How Many Earthquakes in the Pacific Northwest

Aug 12, 2021

Today we will share information on earthquake activity that has occurred in the Pacific Northwest Seismic Network’s region over a recent two-week period. You can access this information from the comfort of your computer at www.pnsn.org. Before we get to deep into this discussion, I should note that I have been monitoring the pnsn.org site since 2005 when I was with the Red Cross. In some cases, I would reference this site daily to incorporate the findings into earthquake preparedness presentations. So, I would ponder that I have referenced this stie map somewhere between 7 and 10,000 times over the past 16 years. I will also share, that it was extremely interesting to watch the map over time. Looking at the map as often as I did, I would see weeks with very little activity and some weeks with significant activity, in my opinion. I seem to remember 25 events was the lowest recorded seismic activity that I ever witnessed and upwards of over 200 in a different two-weeks monitoring time. There really was not a clear trend that I could see. Nor was there any way for me to predict what the map would reveal from week to week. I was unable to glean any assemblance of frequency, location, magnitude, depth, or any other recorded measure on the map. Other than to say that every time I pulled up the seismic map there was one consistency…….There was always seismic activity. Some weeks would be on the lower end in the region and other times it would be a bit higher. Regardless of the week, there was always activity. As I pulled up the map on the 5th of August 2021, for this video, it revealed that there were 198 earthquakes that had occurred over the two weeks prior and that they ranged up to a 4.2 Magnitude, however the 4.2 M occurred outside of the network. You can see the largest block off the coast of Oregon that correlates to the 4.2 Magnitude event. The rest of the seismic activity registered less than 4.2 Magnitude, which is actually interesting, because anything less than a 4.0 Magnitude will likely go unnoticed by the common person. In most cases, it is at about the 4.0 Magnitude rating that some seismically sensitive people will feel the shaking. The majority of folks will feel the earthquake at a higher magnitude. As the magnitude climbs and more people feel it, the likelihood of potential damage to the areas in and around the epicenter of the event increase exponentially with the increase in Magnitude. I share this with you, so that you can see the value in preparing today. Remember, that each of those dots on the map represent a seismic event and if you hadn’t already noticed, please take a look at where most of the activity is occurring. As you look, please envision our transportation system and any key traffic routes, as upon looking deeper you should recognize that most of that activity runs along the I-5 corridor. This I can share, is the one clear common thread from week to week upon looking at this map over the years. The most seismic activity seems to be running parallel to where most people live in the State of Washington and Oregon. Folks let’s not wait for the next one. Get prepared soon, if not today! Do it on your own by continuing to follow our weekly tips or join us in September and download our Home Preparedness series, so that you and your loved ones can quickly respond and recover from the next large scale seismic event.