North Idaho celebrates Earth Day with earthquakes

April 27, 2015

April 24, 2015 To the Editor: At approximately 7:32 p.m. Thursday, April 23, 2015, I was sitting on my couch watching television when I noticed my four dachshunds awaken beside me and appeared to be startled. Just as they started to bark, I heard a rising amplitude grinding, dragging sound followed by a high-frequency vibration within my house. I could hear dishware rattling within my cabinets, and pictures were rattling on the walls. This lasted for about eight seconds. Having experienced several earthquakes before ranging from 2 to 7 on the Richter scale, I knew immediately what was happening. I called a few of my neighbors; some felt it, some did not. The U.S. Geological Survey reported this quake at magnitude 4.1 at a depth of just over 3 miles with the epicenter located approximately 15 miles southeast of Sandpoint at a location under Lake Pend O'Reille near Farragut State Park/Bottle Bay. As far as earthquakes go, this is rather shallow and resulted in the very noticeable seismic activity given the magnitude. At approximately 10:45 p.m., a second earthquake hit. This temblor arrived with a very different low-frequency rumbling, roaring sound followed by upward, downward, and sideways motions within my house. This shaking motion lasted a bit longer than the first one and seemed significantly stronger. I noticed my walls appearing to sway. My dogs were acting gun shy at this point. The U.S.G.S. reported this quake at a magnitude of 4.2, and the epicenter was further north this time, but still underneath Lake Pend O'Reille at a location between Hope and the Forrest Bird Aviation Museum. This quake was more widely-felt than the first one by residents here in Bonners Ferry/Boundary County. I gave a telephone interview during KHQ-TV's (NBC;Spokane, Washington) 11:00 p.m. news live broadcast, giving my account of last evening's experience. Shortly thereafter, I retired for the night. At approximately 1:28 a.m., I was awakened by a third temblor which the U.S.G.S. reported at a magnitude of 3.3 with the epicenter near the same location as the second one. I probably would have slept through this one had I not been hypervigilant from the first two. Yesterday, a 2.8 magnitude earthquake was reported as well in Council, Idaho, located north of Boise. This morning at 6:56 a.m., a magnitude 6.2 earthquake was reported at the southern tip of Queen Charlotte Island located off of the west coast of British Columbia. This "swarm" of seismic events appears related to the subduction of the Pacific plate underneath the North American plate. This activity results in an upward thrust of the North American plate. Some seismologists have predicted a massive 8.0 or greater magnitude earthquake to occur along the Cascade fault region within the next 30 years. Seismic and/or volcanic activity are the way nature relieves the stresses built up by movement of tectonic plates. Recently, Kalispell, Montana experienced a minor earthquake and there have been several accounts given about the potential of the supervolcano that rests beneath Yellowstone National Park. I do not think there is cause for alarm at this time, but we might be in for an interesting period. Gerald Higgs