Jackson County, Oregon, USA

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May 30, 2023
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Tsunamis? In Jackson County?

tsunamiAlthough Jackson County is not at direct risk from a tsunami, there are still a few important facts that our residents should know.

Although there are many miles of roadway and a mountain range that separate us from our coastal neighbors, many of us visit the coast regularly.

According to the National Oceanic and Atmospheric Administration (NOAA) A tsunami is a series of waves with a long wavelength and period (time between crests) generated by a large, impulsive displacement of sea water. Time between crests of the wave can vary from a few minutes to over an hour, but generally are in the range of 15 to 30 minutes. Tsunamis are often incorrectly called tidal waves; they have no relation to the daily ocean tides.

There are two different types of tsunamis:

A distant tsunami is one produced by an earthquake far away, on the other side of the Pacific Ocean. It will likely take 4 or more hours for the waves to reach the Oregon coast. A distant tsunami will produce smaller and less powerful waves, but it can still cause damage. The National Tsunami Warning Center issues distant tsunami alerts for Oregon.

A local tsunami is one caused by an earthquake off the coast of Oregon along the Cascadia Subduction Zone – a 600-mile long fault zone that sits off the Pacific Northwest coastline. Following strong ground shaking from the earthquake, the waves from a local tsunami will reach the cost in 15-20 minutes.
Signs that a tsunami may be imminent include:

* Hard ground shaking for 20+ seconds near the coast.
* A sudden sea level withdrawal.
* Tsunamis may be accompanied by loud, booming noises.

Many of Oregon’s coastal communities have siren warning systems that will activate if a Tsunami has been forecasted.

When you visit the coast, pay attention to the blue Tsunami Evacuation Route signs. Local businesses, including hotels/motels and restaurants, should have information about Tsunami evacuation.

TsunamiEvac-NW is a free app for Android and iOS that allows users quick access to Tsunami evacuation route maps.

Visit the National Tsunami Warning Center website for additional information.

Another important fact is that our neighbors in Coos and Curry Counties get most of their local news from television stations located in Medford. For this reason, you may be sitting in your living room in Jackson County when you see a Tsunami alert scroll along the bottom of the screen.  Is someone playing a dirty trick? Is there a wall of water tall enough to crest the coastal range headed your way? The answer to both questions is a resounding NO! However, it’s likely that the only way for a television viewer on in Coos or Curry County to get the alert is if our local stations broadcast it.

When the National Weather Service sends a Tsunami alert, it is sent to weather radios, television and radio stations in Coos and Curry Counties, but in order to reach most television viewers, it must also be sent to the stations where their local news originates – stations such as KDRV, KOBI and KTVL. These stations have special equipment that is programmed to “listen” for alerts issued to other counties (such as Coos, Curry and Josephine) that receive their television broadcasts from Medford.