Mark Behn, Geology & Geophysics
Jeff McGuire, Geology & Geophysics
DOEI Project Funded: 2005
Massive slope failure and debris avalanches on the flanks of oceanic volcanoes have been linked to tsunami generation in the Pacific and Atlantic Oceans. However the process by which the flanks of active volcanoes deform remains poorly understood. One of the best-studied active volcanic landslides is the Hilina slump on the southeast flank of Kilauea volcano, Hawaii. Geodetic measurements and field observations on land show that the Hilina slump breaks away along a system of seaward dipping normal faults that transport material to the southeast at rates of ~10 cm/yr. This extension may represent the upper-flank expression of a massive slump sliding coherently seaward. Alternatively, several recent studies have proposed that volcanic spreading associated with magma injection at the summit of Kilauea places the upper subaerial flanks in extension, while simultaneously generating compression and thrust faulting in the lower submarine flanks. If correct, this model implies a more stable flank configuration, with less potential for massive landslides and tsunami-genesis. Unfortunately distinguishing between these models for the Hilina slump has been difficult because much of the deformation appears to be accommodated aseismically and to date no submarine geodetic measurements have resolved horizontal motions on the flank.
In this study we will deploy a new acoustic extensometer system under development at WHOI to monitor deformation in Kilauea’s submarine flank. The rapid deformation rates combined with the localized region of compression predicted by the volcanic spreading model should be well resolved during our year-long deployment. In addition, the continuous time series obtained by the extensometer system will be compared to onshore continuous GPS data to look for correlations between transient periods of deformation. The deployment cruise is scheduled for October 2005 aboard the RV Kilo Moana and the recovery leg planned for late spring/early summer 2006.