Orting Community College Proposal Cedric, Celina, Francine, Sarah, Samuel GEO CORP
Located in Washington, 42 miles south of Seattle. Situated between two rivers on fertile plains. Built on lahar deposits. The most at risk from Mount Rainier eruptions.
Cascade Volcanoes Subduction is caused by the convergent Juan de Fuca and North American plates Juan de Fuca plate is forced below the other causing melting of the plate and creating an increase in magma volume, can be sudden and violent. Plates are stuck on points of friction, and when the friction reaches a point that the plates quickly slip under this causes a fast increase in the displaced volume of magma, which can be displaced upwards and forced through the mountain range which has developed due to the constant pressure on the North American plate. This sudden movement will more importantly cause a massive earthquake in the region, could exceed a magnitude 9.0. The Cascade range extends from the BC coastal mountains, to Northern California along the fault between the plates and includes major cities such as Portland, Seattle, and Vancouver.
Mt. Rainier History grew on top of remains of an older Mt. Rainier that was active 1-2 million years ago stages of high and modest lava output, currently in a modest period Development 500 to 420 ka beginning of Mt. Rainier, volcano very active 420 to 280 ka small and infrequent activity, reduced lava accumulation 280 to 160 ka eruption rates increased, volcano grew to highest height 160 to 40 ka eruptions reduce, increase of erosion 40 to 15 ka increased eruptions, mountain grew
Late-Holocene Summary of late-holocene Mount Rainier eruptions Red circles show eruptions with direct physical evidence Orange circles represent possible eruptions by uniform plast type in White River confluence lahar Light blue circles represent a lack of physical evidence There are other historically reported eruptions but they lack any physical evidence
Hazards of building near Mt. Rainier Because of its elevation (4,392 m), relief, hydrothermal alteration, icecap, glacier-fed radial valleys, and proximity to encroaching suburbs of the Seattle-Tacoma metropolis, Mount Rainier is the most threatening volcano in the Cascades. Eruption at any time: could produce volcanic ash, lava flows, and avalanches of intensely hot rock and volcanic gases, called pyroclastic flows. Some of these events swiftly melt snow and ice and could produce torrents of meltwater that pick up loose rock and become rapidly flowing slurries of mud and boulders known as lahars. Lahars: triggered by sector collapse or magma- water-ice interaction rather than from an eruption itself. When Mount Rainier erupts it will have devastating results. With Rainier being the largest volcano in the Cascades and located near large cities there is great potential for destruction. The potential hazards can be known by using Mt. St. Helens as an example and the stratigraphy of the surrounding landscape.
Hazards cont. Hazards include floods, lahars, landslides, pyroclastic flows, lava flows, and tephra fallout. These hazards can not only destroy an area, but also effect water quality and other health risks in places that survive.** Some hazards are not associated with eruption. Avalanches, landslides, floods, and lahars can be caused by any of the volcano's thirty earthquakes that occur each year. Avalanches happen frequently and are caused by melting glaciers, landslides and rock falls also occur regularly Floods and lahars can occur at any time. These can start by the steam escaping from the mountain and melting some of the nearly 4.5 billion cubic meters of snow and ice locked up in glaciers. (Mount Rainier has more snow and ice than any other mountain in the lower 48 states.) The greatest threat from Mount Rainier comes from the lahars. A lahar is a large mudflow that looks and acts like wet concrete and travels down river valleys at speeds of up to 60 mph. Due to the great steepness of Mount Rainier, lahars would travel further than the Mt. St. Helens lahars.
Risks to town of Orting Probability of volcanic eruption is 1 in 250,000 years (skewed b/c of other variables they can t assess) Preparedness for volcanic eruption education the community, tips on kits, radio broadcast in place Orting can be prepared for a volcanic eruption It is very possible to mitigate the consequences of a volcanic eruption Already prepared for other disasters, evacuation route and map ready
Geo Corp Recommendation Our team tentatively recommends that Orting goes ahead and builds the community college While there are risks we believe they can be mediated by preparedness and education We also suggest building further away from the river bank to avoid certain hazards However, we strongly suggest that this community works with Geo Corp to continue assessing the risks and hazards of building in Orting
Thank you for your consideration! GEO CORP