计算2019年11月21日老挝 M_S6.0 地震前后(2019年10月16日—12月15日)震中位置(19.50°N,101.35°E)的潮汐变化。发震时刻引潮力处于高相位点附近,显示引潮力的诱震作用属于典型正断层走滑作用类型。以此引潮力变化周期的各低相位点时间(10月28日、11月13日、11月27日)分别为背景,计算研究区(13°N～23°N,99°E～109°E)范围内,NOAA射出长波辐射数据产品(OLR)各引潮力周期时段长波辐射异常分布及变化。结果显示,无震时的引潮力变化的A、C周期,震中附近无OLR变化; 发震的引潮力变化B周期,该地区震前OLR仅震中发生了显著而连续异常变化过程: 在空间上OLR异常分布在老挝北部NE-SW走向的奠边府断裂带上,且与震中位置高度吻合,经历了起始增强—异常增强—峰值—减弱—发震—平静的演化过程,与岩石应力加载破裂演化即初始微动破裂—扩张破裂—应力闭锁—地震暴发—平静各阶段力学过程相同; 表明天体引潮力对达到临界状态的活跃断层有触发作用,OLR异常则是地震构造应力应变活动过程的辐射表征。

For the M_S6.0 earthquake in Laos on November 21,2019,tidal variations were calculated before and after the earthquake(from October 16 to December 15,2019)at the epicenter(19.50°N,101.35°E). The gravitational tidal force was near its high-phase point at the time of the earthquake,indicating that the induced seismic effect belonged to the typical type of positive fault strike-slip action. The distribution of long wave radiation anomalies and changes in the NOAA Outgoing Long Wave Radiation(OLR)data were calculated for each tidal cycle in the study area(13°N～23°N,99°E～109°E)against the background of the low-phase points of the tidal cycle(October 28,November 13,and November 27). The results show no OLR change near the epicenter during the A and B cycles of no-seismic tidal variation. However,during the C cycle of the tidal change associated with the earthquake,a significant and continuous OLR anomaly was observed only at the epicenter. Spatially,the OLR anomalies are distributed along the Dien Bien Phu fault zone in northeastern-southwestern trending northern Laos,coinciding with the epicenter location. Temporally,the anomalies followed a process of warming,anomalous enhancement,peak,attenuation,seismicity,and calm. This pattern aligns with the mechanical process of rock stress-loaded rupture evolution:initial micro-motion rupture,dilatational rupture,stress locking,seismicity,and calm. These observations indicate that the tidal force of celestial bodies can induce activity in faults that are in a critical state. Furthermore,OLR anomalies represent the stress-strain processes within the earthquake structure.

P315

援老挝国家地震监测台网项目(204182501)、亚洲合作资金防震减灾领域合作项目“中国-东盟地震灾害监测防御能力提升项目”(12499901)、风云三号03批气象卫星工程地面应用系统地质灾害监测应用(FY-3(03)-AS-11.10-ZT)共同资助