gPhone Gravity Meters Measure Anomalous Seismic Noise

There appears to be an increase in the average background seismic noise observed with gPhone gravity meters in Colorado, Minnesota, and Sidney, BC (near Vancouver, BC) for about one month from November 16, 2008 through December 16, 2008. As shown below in Figure 1, the background noise envelopes are almost identical for the gPhones located in Minnesota (SN#51) and Colorado (SN#69). The noise envelope for the gPhone located in Vancouver (#55), is also highly correlated but there are some notable differences. While it is normal to see increased seismic noise during this time, it appears that this period may be anomalous in sustained noise amplitude.

We also present results from different gPhones under test in Colorado from September 2006 through January 2009 that clearly show seasonal variations in the background noise level. Shown below in Figure 2 is data from meters in June 2007, and Figure 3 shows data from November 2007. Note the increase in amplitude.

For a complete discussion, please click here for a report in pdf format.

Also, please see related articles on earthquake monitoring with gPhones (pdf), gPhone Corrleation, the Sichuan Earthquake of 2008, and the Kurile Island Earthquakes of 2006.