Earthquakes and Tsunamis on the Oregon Coast

1. Earthquakes and Tsunamis on the Oregon Coast Patrick Corcoran, Hazards Outreach Specialist, Sea Grant Extension, OSU Seaside, OR Japan 2011

2. The Bottom Line Giant Earthquakes Happen Here! They Occur Regularly in Geologic Time Our Last one Was in 1700 (313 years ago) Given 10k year Averages, We’re About Due EXPECT IT!

3. Seriously, this is the shift that matters… EXPECT IT! It will change the way you live

4. The 3 Things You Need to Know • Big earthquakes make big tsunamis. Know the difference between Local and Distant events. • If you feel the earth quake, Get to high ground fast (15-30 min). Locate now the Danger Zones and Safe Zones where you live, work, and play. • Instruct Loved Ones to get to high ground, stay there overnight, and find each other at a shelter. ID non-local contact person to call. Source: Patrick Corcoran, Sea Grant Extension, Oregon State University

5. 2 Scenarios Exercise Distant Event: What did you do on 3.11? What would you do differently? LOCAL EVENT! Ranging from an M8 quake at either end of fault, with moderate shaking locally, limited, localized tsunami damage. To a Full Rip 9 M9 quake underfoot. Major destruction, liquifaction, subsidence, landslides, large tsunamis and inundation.

6. 3 Types of PNW Earthquakes • Crustal: near the surface of a plate • Interplate: between two plates adjacent plates • Subduction: overlapping plates, mega thrust

7. 3 Types of PNW Tsunamis GOOD: Distant events from anywhere outside the region (AK, JP, CH, etc.) BAD: Partial CSZ rupture (So. or N.) damage will be worse near epicenter and less so farther away UGLY: Full CSZ. Widespread regional disaster. Major quake, major tsunamis

8. 10,000 year average* recurrence: The entire length erupts M9 every 500 years The southern portion erupts M8 every 250 years The last event was event was 313 years ago…

9. 19 M9‘s in past 10,000 years !

10. What is known The PNW, at 313 years into the cycle of recurrence, is far enough into it that a prudent society would be better prepared (75% have happened by now)

11. Astoria Young’s Bay Evidence of the last four Cascadia events, estimated top to bottom as AD: 1700 1400 900 400

12. If you FEEL a large earthquake: immediately duck down, cover your head from falling debris, and hold on until the shaking stops. Stay put unless your building is damaged and dangerous, then moved to open ground. Avoid power lines, gas leaks, and fires. Administer first aid and help others find shelter. Execute your family plan. (What did you say you were going to do? Do you have the discipline to do it?) Expect aftershocks and related trauma and damage. Local Earthquake

13. M 9.0 Earthquake and Landslides… Source: Oregon Dept Geology and Mineral Industries

14. Amplification of Soil and Fill Source: Oregon Dept of Geology and Mineral Industries

15. Big Earthquakes Cause Big Tsunamis!

16. A large earthquake IS your warning that tsunamis are on their way in 15 – 30 minutes!!

17. Local Tsunamis • The areas vulnerable to surge and flooding by tsunamis include all beaches, shorelines, coastal waterways, and wetlands. Much development exists in these areas. • Locate where you live, work, and play on these maps and “know where to go” to avoid tsunamis when the next Big One occurs. There will be no warning, you will have 15 – 30 minutes to get to high ground. Period. • Maps portray the WORST case scenario for a LOCAL event. (Distant events create smaller tsunamis) Get maps at city halls, fire stations, etc. Source: Patrick Corcoran, Sea Grant Extension, Oregon State University

18. New Maps ! Evacuation Brochures: Worst case local worst case distant* Tsunami inundation maps (TIM): Show range of the inundations of the past 19 events. More nuanced. For planning purposes

20. 19 M9‘s in past 10,000 years !

21. How Do I Reconnect With Family? DISTANT No problem. Phones, roads and infrastructure may be busy, but intact. Drive home or stay overnight with “friends in high places.” • LOCAL Big problem. Instruct loved ones to get to high ground, stay there overnight, and find each other later at a shelter.ID a non-local contact person for everyone to call. Do not rush to meet at a designated place as that will likely require family to re-enter danger zones. • Power and all phones will be out. Roads and bridges will be destroyed. You will likely not be in communication for a while. Insist that everyone knows what to do to be safe wherever they are. Don’t re-enter inundation zones for 12 hours. Talk through these scenarios. Source: Patrick Corcoran, Sea Grant Extension, Oregon State University

22. Families and Loved Ones Do your loved ones understand this infrequent but real hazard? Do they Expect it? Will they take distant events in stride; but when the earth quakes move to high ground, stay there overnight, and find you the next day? Are you sure?

23. Neighbors and the Hood • Earthquakes: Structural design, egress out, etc. • Tsunamis: Location, and connectivity after • Training for residents, businesses

24. Map Your Neighborhood! • Connected communities are more resilient • We have lots of resources! Everyone has a contribution. • Be prepared enough to help others!

25. Overwhelming Opportunities Political leadership and government support Businesses and Chambers of Commerce Schools, hospitals and public heath Public works, ODOT, planning departments Individuals, families, and neighborhoods, CERTS!!

26. We’re Culturally Unprepared Research has only in the past 25+ years revealed that Cascadia erupts in Great (M9) earthquakes and tsunamis. It’s understandable that we’re behind the curve. But, we must make up for lost time. We must prepare commensurate with the risk—which is great. In Japan 2011, 20k people tragically died. But over 200k were in the inundation zone at the time. So, 90% of Japanese successfully evacuated!