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Weekly Volcano Watch: 12 March 2009

Posted by feww on March 12, 2009

Latest U.S. Volcano Alerts and Updates for Thursday, Mar 5, 2009 at 06:40:05 PST

  • 2009-03-11 20:27:47 Okmok Advisory Yellow
  • 2009-03-11 20:27:47 Redoubt Advisory Yellow
  • 2009-03-11 20:27:47 Cleveland Advisory Yellow
  • 2009-03-11 20:07:45 Kilauea Watch Orange
  • 2009-03-03 01:05:40 Mauna Loa Advisory Yellow

Volcano Hazards Program Webcams page links to webcams at 19 of the 169 active volcanoes in the U-S.

Volcanic Activity Report: 4 March – 10 March 2009

Source: SI / USGS Weekly Volcanic Activity Report

New activity/unrest:

VoW: Rainier


Mount Rainier, at 4392 m the highest peak in the Cascade Range, forms a dramatic backdrop to the Puget Sound region. Large Holocene mudflows from collapse of this massive, heavily glaciated andesitic volcano have reached as far as the Puget Sound lowlands. The present summit was constructed within a large crater breached to the north during the a mid-Holocene eruption as a result of the collapse of a once-higher edifice. Several postglacial tephras have been erupted from Mount Rainier; tree-ring dating places the last recognizable tephra deposit during the 19th century. The present-day summit cone was formed during a major mixed-magma explosive eruption about 2200 years ago and is capped by two overlapping craters. Extensive hydrothermal alteration of the upper portion of the volcano has contributed to its structural weakness; an active thermal system has caused periodic melting on flank glaciers and produced an elaborate system of steam caves in the summit icecap.
Photo by Lee Siebert, 1983 (Smithsonian Institution). Caption: GVP

  • Country: United States
  • Region: Washington
  • Volcano Type: Stratovolcano
  • Last Known Eruption: 1894
  • Summit Elevation: 4392 m (14,409 feet)
  • Latitude: 46.853°N (46°51’10″N)
  • Longitude: 121.760°W ( 121°45’37″W)

Seattle_Rainier
Mount Rainier photographed from Seattle, WA. Photo dated July 2005. Source. Image may be subject to copyright.

Monthly report (subject to change) from

06/1969 (CSLP 53-69) Increased seismicity since September 1968

“Local activity has been increasing each month for the last three months. We have been averaging about 1-3 ‘Mt. Ranier Events’ per 5-day period with an increase to about five per 5-day period last September 1968. This April, the events increased to approximately five per 5-day period. In May, it increased to about six per 5-day period and as of 15 June the increase is to approximately 12 per 5-day period.”

Information Contact: N. Rasmussen, Seismology Station, University of Washington.

Cascade Range Current Update

CASCADES VOLCANO OBSERVATORY WEEKLY UPDATE
Friday, March 6, 2009 09:05 PST (Friday, March 6, 2009 17:05 UTC)

Source: USGS/Cascades Volcano Observatory, Vancouver, Washington

Cascade Range Volcanoes
Volcano Alert Level: NORMAL
Aviation Color Code: GREEN

Activity Update: All volcanoes in the Cascade Range are at normal levels of background seismicity. These include Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams in Washington State; Mount Hood, Mount Jefferson, Three Sisters, Newberry Volcano, and Crater Lake, in Oregon; and Medicine Lake volcano, Mount Shasta, and Lassen Peak in northern California.
Mount St. Helens has been at Volcano Alert Level NORMAL (Aviation Color Code GREEN) since July 10, 2008.

Recent Observations: Activity at all Cascade volcanoes remained at background levels. A few tiny earthquakes were detected at Mount St. Helens and Mount Shasta.

The U.S. Geological Survey and University of Washington continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted.

Introduction

Mount Rainier at 4393 meters (14,410 feet) the highest peak in the Cascade Range is a dormant volcano whose load of glacier ice exceeds that of any other mountain in the conterminous United States. This tremendous mass of rock and ice, in combination with great topographic relief, poses a variety of geologic hazards, both during inevitable future eruptions and during the intervening periods of repose.

The volcano’s past behavior is the best guide to possible future hazards. The written history of Mount Rainier encompasses the period since about A.D. 1820, during which time one or two small eruptions, several small debris avalanches, and many small lahars (debris flows originating on a volcano) have occurred. This time interval is far too brief to serve as a basis for estimating the future behavior of a volcano that is several hundreds of thousands of years old. Fortunately, prehistoric deposits record the types, magnitudes, and frequencies of past events, and show which areas were affected by them. At Mount Rainier, as at other Cascade volcanoes, deposits produced since the latest ice age (approximately during the past 10,000 years) are well preserved. Studies of these deposits reveal that we should anticipate potential hazards from some phenomena that only occur during eruptions and from others that may occur without eruptive activity. Tephra falls, pyroclastic flows and pyroclastic surges, ballistic projectiles, and lava flows occur only during eruptions. Debris avalanches, lahars, and floods commonly accompany eruptions, but can also occur during dormant periods.

This report (1) explains the various types of hazardous geologic phenomena that could occur at Mount Rainier, (2) shows areas that are most likely to be affected by the different phenomena, (3) estimates the likelihood that the areas will be affected, and (4) recommends actions that can be taken to protect lives and property. It builds upon and revises a similar document prepared by D.R. Crandell in 1973. Our revision was motivated by the availability of new information about Mount Rainier’s geologic history, by advances in the field of volcanology, and by the need to assess hazards in a more quantitative manner than in Crandell’s pioneering report. —R.P. Hoblitt, J.S. Walder, C.L. Driedger, K.M. Scott, P.T. Pringle, and J.W. Vallance, 1998, Volcano Hazards from Mount Rainier, Washington, Revised 1998: U.S. Geological Survey Open-File Report 98-428

REPORT:
Volcano Hazards from Mount Rainier, Washington, Revised 1998

Mount Rainier at 4,393 meters (14,410 feet) the highest peak in the Cascade Range is a dormant volcano whose load of glacier ice exceeds that of any other mountain in the conterminous United States. This tremendous mass of rock and ice, in combination with great topographic relief, poses a variety of geologic hazards, both during inevitable future eruptions and during the intervening periods of repose. … This report (1) explains the various types of hazardous geologic phenomena that could occur at Mount Rainier, (2) shows areas that are most likely to be affected by the different phenomena, (3) estimates the likelihood that the areas will be affected, and (4) recommends actions that can be taken to protect lives and property. It builds upon and revises a similar document prepared by D.R. Crandell in 1973. Our revision was motivated by the availability of new information about Mount Rainier’s geologic history, by advances in the field of volcanology, and by the need to assess hazards in a more quantitative manner than in Crandell’s pioneering report. —Hoblitt, et.al., 1998

Ongoing Activity:

FEWW Forecast: Mount Rainier could erupt in the next 36 months with a probability of 0.65 [and in the next 18 months with a probability of >0.5]

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