[rwfromkansas]

Hmm....this page says the interval is 120 years between earthquakes greater than 6.5, and that the last one occurred 66 years ago.

http://www.seis.utah.edu/edservices/EES/WsatchFrontClock.shtml

Isn't there still a lot of time left, or is this info outdated based on recent discoveries?


Greater than 6.5
120 years
66 years

[Strategerist]

Eh, it's a bit over-simplified. It's different times for each segment; I was referring to the central segments immediately around SLC.

http://geology.utah.gov/online/pdf/pi-40.pdf

"These earthquakes took place on the fault's five central segments (Brigham City, Weber, Salt Lake City, Provo, and Nephi) and one distal segment (Levan). Collectively, the "composite recurrence interval," or how often a large earthquake has occurred on the central portion of the Wasatch fault, is approximately once every 350 years. The last large earthquake happened about 600 years ago on the Provo segment, and possibly earlier on the Nephi segment (although the starburst position indicates a carbon-dated event closer to 1,200 years ago, some researchers estimate an earthquake occurred as recently as 400 years ago on the Nephi segment)."


A PDF unfortunately...

[BagCamAddict]

As Strategerist says, those "averages" oversimplify things. It's the same as the "100-year Flood Plain" analogy...

If there is a so-called "100-year Flood" along a river in Iowa in 1996, then a bunch of people will assume it's safe to build a house next to the river in 1997 "because there won't be another flood like that for 99 more years."

The terms "100-year Flood" and "interval of 120 years" are both approximations and colloquial measurements of magnitude. In other words, you could have THREE "100-year floods" in the same season, or three in a row, or three in a 10-year period, etc... You could also have an earthquake greater than 6.5 at 66 years, 67 years, or 167 years.

If we knew how to predict these things with complete accuracy, they wouldn't be called natural disasters, they would be called "scheduled evacuation dates." :-)