Publication Date:
2019
Description:
Abstract
The mobile south flank of Kīlauea Volcano hosts two normal fault systems, the Koa'e fault system (KFS) and the Hilina fault system (HFS). In historical time, at least three M〉6.5 earthquakes have occurred on the basal detachment of the Kīlauea Volcano's south flank, with the most recent being the May 4, 2018 M6.9 earthquake. Here we analyze kinematic GPS data collected from 2001 to 2017, and InSAR data before, during and after the 2018 M6.9 earthquake to determine the crustal motion across the HFS and KFS faults. Our results indicate that the HFS faults did not significantly slip during the interseismic period from 2007 to 2011. Despite its substantial magnitude, InSAR shows that the 2018 M6.9 earthquake triggered sub‐cm level slip along sections of the previously mapped HFS branches. Up to 20 cm of offset occurred on what appears to be a newly formed (or previously unknown) fault near the eastern end of the HFS. During the 3 months following the M6.9 earthquake, up to more than 30 cm of slip occurred along the KFS, which helps accommodate rapid large‐scale subsidence of Kīlauea's summit region as large volumes of summit reservoir magma fed the lower East Rift Zone eruption. The HFS appears to activate only in concert with large earthquakes on the basal detachment. The KFS, on the other hand, moves both seismically during small local earthquakes, and aseismically in response to nearby earthquakes and caldera subsidence.
Print ISSN:
2169-9313
Electronic ISSN:
2169-9356
Topics:
Geosciences
,
Physics
