Tsunamis and detecting

[Billinoregon]

Friends, I am not trying to be morbid or uncaring here, but I am curious what effect a tsunami has on beach strata. I am wondering if there is any anecdotal evidence regarding conditions after the Indian Ocean tsunami in 2004 and the tsunami in Japan in 2011, and what challenges or opportunities they eventually presented to detectorists. I ask because I live in a state -- Oregon -- whose entire coastline up to as much as 100 feet above sea level is at grave and imminent risk from a Cascadia subduction zone earthquake and tsunami. I realize that it might be months or years before infrastructure could be restored to even allow access to the coastal zone in the worst-case scenario, so this is mostly a hypothetical exercise.

 

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[bigfoot1]

I would surmise it would be like swinging your coil at a local landfill.

 

[pepperj]

It'd be something like this, a detector would not much good.

 

[stefen]

As you may be aware, as an example, the tsunami that destroyed Crescent City CA that borders on the California / Oregon border changed the beach structures.

In addition to modifying the sand banks accumulated in the Pacific Ocean, miles offshore.

Today many of the river outlets from south of Eureka to mid-Oregon coast are blocked by excessive sand buildup, and hence is directly destroying the Salmon migrations of the fry and return of the adult Salmon.

May of the fish are dying in shallow puddles, even going blind.

The future fish spawn runs are directly impacted.

In addition, the warmer waters of El Nino are driving octopus northward into this same region.

Natures balance is effected by changes along the north coast.

The currents from Japan has been depositing a multitude of junk along the beaches by Crescent City and southern Oregon.

A floating concrete dock and boats of all sorts are among the many finds.

As to recreational MD'ing, that's the least of anybody's worries.

 

[Tom_in_CA]

If your question is about beach erosion, I don't think they will do much good. Because the wave(s) produced by those, are singular "whams". Ie.: one giant wave, or whatever. Contrast to the type that erode the beaches and bring out the md'rs, is the consistent ones that hit cumulatively all day long, or for several days. A single wave doesn't do it. It needs to be the back-to-back action of entire tide cyles.

And also: A lot of it is hype anyhow. That one you allude to in 2011, brought out a bunch of lookie lous, and did some damage at a few yacht harbors (d/t sailboats and such raised up in their slips). But really was much-ado-about nothing, in-so-far as the open facing beaches went.

 

[Billinoregon]

Tom, you are probably correct. In many tsunami scenarios, the water recedes well below normal beach heights, followed by the big wave gathering everything in its path as it rushes inland, sometimes for several minutes as we saw in Japan in 2011. Then all that water volume recedes, leaving a vast debris field. While it would certainly pull some beach sands offshore with the receding action it would be nothing like the effect of tidal series and powerful swells sets.

Stefen, are you in Humboldt or Del Norte County?
Arcata High School class of '71 ...

 

[stefen]

Humboldt

 

[Oregon Viking]

If your question is about beach erosion, I don't think they will do much good. Because the wave(s) produced by those, are singular "whams". Ie.: one giant wave, or whatever. Contrast to the type that erode the beaches and bring out the md'rs, is the consistent ones that hit cumulatively all day long, or for several days. A single wave doesn't do it. It needs to be the back-to-back action of entire tide cyles.

And also: A lot of it is hype anyhow. That one you allude to in 2011, brought out a bunch of lookie lous, and did some damage at a few yacht harbors (d/t sailboats and such raised up in their slips). But really was much-ado-about nothing, in-so-far as the open facing beaches went.

10 million dollars in damage to our port. Oregon Coast tsunami: Brookings, Crescent City, Depoe Bay report serious damage (photos, video) | OregonLive.com

I did not see any beach erosion/damage. Of course the big one's coming...the experts claim.

 

[Tom_in_CA]

10 million dollars in damage to our port.....

Yes sure. Wasn't saying they don't do damage that cost $$. So too did Twin Lakes beach in the Santa Cruz CA suffer dollar damage to their boat slips. But was just saying it's not the beach erosion for our purposes of md'ing. A singular couple of waves, versus those of normal storms/swells, that hit continuously during an entire high tide over the full day.

And yes: keep an eye on this winter's supposedly big el nino. Maybe it'll produce the stormy seas that will eroded some of our beaches for good md'ing purposes like previous el nino's have done.