红河断裂带库仑应力演化及未来地震危险性估计

现今地震活动性显示红河断裂带强震主要发生在断裂带的北段，中段长期存在地震空区.为了更好地理解红河断裂带不同段落地震活动性差异和评估未来潜在地震危险性，本研究基于分层半无限空间黏弹性地球模型计算了自1833年嵩明M8.0地震以来，红河断裂带上及其周边共25次强震由于同震应力阶变、震后黏滞松弛和震间构造应力加载的综合作用，红河断裂带上库仑应力变化的演化过程.结果表明，在近180年红河断裂带南北两段得到加载，中段始终位于应力影区，这可能部分解释红河断裂带南北段地震相对活跃、中段长期存在的地震平静现象.假设未来三十余年该地区不再发生大震，考虑震后和震间作用，红河断裂带中段应力影区仍然存在，但范围在缩小；洱源附近、大理至大斗门以北地区、元江以南地区应力增加超过0.1 MPa，可能仍是地震潜在危险区段.

Seismic hazard assessment for the Red River fault: insight from Coulomb stress evolution

Historic strong earthquakes ruptured the northern segment of the Red River fault, while left a seismic gap in the middle segment. To better understand this seismicity pattern and assess the seismic hazard in this region, we investigated the evolution of Coulomb failure stress on the Red River fault since 1833 taking coseismic, postseismic and interseismic deformation into account based on a stratified viscoelastic earth model. In total, 25 large earthquakes were analyzed. The results revealed that both the northern and the southern segments of the Red River fault are loaded, while the stress changes of the central segment remained negative in recent 180 years. This may contribute to the high level of seismicity near the northern and southern segments of the Red River fault and the low level of seismicity in the central segment. The combined prediction of the postseismic and interseismic stress changes on the fault over the next 30 years suggests that this seismic gap of the central segment will be shortened gradually. The segments that surrounding Eryuan, between Dali and north of Dadoumen and south of Yuanjiang may suffer high seismic risk due to the increased stress level.