The 6 May 1947 Milwaukee, Wisconsin, earthquake

Seismological Research Letters



The State of Wisconsin is not known for earthquake activity. The authoritative public‐facing U.S. Geological Survey Comprehensive Catalog of earthquakes includes only three small (magnitude < 2) earthquakes in the state, all instrumentally recorded. Although other catalogs include more events in Wisconsin, experience has shown that many types of events, such as explosions and cryoseisms, have made their way into earthquake catalogs in this region. In this short report, I summarize available information about an earthquake that was felt in eastern Wisconsin at 15:27 local time on 6 May 1947. As what appears to be the largest historical earthquake in the State of Wisconsin, it is of public interest, its modest size notwithstanding. It appears that no useful instrumental records exist, due in part to a teleseismic event that occurred approximately 3 min later, generating surface waves that were recorded on early long‐period instruments in the region. Instrumental data may exist for this event but have not been found. Comparing the felt area with information from recent earthquakes in the region, I estimate an intensity magnitude of 3.8 for the event, with a subjectively estimated uncertainty range 3.5–4.1. Relatively strong effects, including reports of broken dishes in Milwaukee, and shaking described as short but especially sharp, suggest that the event may have been among the sprinkling of shallow earthquakes now known to occur in the upper Great Lakes region.

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Publication type Article
Publication Subtype Journal Article
Title The 6 May 1947 Milwaukee, Wisconsin, earthquake
Series title Seismological Research Letters
DOI 10.1785/0220210150
Volume 93
Issue 1
Year Published 2022
Language English
Publisher Seismological Society of America
Contributing office(s) Earthquake Science Center
Description 11 p.
First page 402
Last page 412
Country United States
State Wisconsin
City Milwaukee
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