Big Northwest coastal quake likely but not soon
Earlier this month, articles appeared in numerous publications about a massive earthquake that will someday hit the Northwest coast.
Some scientists speculate this event will be so strong that it will destroy thousands of homes and other buildings and devastate the region’s power grids from British Columbia to Northern California. They also say that a megatsunami would be generated within 15 minutes of the earthquake that would “create a 700-mile-long liquid wall.” Death tolls would be in the thousands or even the tens of thousands. This report has led to a lot of concern for people living close to this region.
Experts expect this sizable event will unfold because it’s happened before. But, the chances of this occurring within the next 25 to 30 years are relatively small. The last time there was a major earthquake in this region was Jan. 26, 1700. It was estimated to be an 8.7 to 9.2 magnitude quake that likely generated a giant tsunami that hit Japan. Tree ring data show trees were drowned and the forests were lowered along the coastline.
Geological evidence shows seven major events in the 3,500 years before the 1700 quake, perhaps about 500 years apart. Research from cores obtained from the seafloor indicate that there have been 41 major earthquakes in the past 10,000 years. In 2010, scientists predicted a risk of 37 percent that the region could see a magnitude 8 or higher earthquake within the next 50 years.
The Earth’s land is constantly moving. In the Northwest, the Juan De Fuca plate off the Northwest Coast is literally diving under the huge North American plate to the east, which is called subduction. This region extends about 620 miles from northern Vancouver Island to Cape Mendocino in California. This process has formed the Cascade Range and its volcanoes. The subduction is also creating stress in the rocks and over time, the rocks snap and can lead to what is called a megathrust earthquake.
Although the chances for a major earthquake in the near future may be small, there’s always a chance it could happen. It’s not a bad idea to be prepared for such an event as they often come without warning. Before coming to the Northwest, my wife and I lived in Vermont and were hit with a 5.1 earthquake near Burlington. Yes, it was quite a surprise indeed.