Overnight Tsunami Watch…And Wait

— by Dave Halloran, County Dept. of Emergency Management —

If you are like me, you woke up in the early morning hours today to a phone call, text or other notification of a potential tsunami stemming from the 7.9 magnitude earthquake last night in the Gulf of Alaska. A flurry of activity followed with phone calls between DEM Director Brendan Cowan and myself, the Sheriff’s Office 911 dispatch center and the State Emergency Management Alert Center. Then came updating local first responders, Facebook and Twitter with any new updates to the situation.

We’ve been advised previously that an earthquake in the Gulf of Alaska would not cause a tsunami threatening our island community, but wanted to be sure this was the case. The Tsunami “Watch” notification estimated it would be over four hours before any possible impact to the islands. During this time we reviewed the information released by the U.S.Tsunami Warning Center (tsunami.gov). This information remained consistent with previous information given to us – that there would be little or no impact here. Indeed, there is little threat to the islands from a long distant source – but the primary threat is from a local earthquake that we would feel here. As the saying goes, “When the ground  shakes, go to high ground”. Knowing that feeling major shaking as our warning is important – we don’t need to rely on expensive and difficult to maintain sirens for a warning.

If reports from locales closer to the earthquake and from the Tsunami Warning Center indicated a tsunami threatening the islands had been generated we would take any or all of these actions:

1) Updates to the DEM  facebook and twitter pages.

2) Notify local emergency responders and government leaders.

3) Notify Islanders using our “Island Alerts” notification system to cell phones and broadcast radio/TV.

4) Potentially have First Responders drive notification routes broadcasting warnings using PA loudspeakers. If time and responder safety permit, make some door to door notifications.

Areas of most concern in the islands can be seen at this map https://sjcgis.org/tsunami-inundation/

Ultimately, the “Watch” was canceled after several hours. Fortunately, there have not been any reports of tsunami from any coastal area, and we have been provided with a great opportunity to give this information as a preparedness reminder.

You can learn more about tsunamis and the San Juan islands on the DEM website here www.sanjuandem.net/tsunami . This page highlights the primary tsunami threat which is from a Cascadia Subduction Zone earthquake. Please follow the DEM  facebook and twitter pages, and sign up for Island Alerts (sanjuandem.net/alerts). We use these tools to send emergency information to the public.

Finally, if you have any questions about the tsunami watch, or any other preparedness question, please write dem@sanjuandem.net, or give a call to 360-370-0587.

Now, get ready for the next windstorm…thanks!