The USGS is requesting volunteers in the greater Walnut Creek/Pleasant Hill/Concord area to consider hosting a temporary seismic station for a period of two to three years for the purpose of studying site response in this part of the Bay area. All participation is strictly voluntary. The figure below shows the research area from the East Bay Hills on the west, across the urban valley up to the hills east of Clayton on the east.

The benefits of hosting such a station, in addition to knowing that one has contributed to the understanding of earthquake ground motion hazard in their home town, include bi-annual meetings with the scientists that come through the area to collect the data. During these visits, USGS staff will show you the earthquakes recorded on the seismometer installed on your property. If you are potentially interested in hosting a station, scientists will be in the area and available to visit with you at your home and answer any questions you might have before you make a final decision. The planned date for the installation of the new array is March 2017. The USGS has been using urban arrays to study site response in the Bay area since 1999.

Instrumentation

The type of sensor used in this study is the K2 seismograph. The K2 is an accelerometer and data-logger combined into a single, portable package. The unit is the size of a large shoe box. It is usually installed in a corner of the garage or a convenient area on a patio or side walk along the house. A photo of a unit installed in a garage is shown below:

The systems are installed on concrete anchored with epoxy. They are powered by battery but do have a charging system that uses about 3 watts of power or 50 cents per month of electricity. A separate GPS device is installed in order to correctly time stamp the recorded earthquake signals. This is accomplished by running a coaxial cable along the rafters of a garage or along an external house corner to a height that enables the GPS receiver to obtain signals from the necessary satellites.

For more information on participation in this study please contact Alena Leeds (aleeds@usgs.gov or 303-887-8743).