Source of the 6 February 2013 <i>M</i>_w = 8.0 Santa Cruz Islands Tsunami

• Main Authors: F. Romano, I. Molinari, S. Lorito, A. Piatanesi
• Format: Article
• Language: English
• Published: Copernicus Publications 2015-06-01
• Series: Natural Hazards and Earth System Sciences
• Online Access: http://www.nat-hazards-earth-syst-sci.net/15/1371/2015/nhess-15-1371-2015.pdf
• ISSN: 1561-8633; 1684-9981

On 6 February 2013 an <i>M</i>_w = 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-wave inversion optimized with tsunami forward modelling at DART buoys (Lay et al., 2013) and with inversion of teleseismic body and surface waves (Hayes et al., 2014a). The two studies also use different hypocentres and different planar fault models and found quite different slip models. In particular, Hayes et al. (2014a) argued for an aseismic slip patch SE from the hypocentre. We here develop a 3-D 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.