In 2019, four strong earthquakes of Mw>6.4 occurred successively in Mindanao, Philippines. Based on the reports from the USGS and PHIVOLCS, these earthquakes were dominated by strike-slip ruptures. Whether these earthquakes are temporally and spatially related remained unknown. We characterized the coseismic displacement fields during the earthquake sequence using an InSAR technique with Sentinel-1 SAR data. The InSAR deformation measurements convincingly reveal that the four earthquakes produced distinct coseismic displacement patterns. We estimated the source parameters of the earthquakes with a two-step inversion strategy. The optimal model suggests that the earthquake sequence resulted from the reactivation of a conjugate fault structure that involves two nearly vertical left-lateral strike-slip faults and two high-angle right-lateral strike-slip faults. We calculated Coulomb stress changes from the earthquake sequence, suggesting that the previous strong earthquakes had significant stress-encouraging effects on the following events. The regional velocities based on the GPS analysis suggest that the formation of this conjugate structure is mainly due to the westward movement of the subducting Philippine Sea Plate. This earthquake sequence provides a seismotectonic background for subsequent strong earthquakes and helps to better understand the formation mechanisms and seismotectonic implications of conjugate structure rupturing.

2019年，菲律宾棉兰老岛连续发生了4次Mw> 6.4以上的强地震。根据USGS和PHIVOLCS的报告，这些地震以走滑断裂为主。这些地震是否与时间和空间有关尚不清楚。我们使用Sentinel-1 SAR数据的InSAR技术对地震序列中的同震位移场进行了表征。InSAR变形测量结果令人信服地表明，四次地震产生了独特的同震位移模式。我们采用两步反演策略估算了地震的震源参数。最佳模型表明，地震序列是由共轭断层结构的重新激活引起的，共轭断层结构包括两个近乎垂直的左走向走滑断层和两个大角度右走向走滑断层。我们根据地震序列计算出库仑应力变化，这表明先前的强地震对随后的事件具有显着的激励作用。基于GPS分析的区域速度表明，这种共轭结构的形成主要是由于俯冲菲律宾海板块向西运动所致。该地震序列为随后的强地震提供了地震构造背景，并有助于更好地理解共轭结构破裂的形成机制和地震构造意义。我们根据地震序列计算出库仑应力变化，这表明先前的强地震对随后的事件具有显着的激励作用。基于GPS分析的区域速度表明，这种共轭结构的形成主要是由于俯冲菲律宾海板块向西运动所致。该地震序列为随后的强地震提供了地震构造背景，并有助于更好地理解共轭结构破裂的形成机制和地震构造意义。我们根据地震序列计算出库仑应力变化，这表明先前的强地震对随后的事件具有显着的激励作用。基于GPS分析的区域速度表明，这种共轭结构的形成主要是由于俯冲菲律宾海板块向西运动所致。该地震序列为随后的强地震提供了地震构造背景，并有助于更好地理解共轭结构破裂的形成机制和地震构造意义。基于GPS分析的区域速度表明，这种共轭结构的形成主要是由于俯冲菲律宾海板块向西运动所致。该地震序列为随后的强地震提供了地震构造背景，并有助于更好地理解共轭结构破裂的形成机制和地震构造意义。基于GPS分析的区域速度表明，这种共轭结构的形成主要是由于俯冲菲律宾海板块向西运动所致。该地震序列为随后的强地震提供了地震构造背景，并有助于更好地理解共轭结构破裂的形成机制和地震构造意义。