The earthquake is coming. Experts just don’t know when it will hit. They know it’s happened before. In fact, magnitude 9 Cascadia earthquakes occur here from intervals as short as 300 years and as long as 800 years. The last “megathrust” Cascadia earthquake occurred in 1700. Recent studies by Oregon State University geologists say there is a 10 percent chance that one could happen in the next 50 years.

If that prediction makes you want to run for the mainland, stay in your chair because Tim Walsh, chief hazard geologist of the Washington Department of Natural Resources, has good news.

“Most people will survive the earthquake by doing the right thing,” Walsh said. “Surviving is possible. Absolutely.”

On Sunday, April 7, 2 p.m at Orcas Center, Walsh will explain just what a “megathrust” Cascadia earthquake is in his lecture “The Next Big One: Earthquake and Tsunami Risks in the San Juan Islands.” There will be a Q&A session and a reception. The talk is part of the Crossroads Lecture Series, which brings a variety of speakers to Orcas Island to share their expertise on timely and important issues.

Walsh will discuss the risks and potential impacts of such a major earthquake, the resulting tsunami, and how it will affect islanders. The 45-minute lecture will also cover how residents will survive this disaster. Walsh estimates that islanders will have an hour and a half to get out of harm’s way, which essentially means getting to higher ground.

“People should not afraid, but should be aware of all of those kinds of things that go wrong and put them in perspective,” Walsh said. “A Cascadia subduction zone earthquake is a rare event, but it’s best to know what to, not dwell on the event.”

Walsh earned bachelors and masters degrees in geology from UCLA, and has been practicing geology in Washington for more than 32 years and has taught at South Puget Sound Community College for nearly 30 years. Walsh has performed geologic mapping in many parts of the state – as well as tsunami hazard mapping, active fault characterization, and landslide and abandoned coal-mine hazard assessments. This is his third lecture in the islands and he recalls most islander being receptive to his warnings.

“Are we ready for the next big one?” Walsh said. “To paraphrase George Bernard Shaw, we learn from experience that we don’t learn from experience.”

Tickets are $10 at Darvill’s Bookstore,  at www.orcascrossroads.org or at the door. Some complimentary tickets are available in advance at the Senior Center.