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Schlagwörter:
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Zusammenfassung:
The La Plata subduction segment in Central Ecuador is a 50x50 km2, shallow isolated asperity hosting regular Slow Slip Events (SSEs) and seismic swarms. Here, we combine 20 years of seismological and geodetic data to document the history of slip deficit accumulation and its release. Inter-SSEs slip deficit geodetic model reveals that the plate interface appears to be fully locked from the trench down to 15 km depth over a length of 70 km along trench. Analysis of survey-mode GNSS data reveals that a large SSE with equivalent magnitude of Mw 7.2 ruptured the full locked area in 2005. This SSE was synchronous to a large seismic swarm that lasted ~2.5 months, included several M~6 earthquakes, and accounting for 10-15% of the total moment release. Two large SSEs with magnitude of Mw 6.8-6.9 then occurred in 2016 and 2021, rupturing the shallowest part of the locked area. Kinematic slip inversions reveal thatthe 2016 & 2021 SSEs propagated from north to south. Aside the large SSEs, several smaller (Mw 6-6.3) and shorter SSEs occurred in 2010, 2013, 2017 and 2019, involving partial ruptures of the locked patch. All occurred synchronously to seismic swarm. This history allows to provide the evolution of moment accumulation and release through time. It shows that the behavior of the asperity is neither time-predictable nor slip-predictable.
