Community Seismic Network
A low-cost dense seismic network

JPL

2017 CSN@JPL 94 structures instrumented

Map of NASA-JPL campus in Pasadena, CA showing locations of CSN accelerometer deployments. Horizontal dimensions are approximately 1 km by 1 km.

Our NASA-JPL partner comprises a 1 km x 1 km campus representing a mini-city prototype "sandbox" in which to operate our ground-building network, and to test the integrated city-scale 4D monitoring network through refinement of algorithms. It serves as our well-instrumented mini-city testbed because one or multiple CSN accelerometers are installed at each of the approximately 100 buildings on the JPL campus. The campus is home to a variety of building types. Of the total 220 stations deployed at JPL, 100 are ground-level stations contributing maximum shaking pick data to the experimental ShakeMap. The remaining 120 stations are deployed on upper floors of buildings that have up to 9 floors.

JPL sits at the southern foothills of the San Gabriel Mountains, and next to faults north of campus. Microzonation—the mapping of variations in seismic response amplification of the ground occurs—over the JPL campus as shown by local earthquakes recorded by the CSN sensors distributed around campus. For example, the 7/25/2015 M4.2 Fontana earthquake indicated amplification at JPL sites adjacent to the foothills. These sites may have experienced a basin-edge effect in which the geometry and impedance contrast between the sedimentary basin to the south and hard rock mountains to the north, affected the campus response on a length scale of 10-100 meters.

JPL building types include wood frame, reinforced concrete, steel-moment frame, steel sheds and modular trailers. Each of these structures has a canonical fragility curve associated with it based on a building classification supplied by FEMA's natural hazard analysis HAZUS software. A web instance of the CSN-fragility analysis has been constructed for a 9-story building on campus.

NASA-JPL CSN-Fragility instance showing assessed fragilities in select buildings due to a scenario M6.9 Verdugo fault earthquake near the JPL campus.