Source of the 6 February 2013 Mw 8.0 Santa Cruz Islands Tsunami

On 6 February 2013 an Mw 8.0 subduction earthquake occurred close to Santa Cruz Islands
at the transition between the Solomon and the New Hebrides Trench. The ensuing tsunami
caused significant inundation on the closest Nendo Island. The seismic source was studied
with teleseismic broadband P waves inversion optimized with tsunami forward modeling at
DART buoys (Lay et al., 2013), and with inversion of teleseismic body and surface waves
(Hayes et al., 2014). The two studies also use different hypocenters and different planar fault
models, and found quite different slip models. In particular, Hayes et al. (2014) argued for
an aseismic slip patch SE from the hypocenter. We here develop a 3D model of the fault
surface from seismicity analysis and retrieve the tsunami source by inverting DART and tide-gauge data. Our tsunami source model features a main slip patch (peak value of ~11 m)
SE of the hypocentre, and reaching the trench. The rake direction is consistent with the
progressively more oblique plate convergence towards the Solomon trench. The tsunami
source partially overlaps the hypothesized aseismic slip area, which then might have slipped
coseismically.

ASTARTE - Assessment, Strategy And Risk
Reduction for Tsunamis in Europe - FP7-ENV2013 6.4-3, Grant 603839; Italian flagship project RITMARE

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