The March 12, 1934 earthquake
M6.6Hansel Valley, Utah
A magnitude 6.6 earthquake 5.3 miles deep, centred in Box Elder County. The strongest in Utah’s record since 1900, and the strongest within 50 miles in the catalogue, which runs from 1900. 5 aftershocks of magnitude 2.5 or more followed within 30 days.
The earthquake
- Magnitude
- 6.6
- moment magnitude (mw)
- Depth
- 5.3 mi
- 8.5 km below the surface
- Local time
- Monday, March 12, 1934
- 08:05 MST; 15:05 UTC
- In Utah’s record
- 1st
- strongest of 2,224 since 1900
USGS ANSS Comprehensive Earthquake Catalog, event uu19340312150548000 (“The 1934 Hansel Valley, Utah Earthquake”). The USGS event page carries the ShakeMap, felt reports and the official summary.
Aftershocks
Earthquakes of magnitude 2.5 or more within 20 miles of the epicentre in the 30 days after.
5
Aftershocks in 30 days
5.9
Largest aftershock, Mar 12, 1934 · its page
3
On the first day
0
In the 7 days before
- The search radius is the surface rupture length expected for an earthquake of this magnitude (Wells and Coppersmith, 1994), at least 20 and at most 600 miles, so a great earthquake's sequence is counted along its whole fault.
- Before the modern seismic networks of the 1970s many small aftershocks went unrecorded, so early sequences read short.
Counties and cities within 50 miles
Distance from the epicentre to each county boundary (zero when inside) and to each city centre.
Counties
- Box Elder CountyUT · inside
- Cassia CountyID · 25.8 mi
- Oneida CountyID · 25.8 mi
- Weber CountyUT · 36.4 mi
- Cache CountyUT · 38.5 mi
- Franklin CountyID · 42.4 mi
- Tooele CountyUT · 43.1 mi
- Davis CountyUT · 43.1 mi
- Power CountyID · 46.9 mi
Cities, largest first
- LoganUT · 49.5 mi
- West HavenUT · 49.4 mi
- North OgdenUT · 49.3 mi
- Brigham CityUT · 39.8 mi
- TremontonUT · 31.6 mi
- Pleasant ViewUT · 47.1 mi
- HyrumUT · 49.1 mi
Earthquakes around the epicentre
119 earthquakes of magnitude 3 or more within 50 miles of this epicentre since 1973.
USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.