Results from the Quake-Catcher Network Rapid Aftershock Mobilization Program (QCN-RAMP) Following the M8.8 Maule, Chile Earthquake

Following the 27 February 2010 M8.8 earthquake in Maule, Chile we initiated a QCN Rapid Aftershock Mobilization Program (RAMP). We had an overwhelming number of people eager to participate in the RAMP and rapidly installed 100 USB sensors to record aftershocks. The USB accelerators were deployed in regions directly affected by the mainshock and were densely concentrated in the Bío-Bío region of Chile. Trigger metadata was transferred in real-time and waveform data were recorded continuously at 50 samples per second. Most trigger metadata was received at the QCN server within 7 seconds and waveform data was uploaded in 10 minute-long segments. Using the aftershock trigger data, we refined our triggering and event detection algorithms and retrospectively tested whether the network can rapidly and accurately identify the location and magnitude of moderate to large aftershocks (M>4). We are also currently expanding our network in many locations around the world, including Southern California. Because of our low-cost, easy to install sensors, we can quickly deploy a densely distributed network of relatively inexpensive seismic stations throughout a region. We also examine whether the data collected by low-cost USB accelerometers can be used to estimate local site response, which is the amplification of ground motion caused by local site conditions. Site response can be used to predict structural damage, with greater damage found in areas of high site amplification. As observed in previous large earthquakes, as well as during the 2010 M8.8 Maule, Chile earthquake, areas of intense structural damage are spatially limited so it is important to have dense seismic instrumentation to better predict highly localized site response. To estimate site response, we use data from large aftershocks recorded on QCN sensors in the Bío-Bío region of Chile. We compare the S-waves and coda-wave spectral ratio methods to determine relative site amplification effects. These results suggest that, with high station densities, QCN sensors can provide detailed maps of local site conditions for use in seismic hazard analysis. Our preliminary results from the data collected from QCN stations around the world suggest that MEMS sensors installed in homes, schools, and offices provide a way to dramatically increase the density of strong motion observations for use in seismic hazard analysis, source rupture imaging, and earthquake early warning.