Collaborative Research: Earthquake triggering by slow slip events beneath Kilauea's south flank

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(a) Technical description This project involves the analysis of data from a temporary NSF-funded seismometer deployment on the south flank of Kilauea volcano, Hawaii, which we designed and deployed in anticipation of a "slow slip event" (SSE) that occurred in June 2007. The temporary seismic array recorded high levels of background seismicity as well as two swarms of flank earthquakes: one in June 2007, triggered by the expected SSE, and another in April 2007, possibly from a pore pressure change on the detachment fault beneath Kilauea's flank induced by the dynamic waves from the Mw 8.1 Solomon Islands earthquake. Our efforts involve picking and locating microearthquakes recorded on the temporary array and the USGS Hawaiian Volcano Observatory seismic network, obtaining focal mechanisms from first motion polarities, and performing double-difference tomography. We will integrate the results of our high precision study with other observations of seismicity and deformation for this region. We expect to make progress on a number of important questions regarding the tectonic framework and background seismicity patterns of Kilauea's south flank, the relation of the triggered seismic swarms to the geodetically observed SSE's, the possible existence of triggered Hilina Pali normal faulting earthquakes, and the frictional behavior of the detachment.(b) Nontechnical explanation We will study earthquakes occurring beneath the south flank of Kilauea volcano, Hawaii, taking advantage of data collected by a dense, temporary seismic array. The array was deployed in 2007 with NSF support in anticipation of a "slow slip event" (SSE) that ultimately occurred in June 2007. Our focus will be on the locations and fault geometries of earthquakes triggered by this SSE, and by a second set of earthquakes that may have been triggered by passing seismic waves from a large distant earthquake. This project is important for understanding earthquake, landslide, and tsunami hazards in Hawaii, where the style of faulting ranges from regular earthquakes to slow earthquakes to long-term creep. In particular, understanding the nature of the triggering of small earthquakes by the SSE may provide clues to the triggering of large flank earthquakes such as the damaging 1975 magnitude 7.2 Kalapana earthquake.This project was supported by the Geophysics and Marine Geology & Geophysics Programs and the Experimental Program to Stimulate Competitive Research (EPSCoR).