The Wasatch fault zone does pose a significant seismic hazard but earthquakes on the WFZ are not nearly as regular as on the San Andreas. On this page [1] (sec

The Wasatch fault zone does pose a significant seismic hazard but earthquakes on the WFZ are not nearly as regular as on the San Andreas. On this page [1] (second picture, left side) is a figure showing the instances of known earthquakes along the fault through time; you can see that they're quite irregular, both in space and time. An updated compilation of this data [2, gated] has better accounting of the uncertainties and a fuller record, especially on the older end. In any case, it's clear that some of the fault zone seems to be 'overdue' but other segments, including the Weber and Provo segments, have had moderate earthquakes within the past ~500 years, which is a bit shorter than the median recurrence interval. The SLC segment on the other hand may have enough accumulated stress to cause a pretty significant earthquake. Note that it's really not clear to what extent faults rupture periodically; there are researchers who argue that the likelihood of an event is basically independent of the time since the last event (basically a Poisson distribution), those who argue for fairly regular events, and everything in between. It probably varies a lot from fault to fault and is more regular on big plate boundary faults like the San Andreas than on smaller (or slower-moving) intraplate faults like the Wasatch Fault. The real danger, both here and for the San Andreas system, is that an earthquake will break through the segment boundaries and cause a much, much larger earthquake. It's not been demonstrated that this is has happened on the Wasatch fault (there is one instance about 6000 years ago where this is possible within the data uncertainty) but this has happened in California in the 1906 S.F. and 1857 Fort Tejon earthquakes. Although this might not cause more displacement of the fault in any one location, it creates such a bigger swath of destruction that there are more opportunities for associated disasters (fires, floods from dams breaking, etc.) and make response much more difficult. It's also a bit outside my expertise but I think that for a long rupture, there is enough constructive interference of surface waves from the earthquake that ground shaking is much greater than is predicted from displacement at any point on the fault. [1]: http://michaelhaskinseportfolio.weebly.com/earthquake-hazards-along-the-wasatch-fault.html http://michaelhaskinseportfolio.weebly.com/earthquake-hazard... [2]: http://www.bssaonline.org/content/98/6/2918.short http://www.bssaonline.org/content/98/6/2918.short