Low-cost micro-electro-mechanical systems (MEMS) accelerometers have improved rapidly allowing for very dense seismic arrays. The Quake-Catcher Network (QCN) makes use of MEMS-based tri-axial sensors installed in homes and businesses to record earthquakes, with 3000 participants worldwide. We compare the instrumental sensitivity between traditional and MEMS-based sensors by conducting shake table tests of five different types of MEMS sensors. Overall, sensors performed to expectations. We also compare seismograms recorded following the 3 September 2010 Mw7.1 Darfield earthquake by 192 QCN stations that were installed in a dense array to record the on-going aftershock sequence in and around the city of Christchurch. The peak ground accelerations (PGA) recorded during a M5.1 aftershock are spatially variable, but show a clear decay in amplitude with distance. In general, closely located GeoNet and QCN stations report similar PGA. Finally, data are used to test the real-time rapid earthquake detection scheme. We find the network can provide reasonable estimates of the earthquake location and magnitude within 8-12 seconds, on average.

Acknoweldgements: Work presented here is supported by the National Science Foundation.

For further reading: Cochran, E.S., J.F. Lawrence, A. Kaiser, B. Fry, A. Chung, C. Christensen, Comparison between low-cost and traditional MEMS accelerometers: a case study from the M7.1 Darfield, New Zealand aftershock deployment, Annals of Geophysics, 54(6), 728-732, 2011. doi: 10.4401/ag-5268

Keywords: rapid_earthquake_detection, seismic_instrumentation, large_n_networks