Posted by: magmatist | July 11, 2011

Two small ‘quakes in the same place, east flank of Baker

Two small earthquakes have been recorded at nearly the same place 7.5 km (4.65 mi) SE of Mount Baker’s summit. They occurred beneath the valley of Boulder Creek 4.2 km (2.6 mi) NW of the Baker Road bridge across the creek. Both of these little shakers were low frequency events. They are likely not significant volcano-wise, but it will be interesting to see if there are any more.

The target marks the epicenter of the two little earthquakes. Click to enlarge.

The first one was on July 9 at 11/07/09 10:02:45 UTC time, the location is  48.74N 121.73W, the depth is calculated to be 2.3 km and the magnitude was 1.7.
The webicorder seismograph for this ‘quake recorded at the SHUK seismometer (near the ‘Mount Baker’ ski area). http://www.pnsn.org/WEBICORDER/VOLC/SHUK_SHZ_UW_–.2011070900.html . It is the little black squiggle near the bottom, at 03:02:50 using PDT time scale on the right. If you click on ‘MBW’ on the menu above the trace you’ll see that instrument to the west of the volcano was apparently on the fritz, as it recorded no data (not sure what the big black squiggles are at 23:40 hours PDT on the 8th- something happened to the instrument or the data transmission).  Note that the location and date on the PNSN list for Mount Baker earthquakes is in UTC (London Time), which is listed on the right side of the  webicorder records (PDT = UTC -7 hours).

The second was the next day, 11/07/10 16:25:46 UTC time, same lat/long but much deeper, 7.9 km. The magnitude was 1.9. The webicorder record for this one at SHUK is here: http://www.pnsn.org/WEBICORDER/VOLC/SHUK_SHZ_UW_–.2011071012.html ; click on MBW and you’ll see it is still acting up, and continues to not record data right up until now. Hopefully this instrument will be up and running again soon.

A plot of recent earthquake epicenters in the Baker area is available here: http://www.pnsn.org/BAKER/bakerrec_eqs.html. You can access this site anytime by going to the MBVRC mainpage, http://mbvrc.wwu.edu/index.shtml, click on ‘links and webcams’ on the left hand menu, then find Pacific Northwest Seismic Network on the link list. Scroll down to ‘Latest earthquakes at Mount Baker’.

Dave Tucker


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