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The February 6, 2013 M_w 8.0 Santa Cruz Islands earthquake and tsunami

Lay, Thorne and Ye, Lingling and Kanamori, Hiroo and Yamazaki, Yoshiki and Cheung, Kwok Fai and Ammon, Charles J. (2013) The February 6, 2013 M_w 8.0 Santa Cruz Islands earthquake and tsunami. Tectonophysics, 608 . pp. 1109-1121. ISSN 0040-1951. doi:10.1016/j.tecto.2013.07.001.

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The Santa Cruz Islands region has high seismicity near a 90° bend in the boundary between the Pacific and Australian plates. Southward, along the Vanuatu island arc, the Australian plate under-thrusts the Pacific plate in a well-defined subduction zone. Westward, a transpressional, predominantly transform boundary extends to the southern Solomon Islands subduction zone. The Santa Cruz Islands region has upper plate strike-slip and normal faulting, plate boundary under-thrusting, outer rise extensional faulting, and intraplate compressional faulting. On February 6, 2013 the largest under-thrusting earthquake (Mw 8.0) that has been instrumentally recorded in the region ruptured the megathrust. The epicenter (10.738°S, 165.138°E) is about 1° north of epicenters of prior large shallow under-thrusting events in Vanuatu in 1934 (M ~ 7.8) and 1966 (MS 7.9), and there is overlap of all three events' aftershock zones, but not their large-slip regions. At least 10 lives were lost, with 6 more missing, due to tsunami ~ 1.5 m high striking the town of Lata and several villages on the main Santa Cruz Island of Nendö (Ndeni) and a nearby small island Nibanga. Inundation of 500 m flooded the Lata airport. The tsunami was well-recorded by DART buoys spanning an unusually wide three-quadrant azimuthal aperture. Iterative modeling of teleseismic broadband P waves and the deep-water tsunami recordings resolves the slip distribution. There are two large-slip patches with a southeastward rupture expansion at about 1.5 km/s, with the second patch appearing to have ruptured with large slip at the trench. The event has relatively low short-period seismic wave energy release, but a typical overall moment-scaled total energy. The shallow rupture depth may be associated with the low level of short-period energy, and a near-total stress drop may account for a lack of underthrusting aftershocks among a highly productive aftershock sequence that included three events with M_w ≥ 7.0.

Item Type:Article
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URLURL TypeDescription
Lay, Thorne0000-0003-2360-4213
Ye, Lingling0000-0002-8739-2072
Kanamori, Hiroo0000-0001-8219-9428
Cheung, Kwok Fai0000-0002-7435-0500
Additional Information:© 2013 Elsevier B.V. Received 22 March 2013; Received in revised form 29 June 2013; Accepted 2 July 2013; Available online 12 July 2013. This work made use of GMT, SAC and Matlab software. The IRIS DMS data center was used to access the seismic data from Global Seismic Network and Federation of Digital Seismic Network stations. We thank an anonymous reviewer for constructive comments. DART buoy data were obtained from the NOAA National Data Buoy Center. This work was supported by NSF grants EAR-1245717 (T. L.).
Funding AgencyGrant Number
Subject Keywords:Great underthrusting earthquake; Vanuatu subduction zone; Tsunami on Santa Cruz Island; Shallow megathrust slip; Rupture modeling from seismic and tsunami waves; Southwest Pacific earthquake hazard
Record Number:CaltechAUTHORS:20140207-112339641
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Official Citation:Thorne Lay, Lingling Ye, Hiroo Kanamori, Yoshiki Yamazaki, Kwok Fai Cheung, Charles J. Ammon, The February 6, 2013 Mw 8.0 Santa Cruz Islands earthquake and tsunami, Tectonophysics, Volume 608, 26 November 2013, Pages 1109-1121, ISSN 0040-1951,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43724
Deposited By: Jason Perez
Deposited On:07 Feb 2014 23:29
Last Modified:10 Nov 2021 16:42

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