Structural health monitoring through dense instrumentation by community participants: the Community Seismic Network and Quake-Catcher Network

The Community Seismic Network and Quake-Catcher Network involve participants from communities at large to install low-cost accelerometers in houses and buildings for assessment of shaking intensity due to earthquakes. The seismometers are designed for two types of connec-tions: a USB-connected device which connects to the host’s computer, and a stand-alone sensor-plug-computer device that directly connects to the internet. The three-component sensors report both continuous data and amplitude anomalies in local acceleration to a Cloud computing service consisting of data centers geographically distributed across the continent, or to a distributed computing system. The continuous time series waveform data are being used to evaluate response parameters such as peak acceleration, peak velocity, and inter-story drift values. In addition, modal properties such as fundamental and higher mode frequencies and mode shapes are being computed from small and moderate earthquake data from the building. Building motion is computed for every floor of the building using only earthquake records from a single floor. Visualization models that map the instrumented buildings’ responses have been construct-ed using SketchUp and an associated plug-in to Matlab with recorded shaking data. This data visualization approach is different from other techniques because each building model is customized to show actual data recorded from that building on varying spatial scales, without the need for large-scale parallel computing facilities or complicated software that requires a steep learning curve