Bell Andrew F, Hernandez Stephen, McCloskey John, Ruiz Mario, LaFemina Peter C, Bean Christopher J, Möllhoff Martin
School of GeoSciences, University of Edinburgh, Edinburgh EH9 3FE, UK.
Instituto Geofísico, Escuela Politécnica Nacional, Quito, Ecuador.
Sci Adv. 2021 Sep 24;7(39):eabh0894. doi: 10.1126/sciadv.abh0894.
The propensity for dynamic earthquake triggering is thought to depend on the local stress state and amplitude of the stress perturbation. However, the nature of this dependency has not been confirmed within a single crustal volume. Here, we show that at Sierra Negra volcano, Galápagos Islands, the intensity of dynamically triggered earthquakes increased as inflation of a magma reservoir elevated the stress state. The perturbation of short-term seismicity within teleseismic surface waves also increased with peak dynamic strain. Following rapid coeruptive subsidence and reduction in stress and background seismicity rates, equivalent dynamic strains no longer triggered detectable seismicity. These findings offer direct constraints on the primary controls on dynamic triggering and suggest that the response to dynamic stresses may help constrain the evolution of volcanic unrest.
动态地震触发的倾向被认为取决于局部应力状态和应力扰动的幅度。然而，这种依赖性的本质尚未在单一地壳区域内得到证实。在此，我们表明在加拉帕戈斯群岛的塞拉内格拉火山，随着岩浆库的膨胀提高了应力状态，动态触发地震的强度增加。远震面波内短期地震活动的扰动也随峰值动态应变增加。在快速喷发后的沉降以及应力和背景地震活动率降低之后，同等的动态应变不再触发可检测到的地震活动。这些发现为动态触发的主要控制因素提供了直接限制，并表明对动态应力的响应可能有助于限制火山活动的演变。
