Preliminary study of mantle fault zone Earthquakes beneath Hawaii




Worcester, Daniel

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The mantle fault zone is a region of seismicity 30-40 km beneath Hawaii that is not clearly understood or modelled. Seismicity at depths of 30-40 km underneath Kilauea is related to the mantle fault zone. Taking a close look at this area is vital to understanding the processes that are building Hawaii. Using earthquake location data from 2008-2010 this study hopes to add to the structural modeling of this zone. 330 volcano-tectonic (VT) events were analyzed using data provided by the Hawaii Volcano Observatory. P- and S-wave arrivals were picked using HYP software to determine hypocenter locations. Of the 330 VT events 2 were determined to be high quality locations and 41 to be intermediate locations. Using FPFIT software fault plane solutions were determined for each event. 3 events produced high quality FPS and 36 events produced intermediate FPS. A large group of events are clustered beneath the SE flank of Mauna Loa ranging in depth from 26-40 km. The rest appear to be centralized beneath Kilauea’s footprint. Plotting the FPS on a rose diagram show a P-axis on a NNW-SSE direction and the T-axis on a WNW-ESE direction.