22 September 2009

Rumblings on Rainier??

Posted by Dan Satterfield

Recent quake map around Mount Ranier in Washington.

Recent quake map around Mount Ranier in Washington.

I did a geological field trip to the Pacific Northwest in 2006. It was two fabulous weeks and I got some great snaps of beautiful Mount Rainier. This past Summer, while at the American Meteorological Conference in Portland, I returned to Mount Saint Helen’s as well.

When St. Helen’s exploded in May 1980, the volcanic dust was tracked on satellite imagery across the country. I had only been doing weather on TV for a few months, and I remember putting volcanic ash in the forecast in Oklahoma City! I said at the time, that it would likely be the first and last time in my entire career that I put that into a forecast.

29 years later, it still is.

The next morning a thin gray dust covered my bicycle seat in Norman, Oklahoma.

I have always been keenly interested in Geology, and my first summer job at OU, was at a seismological observatory run by the University near Tulsa. Watching the drums slowly rotate with occasional wild jumps of the needles was the fun part of the job.

My boss could always tell when I was arriving for work because the seismograph would wiggle as my station wagon crossed railroad tracks at the bottom of the mountain!

Mount Rainier is one gorgeous mountain. Dan's Photo 2006.

Mount Rainier is one gorgeous mountain. Dan's Photo 2006.

Looking at some of the blogs written by Geologists this evening I ran across something interesting on ERUPTIONS, written by Erik Klemetti. He spends most of his time thinking about magma. I don’t doubt it! It’s a fascinating subject!

He mentions that there has been an increase recently in quakes at the heavily monitored Mount Rainier. Nothing to panic about here, but it’s wise to remember that St. Helen’s was a reminder that the Northwest has several volcanoes, and they are not likely dead. If a Saint Helen’s event were to happen at Rainier today, the damage and disruption would be an order of magnitude higher than 30 years ago. Many more people live nearby now.

mt st helens lahar usgsThe USGS rates Rainier as the most dangerous of the NW volcanoes because of the high population nearby and the large amount of snow and ice on it’s slopes. A LAHAR is a big threat from Rainier. They are a deadly flow of mud, ash, rock and water. The water usually comes from melting snow, caused by an eruption. Raineier has A LOT of snow. These events can cause great loss of life.

A paper published in 1987 estimated that 270 cubic kilometers of lava has erupted from the mountain, over the last one million years! (USGS) This is a short nap in Geological time.

Geologists, and Seismologists are as fanatical about their work as we Meteorologists, so if you live in the Northwestern USA, you can be assured that very bright people are watching the multitude of sensors around Rainier. The Cascade Volcano Observatory has an excellent site with loads of good info.