Counting tiny earthquakes at Rattlesnake Ridge

These figures are automatically updated hourly. Times are in UTC. Note: UGAP2 had battery power problems for a few days starting on Julian day 36 (Feb 5), hence the gap in some measurements.

Bottom panel: power at UGAP2 (EHZ component) at two different frequencies. The dirunal pattern, prominent at 8Hz (blue), follows traffic patterns- seismic noise significantly lowers at around 02:00 UTC/6pm PST each day. Weekends also tend to show slightly lower noise levels. This highly variable background noise level affects our ability to measure tiny earthquakes from the landslide mass creaking and cracking. If we want a time history of earthquakes that minimizes the bias from traffic, we are limited to only count those events that would be large enough to exceed the typical background noise level during peak traffic.

Middle panel: Number of high frequency earthquakes measured at the different stations. Earthuqakes are detected using a short term average/long term average function using 0.25/2.5 sec and must have an STA/LTA ratio of 3 and the amplitude in the 17-45Hz band must exceed 1 micrometer/sec.
Notes: The thresholds for UGAP5 and UGAP6 are higher than UGAP2 and UGAP3 to prevent saturation due to the higher rates of activity near those stations. All stations have not been operational all the time. UGAP5 and UGAP6 were not installed until Jan. 23, 2018. UGAP2 was removed for use elsewhere on Aug 4, 2018. UGAP5 lost signal from its seismometer on Jun 28 and was repaired on Aug 4, 2018.

Top panel: Number of concurrent peaks/spikes in the STA/LTA function (i.e. earthqukes) at either UGAP2 & UGAP3 (blue) or UGAP 3, 5 & 6 (red), which is our way to only count spikes seen at multiple stations within a narrow time window. This (hopefully) helps us to not be biased by a single noisey station which may happen when people are stomping around nearby. Spikes must be within two seconds of each other to be counted.

UPDATE Sep 28, 2018: UGAP6 started having problems in early Sep 2018. Beginning at Sep 1, the plots of common spikes labeled UGAP3/5/6 will actually be displaying spikes common to only UGAP3 and UGAP5, i.e. UGAP6 is removed from the calculations.

The last 14 days:
Last 10 days of tiny earthquakes

Since installation on Jan 3, 2018:
Full time history of tiny earthquakes