Differentiation of volcanically- and tectonically-driven seismicity at Kilauea
Abstract
Kilauea is associated with abundant seismicity that may result from both volcanic and tectonic driving processes. Due to strong 3D heterogeneity present in the magmatic system, these distinct processes may not operate uniformly everywhere; for example, seaward slumping of the volcanic pile may generate tectonic-like seismicity on the decollement underlying the volcanos south flank. In this work, we aim to differentiate seismicity of magmatic origin from that of tectonic origin around the broader Kilauea volcanic system. We apply an earthquake clustering algorithm to a catalog spanning 1986-2017 to quantify regional variations in earthquake triggering behavior. Within the caldera and rift zones, sequences statistically contain more events than sequences in the amagmatic Kaoiki fault zone and decollement. Caldera and rift sequences are also less likely to have a clearly defined mainshock, and on average trigger fewer events per parent event, reflecting either high-temperature rheology or aseismic forcing from volcanic processes. We map the heterogeneous distribution of swarms around the volcanic system using topological attributes of the clusters. We observe an abundance of swarms characterized by delayed onset of the largest event and a lack of Omori-Utsu decay. Swarm activity is prominent in magma storage and intrusion zones, accounting for roughly 54% of earthquakes within the caldera and 76% of earthquakes at the Loihi submarine volcano, but is virtually absent in amagmatic regions. Swarm seismicity localizes most prominently near the Halemaumau magma reservoir, suggesting that our catalog of swarm activity can capture the spatiotemporal distribution of magma to a high degree of spatial precision. Swarm occurrence in the East Rift Zone strongly correlates with documented intrusion and unrest episodes; swarms also occur within the Pahala Mantle Fault Zone during the documented 2015-2020 magma surge. Caldera-like triggering properties define a planar feature in the Namakani seismic zone that may be magma-bearing. Decomposing seismic catalogs into swarm and tectonic components allows for robust inference of subsurface magmatic processes and their interaction with regional tectonics.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.V23B..04W