Posted by: magmatist | March 2, 2010

Updates to MBVRC News webpage

News at the Mount Baker Volcano Research Center News and Research webpage:

Nikki Moore’s thesis defense, March 12th

Second seismometer installed to monitor Mount Baker

Understanding the seismometer data

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Nikki Moore’s Mount Baker geochemistry thesis defense

Nikki looks for evidence of magma mingling at Park Butte.

WWU Geology masters candidate Nikki Moore will present a public defense of her thesis research March 12th, 2010 at 4:00 p.m. in ES 100 (the building Geology is in). The title is “Origin and geochemical evolution of mafic magmas from Mt. Baker in the northern Cascade arc, Washington: probes into mantle and crustal processes.”

Nikki’s advisor is Dr. Sue DeBari. Nikki has been working hard on this project, sampling basalt and basaltic andesite lavas at Mount Baker for three years. Everyone is invited to attend.

Second seismometer installed at Mount Baker

The Pacific Northwest Seismic Network (PNSN) has installed a second seismometer on the northeast flank of Mount Baker. The new broad band station, coded SHUK, augments the older MBW, on the west flank of the volcano. Two seismometers should help locate earthquake foci beneath the volcano more precisely, as well as other seismic activity elsewhere in the region. Although still under-monitored, this is an improvement; funding comes from an infusion of Federal money into USGS and associated volcano monitoring programs, such as University of Washington’s PNSN. Wes Thelen, of PNSN, says that “we want to up the amount of monitoring before they erupt so that we’re not sent scrambling when they do actually do start up”.

SHUK is located near the Mount Baker Ski Area. “The installation could not have been accomplished without the assistance and continuing support of the Mount Baker Ski Area”, Wes Thelen said. Data are available to the public by going here for webicorder data of all volcano seismometers in the Cascade arc. Choose the station you are interested in to see the data for a particular 12 hour period. Or, enter SHUK (or any seismometer code identifier) in the search box on this page to see data. There are now 20 seismometers on the US side of the arc. In addition to the 2 on Baker, Rainier and Mount Saint Helens are now well covered; there is one on Glacier Peak and others on Hood, Adams, Three Sisters, and Crater Lake.

For information on volcano monitoring methods in general, the Geological Survey of Canada has a nice synopsis here. However, there are no seismometers on the flanks of any of the several potentially active volcanoes in Canada.

Understanding data in the ‘latest earthquakes’ table for Mount Baker

Several visitors to the MBVRC website have asked about data on the Baker seismology data table to which we have a link on the links page. In particular, the meaning of the code in the column labeled ‘QUAL’ was not understood. Wes Thelen, at PNSN, explains: “The QUAL simply assigns two different parts of the location solution to letters between A and D.  The first is a measure of the earthquake location residuals.  You can think of it as the errors between the actual phase picks and the expected phase picks.  The second letter is a measure of the station distribution around the earthquake.  This often can’t be changed by just changing the phase picks.  Of course neither quality measure is purely independent of the other, but it provides a quick check of the overall quality of the location.  For research purposes, we usually only consider AA, BB, or BA events to be good.  We don’t like to publish things worse than a CC.  Unfortunately at Baker, the station configuration means that most events will have a C or D in the second quality metric.  Hopefully, the addition of SHUK will improve that.”

Of the most recent 20 earthquakes recorded at Baker (as of January 10, 2010, the most recent update), only two (August 2, 2009) and the most recent (January 9, 2010) have location and magnitude data even approaching the research quality events Wes talks about (each is BC in’quality’). In contrast, visit the tables for Saint Helens and Rainier to see the difference in QUAL that result from more seismometers. With time, we should see improvement in this as SHUK comes in to play.

Also note that the PNSN tables now remind us that earthquake data is only updated when there is a new earthquake tracked by one of the seismometers.

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