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  5 0 Not too personal at all! The Wasatch front is a real seismic hazard but it differs significantly from Seattle's. In Utah the predominant seismic hazard is from the range-bounding "normal" fault that runs all along the front and right through Salt Lake City. ("normal" here being geological jargon denoting a fault that is a dipping plane, with the block on top slipping down relative to the block on the bottom--like gravity was driving it.) Big normal faults create the beautiful mountains and valleys all across the Basin and Range, with the Sierra Nevada on the west and the Wasatch on the east moving ever so slowly apart. The Wasatch fault breaks in chunks that give rise to earthquakes in the M7+ range. Here's an image I stole from the USGS, showing the most recent breaks along the front according to geologists. The overall level of hazard is a bit less than that of Seattle. The USGS National Seismic Hazard Maps provide gobs of detail. Here's a quick overview in which reds are bad and greens good (as usual!) that gives you an intuitive feel for the distribution of hazard in the western US. Now this specific map represents a level of a specific frequency of ground shaking that can be expected with a probability of 2% in 50 years. This convoluted way of looking at things ends up being useful for planners, although it seems confusing to us mortals.  But think of it like a weather map showing the likelihood of strong rain, for example. You're more likely to get shook in Seattle over any 50 year period, then you are in Salt Lake. But both are pretty high. The difference in Seattle is diversity [Gee, who would have thought Seattle to be more diverse than Salt Lake City?]. The potential earthquake sources that contribute to Seattle's high hazard level include M9 megaquakes on the subduction interface out to the west of the city, deep earthquakes (like the 2001 Nisqually earthquake ) in the downgoing sea-floor slab, and crustal faults (like the Seattle Fault that runs right through the city). While the chance of an earthquake from any of the three sources is fairly low (Well, the Nisqually-type source seems to have a rather high recurrence rate, given very similar events in 1949 and 1965 ), they all conspire to form a fairly hefty hazard here. Paul Bodin answered in Earthquake! over 2 years ago | Report 2 comments by O my captain and O my captain… 0 0 I want to tell you just how much I'm enjoying this special feature Q&A on Questionland this week. Thank you SO much for participating! O my captain commented over 2 years ago | Report 0 0 When I lived a year in salt lake city, no one seemed to pay any attention to earthquake risk. I asked my boss, and his comment was, "Oh yeah, we're riddled with faults, but don't worry, if they slip, this old 18th century building will collapse around us and we'll all be wiped out." SERIOUSLY. O my captain commented about 1 year ago | Report Enter your comment or ask a new question New comments are not being accepted at this time.

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