News releases

Jan. 31, 2008

To: Editors/News Directors
From: Jill Sakai (608) 262-9772. sakai@wisc.edu
Subject: TIP/ICE QUAKE

The shaking felt this afternoon in areas near Lake Mendota was most likely an ice quake, according to University of Wisconsin-Madison geologists. A tremor was recorded by a geology department seismometer at 12:50 p.m. today and lasted approximately two or three seconds.

The event was very localized and did not have the hallmarks of an earthquake, but it did grab the attention of employees in lakeshore buildings. Dozens of staff had called either UW Police of facilities staff to inquire about the rumbling disturbance.

Ice quakes, usually accompanied by loud cracking noises, are caused by large shifts in ice and are most commonly triggered by drastic temperature changes, similar to those of the past few days, says UW-Madison seismologist Cliff Thurber. Based on the size of today's event, he says a fresh break or pressure ridge may be visible on Lake Mendota.

Thurber is available for media comment on today's ice quake and can be reached at (608) 262-6027 or thurber@geology.wisc.edu.