Orting Geotechnical College Proposal Project No-Nova Geotechnical - - PowerPoint PPT Presentation

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)