Instituto de Ciencias de la Tierra, TAQUACh, Universidad Austral de Chile, Valdivia, 5111430, Chile.
Millennium Nucleus The Seismic Cycle Along Subduction Zones, Valdivia, Concepción, Valparaíso., 5111430, Chile.
Nat Commun. 2018 Aug 30;9(1):3527. doi: 10.1038/s41467-018-05989-6.
Great megathrust earthquakes arise from the sudden release of energy accumulated during centuries of interseismic plate convergence. The moment deficit (energy available for future earthquakes) is commonly inferred by integrating the rate of interseismic plate locking over the time since the previous great earthquake. But accurate integration requires knowledge of how interseismic plate locking changes decades after earthquakes, measurements not available for most great earthquakes. Here we reconstruct the post-earthquake history of plate locking at Guafo Island, above the seismogenic zone of the giant 1960 (M = 9.5) Chile earthquake, through forward modeling of land-level changes inferred from aerial imagery (since 1974) and measured by GPS (since 1994). We find that interseismic locking increased to ~70% in the decade following the 1960 earthquake and then gradually to 100% by 2005. Our findings illustrate the transient evolution of plate locking in Chile, and suggest a similarly complex evolution elsewhere, with implications for the time- and magnitude-dependent probability of future events.
特大地震是由几十年来积累的地震能量在瞬间释放引起的。目前通常通过整合上一次大地震以来的地震间板块闭锁速率来推断地震矩亏损（未来地震可用的能量）。但是，准确的整合需要了解地震后几十年间地震间板块闭锁如何变化，而大多数大地震都无法提供这方面的测量数据。在这里，我们通过对 1960 年（M = 9.5）智利大地震震源区上方的瓜福岛的航空影像（自 1974 年以来）和 GPS 测量（自 1994 年以来）推断出的海平面变化进行正向建模，重建了该岛地震后的板块闭锁历史。我们发现，在 1960 年地震后的十年内，地震间的闭锁增加到约 70%，然后在 2005 年逐渐增加到 100%。我们的研究结果说明了智利板块锁定的瞬态演化，并暗示了其他地方可能存在类似的复杂演化，这对未来事件的时间和幅度依赖性概率具有重要意义。
