Quake, Steam Explosion Shake Mount St. Helens
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Quake, Steam Explosion Shake Mount St. Helens
Quake, Steam Explosion Shake Mount St. Helens.
Geologist John S. Pallister was flying over Mount St. Helens when he spotted something unusual.
Pallister, a private pilot who works in the hazards section of the U.S. Geological Survey's Cascades Volcano Observatory, noticed a line of steam coming from a zipper-like fracture line atop the growing lava dome in the crater of the southwest Washington volcano.
"It was interesting enough to take some pictures," Pallister told The Columbian newspaper of the Sunday flight.
After landing, he learned that a 2.9-magnitude earthquake had registered on seismographs at the observatory in Vancouver. That was followed by a small tremor that lasted nearly an hour and a half, an unusually long period, punctuated by a second quake of 2.7 magnitude — all in the same period in which he saw the steam.
Along with the shake, rattle and roll, tiltmeters registered alternate ground swelling and deflation near the lava dome, which has been growing in the crater since the fall of 2004.
All are typical signs that magma, superheated gases or both are moving through conduits beneath St. Helens, which blew its top with devastating force on May 18, 1980, leveling 230 square miles of forest and killing 57 people.
The last noteworthy tremor at the volcano lasted 55 minutes on Oct. 2, 2004, and was much more powerful, registering on seismometers from Bend, Ore., to Bellingham and causing a hasty evacuation of the Johnston Ridge Observatory five miles north of the crater.
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©FOXnews
Foto ©USGS (archief) | Gewijzigd: 20 januari 2008, 13:58 uur, door Pgs3000
Geologist John S. Pallister was flying over Mount St. Helens when he spotted something unusual.
Pallister, a private pilot who works in the hazards section of the U.S. Geological Survey's Cascades Volcano Observatory, noticed a line of steam coming from a zipper-like fracture line atop the growing lava dome in the crater of the southwest Washington volcano.
"It was interesting enough to take some pictures," Pallister told The Columbian newspaper of the Sunday flight.
After landing, he learned that a 2.9-magnitude earthquake had registered on seismographs at the observatory in Vancouver. That was followed by a small tremor that lasted nearly an hour and a half, an unusually long period, punctuated by a second quake of 2.7 magnitude — all in the same period in which he saw the steam.
Along with the shake, rattle and roll, tiltmeters registered alternate ground swelling and deflation near the lava dome, which has been growing in the crater since the fall of 2004.
All are typical signs that magma, superheated gases or both are moving through conduits beneath St. Helens, which blew its top with devastating force on May 18, 1980, leveling 230 square miles of forest and killing 57 people.
The last noteworthy tremor at the volcano lasted 55 minutes on Oct. 2, 2004, and was much more powerful, registering on seismometers from Bend, Ore., to Bellingham and causing a hasty evacuation of the Johnston Ridge Observatory five miles north of the crater.
Klik hier voor het hele artikel
©FOXnews
Foto ©USGS (archief) | Gewijzigd: 20 januari 2008, 13:58 uur, door Pgs3000
