Virgo Logbook

Environmental Monitoring (Environmental Monitoring)

fiori, hoak - 17:48 Tuesday 28 February 2017 (36700)

Sea microseism statistics

Attached plots show the percentile levels of CEB rms seismic noise velocity in the 0.1 - 1 Hz band monitoring the seismic activity associated to sea motion. The percentiles are computed over about 2 years of data (from Jan 2015 to Feb 2017).

Plot 1 refers to W motion, Plot 2 refers to N motion and Plot 3 refers to Vertical motion. For convenience, Plot 4 compares percentiles of W, N and V motion.

Figure 5 shows the rms noise during the past week. So, looking at Plot 4 we learn that last Friday and Saturday (24th and 25th) we experienced a sea microseism at the 94 PL, while today we are up to 98 PL (!)

Images attached to this report

Comments to this report:

fiori, hoak - 16:41 Wednesday 01 March 2017 (36718)

here attached are the text files with the microseism percentile data shown in this plot.

Non-image files attached to this comment

fiori, hoak - 11:32 Friday 03 March 2017 (36751)

for convenience, here attached are also the histogram data, as they appear in Fig.1. Also attached is the matlab file used to produce these histograms and their cumulative sums.

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Non-image files attached to this comment

travasso, fiori - 14:17 Thursday 27 July 2017 (38879)

Taking into account the percentiles described in the log-entry 36700, we set the alert values of the Environmental Flag "SeaActivity" in the DMS.

Using the bandwidth 0.1Hz-1Hz, the flag is set as below:

BRMS(ENV_CEB_SEIS_N_50Hz): YELLOW if the value is above the 75th percentile (1.25e-6), RED if the value is above the 90th percentile (1.98e-6)

BRMS(ENV_CEB_SEIS_W_50Hz): YELLOW if the value is above the 75th percentile (1.52e-6), RED if the value is above the 90th percentile (2.46e-6)

BRMS(ENV_CEB_SEIS_V_50Hz): YELLOW if the value is above the 75th percentile (0.56e-6), RED if the value is above the 90th percentile (0.86e-6)