Major fault found from Mount Hood to Cascade Locks

September 3, 2011

If you feel uncomfortable about passing through the full-body scanners at the airport, what you read next may cause you to squirm.

Hood River is the first county in the state of Oregon to be scanned in its entirety with cutting edge technology known as LIDAR - right down to its geologic "skivvies."

And, what scientists uncovered is not necessarily pretty.

Nestled amidst a network of small earthquake faults surrounding Mount Hood, the geologic mapping program team discovered a significant fault oriented between Mount Hood and Cascade Locks, approximately 10 miles west of Parkdale.

The Blue Ridge fault, as it has been named, "is significant enough that it could produce an earthquake as large as a magnitude 7. That is a number that catches geologists' eyes," said Ian Madin, chief scientist with the Oregon Department of Geology and Mineral Industries and leader of the multi-agency team conducting the work.

"A quake at that level causes significant damage," Madin said. "That is the reason we are investigating this so thoroughly."

To answer further questions about the fault and better determine its risk level and activity, Madin's team will begin digging an investigative trench along one of the fault's sections on Sept. 12, Dollar Fire permitting.

"We were to have begun next week, but the dig site is within the fire closure area," said Madin. The trench will be placed in an existing clear cut area and refilled following data collection.

"We will examine soil strata to see if fault lines cut across geologic layers, indicating one single large earthquake or multiple small ones."

The data will allow the team to adjust the magnitude 7 risk estimate either up or down, depending on what they learn.

According to Madin, the fault is at least 8 miles long, oriented northwest to southeast, and is 10-15 miles deep. At most points, you can stand with feet on either side of the fault line.

Where the fault's potential danger is perhaps more evident, can be found in the scarps (ground-level cliffs) that are left behind - results of previous fault slippage. The Blue Ridge fault has multiple evident scarps that can span 20-30 feet in width.

The fault's north end appears to terminate about 20 miles from Cascade Locks and Bonneville Dam.

"What matters most in terms of potential damage is where the epicenter of the fault lies," said Madin. The closer to the epicenter, the greater potential hazard.

For now, with additional Blue Ridge fault information due to be updated and detailed, Madin shared some advice to residents.

"Anyone living in western Oregon should be aware that we live in a seismically active region. Everyone should be taking sensible precautions. Do what you can do to prepare at home and in your workplace - and then get on with your life."

Some of those sensible precautions include securing heavy furniture and objects to structures, anchoring chimneys and foundations, maintaining home and work evacuation plans and keeping a family disaster kit. More details are available through the Red Cross.

The fault discovery is part of a larger project however whose results will become public within the next month.

"We have already completed a thorough assessment of volcanic, landslide, flood and earthquake hazard zones for the entire Hood River Valley," said Madin.

Using LIDAR (light detection and ranging) - a high-tech laser-based imaging technology cousin of RADAR - Madin's team began aerial fly-overs in 2007 to collect the finely detailed images, allowing scientists to accurately evaluate the geologic composition and evolution of the Valley.

In addition to providing accessible land hazard information, data from the project will be used to help locate water-bearing rock and improve future construction siting, among other applications.

To view a current interactive map of LIDAR images for Oregon, detailed down to the street level, visit www.oregongeology.org/dogamilidarviewer/

Comprehensive Hood River Valley maps will be available soon online in an interactive format that will allow government agencies and residents alike to view detailed geologic hazard assessments for every Valley property.

Lot by lot and home by home, viewers may see recorded volcanic eruption, flood, earthquake and landslide risk assessments. The final interactive hazard maps, once completed and reviewed, will be posted at: www.oregongeology.org.

Hood River County is working in cooperation with Madin to incorporate collected data points when possible, into its existing Webmap Online Parcel Viewer program available through the County's website: www.co.hood-river.or.us, tabbed under maps.

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Parkdale third graders sing "12 Disaster Days of Christmas"

Welcome to your sing-able Christmas gift list. What follows is an emergency rendition of “12 Days of Christmas” – for outfitting your home or car in case of snow storm, earthquake, flood or other emergency. Read it as a simple list, or sing it to the tune of “12 Days” – you know, as in “ … and a partridge in a pear tree…” Not to make light of it, but the song is a familiar framework for a set of gift ideas that you could consider gathering together, even if the recipient already owns items such as a bunch of coats, tire chains and flashlights. Stores throughout the Gorge are stocked up on all these items. Buying all 12 days might be prohibitive, but here are three ideas for checking any of the dozen off your list (notations follow, 1-12.) The gift items needed to stay warm, dry and safe are also coded to suggest items in your abode (A) in your car (C) or both (B). 12 Gallons of Water (A) 11 Family meals (B) 10 Cans of propane (A) 9 Hygiene bags (B) 8 Packs of batteries (A) 7 Spare coats (B) 6 Bright red flares (C) 5 Cozy blankets (B) 4 Tire chains (C) 3 Flashlights (B) 2 cell phone chargers (B) 1 And a crush-proof first aid kit (B) Price ranges? Here’s a few quotes for days Three, Two, Four and Nine: n A family gift of flashlights (three will run $15-30, Hood River Supply, Tum-A-Lum) n Cell phone chargers (two will run $30-60) n Tire chains (basic set, $30, Les Schwab, returnable if unused for the winter) n Family meals ($100 or so should cover the basics for three or four reasonably well-fed days) n The home kit should be kept in a handy place near an exit, and remember that water needs to be replenished every few months. If you have a solid first aid kit already, switch out the gift idea with “and-a-sto-o-u-t- tub-for it-all …” Otherwise, it’s a case of assembling your home or car kits and making sure all members of the family know what the resources are and how to use them (ie flares and propane). Emergency situations are at worst life-threatening, at best deeply uncomfortable if you and your family are left without power for an extended period, or traveling and find yourself in a situation where you need to wait out a storm, lengthy traffic delay, or other crisis. Notes on the 12 gift ideas: 12 – Gallons of water: that’s one per person in a four-member family to last for three days, the recommended minimum to be prepared for utility outages. 11 – Easy-open packaged goods, energy bars, dried food and nuts are good things to include for nutrition. Think of what your family of four needs for three days to stay fortified and hydrated (see number 12). Can-opener also recommended 10 – If you have a propane camping stove, keep extra fuel handy. 9 – Hygiene bags: put packaged moistened towelettes, toilet paper, and plastic ties in large garbage bags (for personal sanitation) Resource list courtesy of Hood River County Emergency Management, Barbara Ayers, manager/ 541-386-1213. The county also reminds residents to Get a Kit, Make A Plan to connect your family if separated, and Stay Informed. See www.co.hood-river.or.us to opt-in for citizen alerts. Enlarge



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