Orting Geotechnical College Proposal Project No-Nova Geotechnical Assessment Firm Anthony, Geri, Reyn & Marie
About Orting, WA - Seattle-Tacoma-Bellevue Metropolitan area; 48km from Mt. Rainier - Town sits in a fertile valley between two major rivers, the Carbon and Puyallup Rivers - Town is built atop a 500 year old mudflow that buried the valley 9m deep - Lahar or mudflow is the most serious hazard, approximately 500 years since a large mudflow came through the valley; could erupt anytime within 300 year window - 42 minutes to get to high ground --- 80 feet above the valley floor - sirens will alert 4400 residents that have less than 45 minutes to evacuate
MAP OF ORTING, WA Mt. Rainier
CASCADIA SUBDUCTION ZONE ● The fault line between the North American plate and the Juan de Fuca plate ● Heavier (more dense) Juan de Fuca plate is subducting underneath the SW-moving NA plate ● The subduction process has created massive earthquakes and volcanic eruptions (including the 1700 Cascadia earthquake & the Mt. St. Helens volcanic eruption in 1980)
Volcanic History - Mount Rainier - Highest peak in the Cascade range (4392m) - First major eruption 5600 years ago - Ensuing eruptions built up the summit
Eruption History - 1500 yrs ago ; Ash eruption, no lava - 1100 - 1000 yrs ago ; (Frying Pan Creek eruptive period) - Major Lahar production - 500 yrs ago (Electron mud flow) - No evidence of eruption, however major Lahar movement was observed - Steam explosions?
Mount Rainier (structure) - Large lahars (Volcanic Mudflows) from the eruption reach Puget Sound lowlands - Hydrothermal alteration of upper portion of volcano causes structural weakness ; promotes collapse - Numerous steam caves beneath ice cap
NVEWS - High threat potential - National Volcano Early Warning System - Proposed; Mt Rainier is a top priority
Risky Business
We Have a Plan!
Our Development Vision
Suggested Location - At the fork of Highway 162 and the Carbon River - Advantages - Accessible by transit and not too distant (approx 5.5 km) - 30m elevation higher than Orting - Proximity to river allows for study of Lahar in the riverbed - Proximity to mountain for hiking trips and studies
Risks -Proximity to Mountain -Distance from Town; potential to be cut off in case of emergency -Closeness to River - Lahar will naturally follow the river
Minimizing Risk - Helicopter Landing Base - NVEWS (National Volcano Early Warning System)
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