Posted on 06/14/2005 12:38:57 PM PDT by Strategerist
If a giant magnitude 9 earthquake strikes someday along the coast of the Pacific Northwest, or if, against all odds, an errant asteroid plunges into the ocean many miles off California, a monstrous tsunami could drown low- lying lands all up and down the continent's western edge -- and now a UC Santa Cruz scientist has calculated the sweep of such an event.....
...To model the event's effects, Ward assumes that in a huge quake on the Cascadia subduction zone, the two crustal plates would abruptly slip apart vertically by at least 50 feet in three successive blocks from south to north, generating a 9.2 magnitude quake. Aside from enormous quake damage on land for hundreds of miles, Ward estimates the resulting tsunami would pile a wave more than 20 feet high crashing onto the Oregon-Washington coast, inundating Seattle and the entire Puget Sound region as well as Portland and the mouth of the Columbia River.
(Excerpt) Read more at sfgate.com ...
Evidence for possible precursor events of megathrust earthquakes on the west coast of North America
Andrea D. Hawkes, Centre for Environmental and Marine Geology, Dalhousie University, Halifax, Nova Scotia B3H3J5, Canada, et al. Pages 996–1008.
Keywords: precursor, megathrust earthquake, foraminifera, thecamoebian, marsh/forest transition.
For many civic planners, the time frame of 300–500 years as a periodicity for the return time of megathrust earthquakes on the west coast of North America is too long to plan by. However, in this paper, we report a possible precursor mechanism that appears to have a 3–10 year time frame that provides 3–10 years' warning time, which is a realistic time frame for civic planners. The precursor was detected using changes in microfossil assemblages (protozoans that leave a fossil record--in this case, foraminifera and thecamoebians) in cores from Alaska and Oregon. The assemblages change in response to small elevational deviations a few years before mega-thrust earthquakes that occurred in coastal forests and salt marshes along the west coast of North America. This technique provides a reliable and economical tool that could save thousands of lives and millions of dollars of property damage in large cities like Vancouver, British Columbia; Portland, Oregon; or Seattle, Washington.
Tsunami history of an Oregon coastal lake reveals a 4600 yr record of great earthquakes on the Cascadia subduction zone
Harvey M. Kelsey, Department of Geology, Humboldt State University, Arcata, California 95521, USA, et al. Pages 1009–1032.
Keywords: tsunami, Cascadia subduction zone, paleoseismology, plate boundaries, subduction zone.
Earthquakes on the Cascadia subduction zone, which is the offshore fault that runs from northern California to southern Canada, generate destructive tsunamis. When these tsunamis spill over into low-lying coastal lakes, they can leave a record of their disturbance as layers of imported beach sand and wood debris preserved in the lake mud. Using this technique, four paleoseismologists (Harvey Kelsey, Humboldt State University; Alan Nelson, U.S. Geological Survey; Eileen Hemphill-Haley, Humboldt State University and Rob Witter, William Lettis and Associates) have discovered a 4,600-year record of tsunamis that have invaded the southern Oregon coast. During this time, fourteen tsunamis have entered Bradley Lake, an 18–20-foot-high lake dammed behind coastal sand dunes. Each tsunami carries beach sand and marine organisms into the lake. Detailed study of these sand layers in the lake shows that the tsunamis consisted of multiple waves that overtopped the sand dunes. Based on the height of the sand dune dam, the paleoseismologists estimate that the tsunamis were at least 18 to 20 feet high, with the larger tsunamis much higher than this minimum height. Time intervals between tsunamis have been as long as about 1,200 years and as short as a few decades. The tsunamis (and hence accompanying earthquakes) appear to come in clusters; for instance, between ca. 850 BC and 250 AD, there were no tsunamis, yet from AD 250 to AD 950, there were at least four. The most recent tsunami was 300 years ago and was preceded by a 700–800 year time gap with no tsunamis. The tsunami of 300-years-ago, which other geologists have determined was caused by a subduction zone earthquake that broke the seafloor between northern California and southern British Columbia, may be the start of a new cluster of closely spaced-in-time subduction zone earthquakes and tsunamis. Although the tsunamis are documented at this one site, it is likely that each tsunami affected a much larger coastal area, encompassing all or most of the northern California to southern Canada coastline. Also, Cascadia tsunamis can travel across the Pacific Ocean and lead to hazards at other Pacific coast localities.
So the wave would take out San Franfreako, Santa Cruz, and LA ... so where's the problem ????
Would each victim get millions of dollars of taxpayer money or would they be relying on insurance that they should have bought...?
ping
The problem is the wave wouldn't be large enough to take out Redmond.
If the US accidentally attacked itself with our entire nuclear arsenal, many people would die.
If ...
I'd love to see a map showing how far inland the water would go. I'm about 4 miles inland and might have to get ready to own ocean front property. :o)
The problem is that it would take out San Diego too...and since I live there, I would consider that to be a tad problematic
Cool. My office will be lakefront.
One thing the article wasn't clear on was exactly how well the wave propagates into Puget Sound.
At least one good thing about the Indian Ocean Tsunami is that people finally understand what one actually is; previously there had been very little footage of one, besides some grainy black-and-white from Hilo Hawaii in the 1940s, and a bit from Japan more recently; documentaries and movies kept showing curling surfer waves from Hawaii and whatnot, and didn't convey it's basically a flood not a single curling wave. So I think people understand that even a 10 foot tsunami is disastrous.
Congress needs to pass a law prohibiting this from happening.
Congress needs to pass a law prohibiting this from happening.
WE'RE DOOOOOOOMED!!!!!!!!!!!!!!!!!!!!!
Homeless, women and children effected most !
I think that someone could make a layered map of how far inland a wave of x feet would go and draw a line, then an xx feet wave line, etc. The different geographical differences would need to be taken into consideration.
Why bother, the 9th Circuit would overturn it because it would restrict water molecules from freedom of association with dry land. Then again, if there are some spotted owls, children, rainforests and/or minorities in the path... what to do, what to do.
Mexico would send some people.
If I bought lottery tickets...I could win.
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