1975 Morris earthquake
| UTC time | ?? |
|---|---|
| Magnitude | 4.6 (Richter scale)[1] |
| Areas affected | Vereinigte Staaten |
The 1975 Morris earthquake occurred in Morris, Minnesota, on July 9, 1975 at 14:54:15 UTC, or 9:54 a.m.[2] The strongest instrumentally recorded rupture in the history of the state, it registered at magnitude 4.6 on the Richter scale. It was the first earthquake to be recorded on any seismic instrument in the state since 1917[citation needed]. Tremors were felt over much of Minnesota, northern Iowa, and the eastern Dakotas.
Setting
Minnesota is not a very tectonically active state; however, there is at least one fault zone in it, the Great Lakes Tectonic Zone, stretching from Big Stone County and Traverse County to Duluth.[2] Seventeen earthquakes have occurred along the fault, the two largest being the Morris quake and the Staples event of 1917. However, plotting of the earthquakes suggests that there may be another hidden fault in the state somewhat adjacent to it.[3]
Damage
The earthquake caused moderate damage, and was defined as intensity VI on the Mercalli scale. Minor damage to walls and basement foundations was reported around the epicenter in Stevens County. Damage consisted of cracked plaster, falling items and pictures being knocked off walls. The quake also cracked the foundations of two homes on East Fifth Street in Morris. Many reports included extremely loud "bangs" and "explosions". These sounds lead to one man thinking that a nearby gas plant had exploded.[4] If the earthquake had occurred elsewhere, however, it may have caused a larger amount of damage.[5]
References
- ^ "Historic Earthquakes: Western Minnesota". USGS. July 16, 2008. Archived from the original on 9 January 2009. Retrieved December 19, 2008.
{{cite web}}: Unknown parameter|deadurl=ignored (|url-status=suggested) (help) - ^ a b Tom Cherveny. "Region's earthquake stories sought for educational project". University of Minnesota Morris. Retrieved December 19, 2008.
- ^ Newspaper contributors (June 17, 1993). "Background on fault . . ". Morris Tribune. Retrieved December 19, 2008.
{{cite web}}:|author=has generic name (help) - ^ Newspaper contributors (July 10, 1975). "Quake Brings Mixed Reactions Locally". West Central Daily Tribune. Retrieved December 19, 2008.
{{cite news}}:|author=has generic name (help) - ^ Morris Tribune contributors (July 10, 1975). "Earthquake Shock Felt In Area". Morris Tribune. Retrieved December 19, 2008.
{{cite news}}:|author=has generic name (help)