Oregon Geology - Tsumamis - Lincoln City
Posted by: Groundspeak Premium Member silverquill
N 44° 58.072 W 124° 01.059
10T E 419748 N 4979884
This marker at the D River Beach Wayside in Lincoln City gives the geological history of the Oregon coast which has produced tsumamis in the past and will likely do so in the future.
Waymark Code: WMCX06
Location: Oregon, United States
Date Posted: 10/21/2011
Published By:Groundspeak Premium Member Volcanoguy
Views: 13

Lincoln City, Oregon

The D River Beach Wayside is a day use State Park recreation area on the south bank of the D River in Lincoln City. This sign is at the beach edge.

This area of the coast is very flat with numerous streams and rivers, including the D River here which is the outlet of the large Devil's Lake a scant 120 feet from the high tide mark, making this area very prone to serious damage from a tsunmai. The entire area of Lincoln City is barely 20 feet above sea level. In fact, a tsunami in 1700 did cause extensive damage as documented in a marker for The Great Tsunami of 1700, just three miles south of this location.

The main text of the marker:

Devastating waves called "tsumamis" can strike Oregon's coast at any time. These giant waves are caused
by great undersea earthquakes. Such earthquakes can occur along the Cascadia Subduction Zone, one of
the largest active faults in North America. This fault zone lies 32 to 70 miles offshore and roughly parallels
the coast.

Tsunamis are dangerous and destructive. They have struck the Oregon coast repeatedly and will again in
the future. Tsunamis can follow within minutes of an earthquake. They move rapidly but quickly run out
of water as they sweep inland and uphill. Flooding can occur several miles inland along rivers and
streams. Remember, most tsunamis are not solitary giant waves, instead, many large waves may strike the
shore over the course of several hours.

A cross section diagram carries this description:

The Juan de Fuca Plate is moving away from the Juan de Fuca Ridge and is being forced
under the overriding North American Plate. This geologic process is called subduction.

A coastal map from British Columbia to northern California showing the plates and fault zones carries this description:

The earth's surface consists of a series of "plates." These plates are constantly shifting and sliding over, under, or past each other. When a sudden movement occurs between two plates, we experience and earthquake.

A section giving the procedure to follow in case of a tsunami reads:


* Protect yourself during the earth-
quake. After the earthquake,
immediately go inland and uphill.

* Do not return to the beach after the
first tsunami wave -- more may arrive
for several hours>

* Wait for official notice from
authorities that the danger has
passed before returning to the beach.

For additional information, contact your local
emergency planning office or the Oregon
Department of Geology and Mineral Industries.

The sign bears the logos of the Oregon Travel Information Council, Oregon State Parks, and Sea Reach Ltd.

Historic Topic: Geological

Group Responsible for placement: State of Oregon

Marker Type: City

Region: Coast

County: Lincoln

Web link to additional information: [Web Link]

State of Oregon Historical Marker "Beaver Board": Not listed

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Recent Visits/Logs:
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dkestrel visited Oregon Geology - Tsumamis  - Lincoln City 12/30/2013 dkestrel visited it
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