Philippine archipelago (PA) has strong background seismicity,but there is no systematic study of earthquake triggering in this region. There are six earthquakes (M_(w) > 6) occurred between 2018/12/29 and 2019/09/2...Philippine archipelago (PA) has strong background seismicity,but there is no systematic study of earthquake triggering in this region. There are six earthquakes (M_(w) > 6) occurred between 2018/12/29 and 2019/09/29 in PA,which provides an excellent opportunity to investigate the triggering relationship among these events. We calculate the static Coulomb stress changes of the first five events,and find that the local seismicity after the 2018/12/29 M_(w) 7.0 earthquake is mostly associated with positive Coulomb stress changes,including the 2019/05/31 M_(w) 6.1 event,suggesting a possible triggering relationship. However,we cannot rule out the dynamic triggering mechanism,due to increased microseismicity in both positive and negative stress change regions,and an incomplete local catalog,especially right after the first M_(w) 7.0 mainshock. The dynamic stresses from these M_(w) > 6 events are large enough (from 5 kPa to 3532 kPa) to trigger subsequent events,but a lack of seismicity and waveform evidence does not support delayed dynamic triggering among these events,even the shortest time interval is less than 24 hours. In the past 45 years,the released seismic energy shows certain peaks every 5–10 years. However,earthquakes with M_(w) > 6.0 were relatively infrequent between 2004 and 2018 at PA. Hence,it is possible that several regions are relatively late in their earthquake cycles,which would enhance their susceptibility of being triggered by earthquakes at nearby and regional distances.展开更多
基金The National Natural Science Foundation of China under contract Nos 41704049,41890813,91628301 and 41974068the Chinese Academy of Sciences under contract Nos QYZDY-SSW-DQC005 and 133244KYSB20180029+3 种基金the foundation of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)under contract No.GML2019ZD0205the foundation of Youth Innovation Promotion Association,Chinese Academy of Sciences under contract No.YIPA2018385the United States National Science Foundation under contract No.EAR-1736197the Foundation of Science Foundation for the Earthquake Resilience of China Earthquake Administration under contract No.XH20072.
文摘Philippine archipelago (PA) has strong background seismicity,but there is no systematic study of earthquake triggering in this region. There are six earthquakes (M_(w) > 6) occurred between 2018/12/29 and 2019/09/29 in PA,which provides an excellent opportunity to investigate the triggering relationship among these events. We calculate the static Coulomb stress changes of the first five events,and find that the local seismicity after the 2018/12/29 M_(w) 7.0 earthquake is mostly associated with positive Coulomb stress changes,including the 2019/05/31 M_(w) 6.1 event,suggesting a possible triggering relationship. However,we cannot rule out the dynamic triggering mechanism,due to increased microseismicity in both positive and negative stress change regions,and an incomplete local catalog,especially right after the first M_(w) 7.0 mainshock. The dynamic stresses from these M_(w) > 6 events are large enough (from 5 kPa to 3532 kPa) to trigger subsequent events,but a lack of seismicity and waveform evidence does not support delayed dynamic triggering among these events,even the shortest time interval is less than 24 hours. In the past 45 years,the released seismic energy shows certain peaks every 5–10 years. However,earthquakes with M_(w) > 6.0 were relatively infrequent between 2004 and 2018 at PA. Hence,it is possible that several regions are relatively late in their earthquake cycles,which would enhance their susceptibility of being triggered by earthquakes at nearby and regional distances.
