Geophysical modeling of collapse-prone zones at Rumble III seamount, southern Pacific Ocean, New Zealand

Catastrophic collapses of submarine volcanoes have the potential to generate major tsunami,
threatening many coastal populations. Recognizing the difficulties surrounding anticipations of these
events, quantitative assessment of collapse-prone regions based on detailed morphological, geological,
and geophysical mapping can still provide important information about the hazards associated with these
collapses. Rumble III is one of the shallowest, and largest, submarine volcanoes found along the
Kermadec arc, and is both volcanically and hydrothermally active. Previous surveys have delineated
major collapse features at Rumble III ; based on time-lapse bathymetry, dramatic changes in the volcano
morphology have been shown to have occurred over the interval 2007–2009. Furthermore, this volcano is
located just 300 km from the east coast of the North Island of New Zealand. Here, we present a
geophysical model for Rumble III that provides the locations and sizes of potential weak regions of this
volcano. Shipborne and near-seafloor geological and geophysical data collected by the AUV Sentry are
used to determine the subsurface distribution of weak and unstable volcanic rocks. The resulting model
provides evidence for potentially unstable areas located in the Southeastern flank of this volcano which
should be included in future hazard predictions.