Abstract

On September 2, 1994, a mbLg 3.4 (USGS) earthquake occurred in central Michigan at 21:23:10 UTC. Relocation of the epicenter utilizing regional arrivals and consideration of macroseismic effects yields an epicenter of 42.57 ± 0.05°N, 84.64 ± 0.04°W. The focal depth is shallow, 10–15 km based on macroseismic effects. The felt area extended from Owosso and Portland in the north to south of Bellevue. Detailed macroseismic observations were obtained through requests in the local media and spot surveys in selected portions of the region; a maximum MM intensity of V was obtained in a band between Potterville and Eaton Rapids. The greater Lansing area was intensity III–IV, with elevated intensities along the Grand River and on glacial moraines. The limits of the isoseismal map of the event may be controlled in part by the population density in the region and the area covered by the local media. Many observers reported two shocks. The cause of the event remains undetermined, but may be due to a hypothetical northwest-striking basement fault associated with the Lucas-Monroe fault. In this event, left-lateral strike-slip motion is likely.

First Page Preview

First page PDF preview
You do not currently have access to this article.