度(a)、速度(b)和位移(c)时程<br/>Fig.2 The time-history of acceleration(a),velocity(b)and displacement(c)at 53YBX station after baseline correction

图2 53YBX台经基线校正后的加速度(a)、速度(b)和位移(c)时程
Fig.2 The time-history of acceleration(a),velocity(b)and displacement(c)at 53YBX station after baseline correction

图3 基于强震(红色)和GPS(蓝色)观测数据所得的漾濞MS6.4地震水平向(a)和垂直向(b)同震位移场(断裂同图1)<br/>Fig.3 Comparison of horizontal(a)and vertical(b)co-seismic displacement fields derived from the strong motion observation(red)with the ones derived from GPS observation(blue)

图3 基于强震(红色)和GPS(蓝色)观测数据所得的漾濞MS6.4地震水平向(a)和垂直向(b)同震位移场(断裂同图1)
Fig.3 Comparison of horizontal(a)and vertical(b)co-seismic displacement fields derived from the strong motion observation(red)with the ones derived from GPS observation(blue)

图4 漾濞地震InSAR降轨(a)、升轨(b)同震位移场(视线向)<br/>Fig.4 The co-seismic LOS displacement field of InSAR-descending(a)and InSAR-ascending(b)in the Yangbi MS6.4 earthquake event

图4 漾濞地震InSAR降轨(a)、升轨(b)同震位移场(视线向)
Fig.4 The co-seismic LOS displacement field of InSAR-descending(a)and InSAR-ascending(b)in the Yangbi MS6.4 earthquake event

表1 反演所用地壳速度模型<br/>Tab.1 Crustal velocity model near the epicenter for inversion

表1 反演所用地壳速度模型
Tab.1 Crustal velocity model near the epicenter for inversion

图5 基于GPS(a)、InSAR降轨(b)和升轨(c)资料独立反演所得的震源滑动模型,GPS分别联合InSAR降轨资料(d)、升降轨资料(升轨模型权重为1)(e)以及升降轨资料(升轨模型权重为0.5)(f)反演所得的震源滑动模型<br/>Fig.5 Slip models obtained by inversion of GPS data(a), InSAR-descending data(b),and InSAR-ascending data(c)repectively; Slip models obtained by inversion of GPS data combined with InSAR-descending data(d), GPS data combined with InSAR-ascending data(weight=1)(e); A slip model obtained by inversion of GPS data combined with InSAR-descending data and InSAR-ascending data(weight=0.5)(f)

图5 基于GPS(a)、InSAR降轨(b)和升轨(c)资料独立反演所得的震源滑动模型,GPS分别联合InSAR降轨资料(d)、升降轨资料(升轨模型权重为1)(e)以及升降轨资料(升轨模型权重为0.5)(f)反演所得的震源滑动模型
Fig.5 Slip models obtained by inversion of GPS data(a), InSAR-descending data(b),and InSAR-ascending data(c)repectively; Slip models obtained by inversion of GPS data combined with InSAR-descending data(d), GPS data combined with InSAR-ascending data(weight=1)(e); A slip model obtained by inversion of GPS data combined with InSAR-descending data and InSAR-ascending data(weight=0.5)(f)

表2 基于相同断层面使用不同资料反演所得滑动模型结果比较<br/>Tab.2 Slip model parameters obtained by GPS and InSAR based on the same of fault parameters

表2 基于相同断层面使用不同资料反演所得滑动模型结果比较
Tab.2 Slip model parameters obtained by GPS and InSAR based on the same of fault parameters

图6 漾濞MS6.4地震的全空间预测水平同震位移场<br/>Fig.6 The full-space prediction of the horizontal co-seismic displacement field of the Yangbi MS6.4 earthquake

图6 漾濞MS6.4地震的全空间预测水平同震位移场
Fig.6 The full-space prediction of the horizontal co-seismic displacement field of the Yangbi MS6.4 earthquake

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备注

引言

1 研究区概况及资料选取与处理

2 同震位移场特征

3 震源滑动模型反演

4 结论

期刊信息