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.
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.