Tsunami

Tsunamis are a series of waves that are generated when large earthquakes cause the sea ﬂoor to displace the water column above. These dangerous waves can be caused by coastal or submarine landslides or volcanoes, but they are most commonly caused by large earthquakes under the ocean, such as one from the Cascadia Subduction Zone. The Paciﬁc Coast is at risk both from a local tsunami, arriving within minutes of an earthquake, and distant tsunamis, taking several hours to reach the shore.

Since 1854, 21 tsunamis have impacted the Oregon Coast. The last two damaging tsunamis were in 1964 as a result of the Great Alaskan Earthquake, and in 2011 as a result of the Great Tohoku Japan Earthquake that caused severe damage and contributed to the deaths of four people on the Oregon Coast.

OEM has published a downloadable Tsunami Evacuation Drill Guidebook to help communities plan and recover from a tsunami.

For information about tsunami evacuation drills or the Geological Hazards Program at OEM, contact:

Althea Rizzo, Geological Hazards Program Coordinator

503-378-3936

althea.rizzo@oem.oregon.gov

What To Do: If you are near the coast and feel a large earthquake, see a sudden rise or draining of ocean waters, or hear a loud roar from the ocean, a tsunami may follow. During an earthquake, Drop, Cover, and Hold On until the shaking stops. Walk inland and up to high ground and stay there. Do not wait for an official warning. A tsunami could come ashore in a few minutes.

Tsunami Alerts: Tsunami messages are issued by Tsunami Warning Centers following a possible tsunami-generating

event. Tsunami messages may be updated or canceled as information becomes available. There may not be enough time for an official warning, so it is important to recognize the natural warning signs described in the "What To Do" section above. Visit the National Weather Service (NOAA) website to learn more about the four types of tsunami alerts (Warning, Advisory, Watch, Information Statement).