Documentary on how ill-prepared Oregon is for the Cascadia Subduction Zone earthquake. (Portland: how much, hotel)

[PNW-type-gal]

Originally Posted by Cloudy Dayz

LOL, I was in California during Y2K and nobody even cared. Of course now the apartment complex I live in has 'What To Do In The Event of an Earthquake' posters all over the place. I never saw anything like that in California, and there are earthquakes in California all the time. Here they happen once every 300 years, supposedly.

The Cascade Mountains, from British Columbia into California, are made up of several volcanoes, many of them considered active and there are small earthquakes associated with them every day (as well as large and small eruptions). There are also many faults, mostly on a NW trending line, that can generate up to about an 8.0 or thereabouts, depending on the location and type of fault. There were two bigger earthquakes in Oregon in the 1990s, the Scotts Mills Earthquake and the Klamath Falls Earthquake.

https://en.wikipedia.org/wiki/1993_K...ls_earthquakes
https://en.wikipedia.org/wiki/1993_S...lls_earthquake

The Cascadia Subduction Zone events are caused by an entirely different mechanism, which is why they are capable of much higher magnitudes and along a much great area. Unlike a fault-based earthquake, which generally has a single, pin-pointed epicenter, the break along the tectonic plates can happen over a large area. So, unlike California, where if you weren't within 15-20 miles of Northridge the impact was minimal, damage can happen over a much bigger area.

[Larry Caldwell]

Originally Posted by texasdiver

That said, there are plenty of easy things to do to prepare. I keep a couple extra propane cylinders around so I could could for 6 weeks on my BBQ grill if power and gas are out. I have a backpacking water filter so I can pull water out of the stream behind the house if necessary. I have at least a month's worth of staples and canned goods in the house. Not so much for prepping but just because I buy in bulk. And I have a ton of camping and backpacking equipment available if the house is uninhabitable. When we lived in Texas, everyone bought emergency backup generators for hurricane preparedness but I don't really see the point of that up here as we don't get the swelteringly hot summer weather and one can get by fairly easily without electricity for a reasonable period of time. We are mostly vegetarian so I don't have a big freezer full of meat anymore that can go bad.

That is more a lifestyle than prepping for most people. Of course you keep propane on hand. You might run out during a cookout and ruin the steaks.

The primary things you need to provide during an emergency are warmth, water, and food. A tent and some long johns will take care of warmth. A water filter will take care of the water, in most areas. You can do without food for a couple weeks, or keep some canned goods and dry staples around.

The really critical thing is water. You can go hungry for a long time, but three days without water and you die. My friends in the Bay Area stock 250 gallons of drinking water in their basement in plastic carboys. Every year they dump them and refill them from the tap. They estimate that will last them twice as long as they were without water after the Loma Prieta quake in 1989.

[pnwguy2]

This is a pet-topic for me. I lived in Eugene, and for a time out in Newport. I have also studied this issue.

My conclusions are this area would be in severe trouble in a major subduction quake. More than Washington, or even Northern California, due to the close population in Oregon to the coast.

As for timing, I think the OP has it about right. The last severe subduction quake occurred in 1700. This has been proven. The best scientific evidence is this will repeat within 300-500 years. So, as I have posted before, that means we are in the "window".

Today, we see signs of "entering" or "leaving" tsunami warning areas. I think that is a good start, but I don't know how the public would deal with a warning in the short period of time (usually less than 25 minutes), with the highway infrastructure currently in place...mostly a two-lane highway.

There is no question that Oregon has the most populated coast in the Northern US coastal region, from Northern California to Western Washington. This is eye-opening for sure.

I'm not sure what else can be done. Many insist on living in this danger zone. I would hope most have a get-away plan in such an emergency, but not certain most do.

[Larry Caldwell]

There's no doubt the coast would be hit hard, particularly during tourist season when tourists far outnumber the locals and all the summer homes are full. Some areas are safe enough from a tsunami, and will be fine as long as they stay on the hillside. Astoria would be fine, Warrenton would be near 100% fatalities. Anything 100 yards up hill in Yachats would be fine. The entire dunes at Florence would be under water, 10 miles from the beach.

The coast also is much closer to the fault. The quake will be 4x as violent there than it will be inland. The North American Plate is a big spring and it's wound pretty tight. People expecting to escape by car may find it has been tossed off the road.

[Terryj]

The problem with subduction zone earthquakes is the length of time they last, most faults that have lateral shifts only last for a few seconds, but subduction quakes can last for a few minutes and the shaking will be violent. On the Oregon coast the damage will be catastrophic, the only bridge I can for see surviving might be the Alsea Bay Bridge at Walport, most of the bridges on 101 I don't think would survive a 9.0 earthquake,this would leave most of the towns along 101 cutoff from any relief. The bridges that the earthquake didn't take out the tsunami most likely would, especially the low laying ones like the ones at Gold Beach, Winchuck River Bridge, Ten Mile Creek Bridge just to name a few there are probably a dozen more. A lot of the roads inland will most likely be blocked by landslides, the only way to bring relief in those towns would be by air and boat if the harbors allow. People along the coast really need to be prepared to go a long while without any support.

[pnwguy2]

As I posted earlier, the one area that I really feel is at most risk is the Oregon Coast. I lived there for a brief period in the early 2000's, but had not considered the threats at that point. Today, I would never live there, but that is just me. Yes, it is a beautiful area, perhaps the best scenery on the Pacific on the West Coast of the US, excluding Alaska. I simply would not want to be there when this quake occurs...who would? That said, it could happen this week or 100 years from now. There is no way to predict the timing, but we do have enough information that it will be coming eventually.

[Terryj]

I lived on the Oregon Coast for a few years, I agree, the Oregon Coast is a beautiful area. I now live in Medford, frankly, I don't how this town would fair having a 9.0 quake 170 miles away, I can guess that the damage would be significant.

[PNW-type-gal]

Originally Posted by Terryj

I lived on the Oregon Coast for a few years, I agree, the Oregon Coast is a beautiful area. I now live in Medford, frankly, I don't how this town would fair having a 9.0 quake 170 miles away, I can guess that the damage would be significant.

I've been to a couple of the emergency preparedness meetings and I think that the city and SOME of the county has a clue about what the major problems are likely to be.

The Viaduct, for instance, is likely to fall, which will require routing I5 traffic through the city, likely on Hwy 99 (assuming, of course, that I5 through the Siskiyous stays intact). Otherwise the plan is to route north/south traffic through Hwy 97 (coming through the Cascades at Hwy 58 and at Weed on I5).

The problem with that is that 97, where it passes right by Upper Klamath Lake, runs right along a fault and the hillsides there dip right toward the lake, so a big long shake has the potential to slide those hills right in to the lake. he detours to the west and east of that add a lot of miles on the trip. When I lived near Crater Lake, Hwy 97 by the lake would be shut down due to a nasty head-on collision once or twice a year and there wasn't much of an alternate.

Beyond transportation issues, they do have some plans for the water system, electrical grid, sewer systems. It isn't as comprehensive as one could wish, but at least they've started looking at it. There are a lot of facades in Jacksonville, downtowns of Medford, Ashland, Central Point that will be pretty iffy as well, but that isn't the long-term issue that emergency services, food, water, heat, lights, sewer is.

[WestGuest]

Are there maps for each county with afflicted areas? Is the east side of Coos Bay at risk?

[Larry Caldwell]

Anything east of the Cascades is unlikely to be hit very hard. That's a long way from the fault line.