2016-05-17. Rumbling under the Volcanoes.

posted May 25, 2016, 1:09 PM by Alan Gould
By UC Berkeley Seismological Laboratory. For GSS Energy Flow chapter 2. Excerpt: First it was Mount St. Helens in Washington, now it is Mount Hood in Oregon. Recently, hundreds of small earthquakes have been detected under these two slumbering volcanoes. Is something ominous brewing in the Cascade Range this spring? Are we in for another catastrophic eruption similar to the one which obliterated a large part of Mount St. Helens exactly 36 years ago tomorrow? While no serious Earth scientist will ever rule out a surprise eruption completely, all experts dealing with volcanism in the Cascade Range do not see the recent earthquake swarms as a sign of imminent danger on either of the two fire mountains. In fact, monitoring seismicity is currently the most powerful tool in understanding the behavior of magma inside a volcanic edifice. ...Over the years, seismologists have detected many kinds of such magmatically driven earthquakes, the most common being the so-called "volcano tectonic" or VT-events. A detailed observation of such quakes can even be used to predict imminent eruptions in a reliable fashion. ...Luckily, none of the quakes in the current earthquakes swarms under the two Cascadian volcanoes were of that critical type....  http://seismo.berkeley.edu/blog/seismoblog.php/2016/05/17/rumbling-under-the-volcanoes