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Exploring the suitability of the Quake-Catcher Network in the USGS ShakeMap: Case studies from aftershocks of the 2010-2011 Darfield and Christchurch, New Zealand earthquakes

Liam J. Shaughnessy, Danielle F. Sumy, Elizabeth S. Cochran, Corrie J. Neighbors, & Robert-Michael de Groot

Published August 15, 2016, SCEC Contribution #6843, 2016 SCEC Annual Meeting Poster #231

Following the September 3, 2010, MW 7.1 Darfield, New Zealand earthquake, the Quake-Catcher Network (QCN; quakecatcher.net) team rapidly deployed 192 low-cost seismic sensors around Christchurch. These CodeMercenaries JoyWarrior JWF14F8 14-bit three-component Class C accelerometers monitored and recorded aftershocks of the Darfield earthquake, which included the February 21, 2011 MW 6.3 Christchurch event. In terms of performance, QCN sensor tests suggest these data are potentially useful for ground-motion studies, which could include ShakeMap [Evans et al., 2014]. Previously, the Mexican Red Atrapa Sismos network team illustrated that ground-motion results from a dense array of QCN sensors in Mexico can be used to produce accurate intensity ShakeMaps for a MW5.9 and MW7.2 earthquake, respectively [Dominguez et al., 2015]. Therefore, the purpose of the present study is to conduct a feasibility test to show if aftershock data collected by QCN sensors deployed in the epicentral region of the 2010-2011 Darfield and Christchurch earthquakes are suitable for integration into the USGS ShakeMap software and produce useful results. We compare the residuals between our ground-motion results with distance as compared to the Bradley [2013] ground-motion prediction equation for both QCN and traditional GeoNet strong-motion data, and find that the QCN accelerometers provide on-scale data suitable for use in ShakeMap. We examine ShakeMaps composed of QCN and GeoNet data individually and combined, and investigate the ground-motion residuals between the maps for the sake of comparison. Cochran et al. [2011] found that peak ground velocity and acceleration data and pseudo-spectral accelerations (PSA) measured by QCN are comparable to those measured by the GeoNet stations, thus we expect that the individual QCN and GeoNet ShakeMaps will look very similar. In addition, Kaiser et al. [2011] concluded that the dense QCN array in Christchurch provides comparable estimates of ground-motion and site response as the nearby GeoNet stations, and that QCN sensors can be useful in microzonation studies. We therefore conclude that QCN accelerometers provide a cost-efficient method to obtain accurate ground motion data for use in ShakeMaps. In areas of low station density, where traditional networks are limited, QCN sensors can increase local station density and provide higher-resolution mapping of ground-motion across urban areas that may help to inform earthquake response.

Key Words
QCN, Quake Catcher Network

Shaughnessy, L. J., Sumy, D. F., Cochran, E. S., Neighbors, C. J., & de Groot, R. (2016, 08). Exploring the suitability of the Quake-Catcher Network in the USGS ShakeMap: Case studies from aftershocks of the 2010-2011 Darfield and Christchurch, New Zealand earthquakes. Poster Presentation at 2016 SCEC Annual Meeting.

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