Mount Hood
About Mount Hood:
- Mount Hood is a Composite Volcano.
- It is Oregon's highest peak.
- Mount Hood is located 75 km southeast of Portland Oregon.
- The Volcano is also located in the Cascades Region. It is the fourth highest peak in the region.
- The volcano has been the site of about 15 earthquake swarms including one in January 1999.
- It is expected to erupt again.
Eruptive History of Mount Hood:
- Mount Hood is over 500,000 years old.
- It experienced decades to centuries of frequent eruptions separated by quietness lasting up to 10,000 years.
- The most significant eruptive periods were 1,500 years ago and 200 years ago.
- Mount Hood's history does not contain violent eruptions.
- The last significant eruption occurred in 1805.
Lava flows of about six to eight miles per hour built up Mount Hood's flanks sector by sector.
Mount Hood also has a history of lava dome collapse. Lava builds up over the volcano's vents and repeatedly crashes down creating pyroclastic flows. The heat creates lahars that flow down the river valleys. Over the past 30,000 years, lava dome collapse has characterized Mt. Hood's eruptive history.
Debris avalanches have also occurred. The largest of them have removed Mount Hood's summit and flanks of the volcano.
Mount Hood's
Big Events:
1st Event:
- This occurred about 100,000 years ago.
- A major section of the volcano's north flank and summit collapsed.
- A debris avalanche formed and a lahar formed off of that, which surged into the Hood River Valley.
- The lahar was 400 feet deep.
- Lava filled the area left by the avalanche.
2nd Event:
- This event occurred about 1,500 years ago on the south side of the volcano.
- A lahar was created and boulders eight feet in diameter were deposited
- This was a big event for Mount Hood, but only about 1/10 the size of the first event.
The Future of Mount Hood:
- Scientists expect the next eruption to produce pyroclastic flows and lahars.
- It is important to know the hazard zones and to be able to react properly to an eruption
Sources:
- http://pubs.usgs.gov/fs/2000/fs060-00/
- http://www.gonorthwest.com/Oregon/cascades/mt_hood/Mt_Hood.htm
- http://scienceblogs.com/eruptions/2009/04/24/volcano-profile-mt-hood/