<== Site Review (2009-01-04) ==>
USGS Earthquake Hazards Program
Wow, look at all the pretty mountains surrounding the Salt Lake Valley. I wonder how they got here!
Guess what? Salt Lake is smack dab in the middle of an earthquake zone. The mountains were pushed up relative to the valley floor by a continuing series of earthquakes.
Judging from the height of the Wasatch Mountains, Utah must had a large number of serious earthquakes in its past. For the site of the day, I've selected the U.S.G.S. Utah Seismic Activity page which monitors local earthquake activity. This page lists current and historical seismic activity in and around the beehive state.
The Earthquake Hazard map shows that Salt Lake City sits in an area with an elevated risk of earthquakes. The area is so active that it is not a question of if a major earthquake will happen in Salt Lake City, but when a major earthquake will happen. We are long over do.
The geology of the Salt Lake area is quite interesting. Salt Lake sits on the eastern edge of the Great Basin. The Great Basin is part of the North American Plate (Plate Tectonics). The Great Basin stretches from the Wasatch Mountains to the Sierra Nevada Mountains in Nevada. The Great Basin does not have an outlet to the sea, which is why there is a big salty lake sitting in the middle of the Salt Lake Valley.
The Great Basin is part of the North American plate. The area of the Great Basin is being pulled apart and twisted, these extensional and transformational forces caused the land in plate in the Great Basin to buckle ... producing a series of mountain ranges and valleys from the Wasatch Mountains westward.
Imagine the Oquirrh and Wasatch Mountains slowly being pulled apart. The valley floor will occasionally slip in relation to the mountain tops ... bam! an earthquake.
In 1983, a 6.9 magnitude earthquake hit a sparsely populated area in Idaho. After the quake, Mount Borah was 15 feet higher. There were only two lives lost in the quake. Of course, there were only a hundred or so people living near the quake.
There is a high probability that a major earthquake with hit the Wasatch Front in your lifetime. There usually is not any warning.