Posted Thursday --- January 31, 2008

UW-Madison geologists record ice quake near Lake Mendota

MADISON, Wis. (AP) -- The shaking some University of Wisconsin-Madison staffers and others felt Thursday afternoon near Lake Mendota was most likely an ice quake.

UW-Madison geologists say they recorded a tremor at 12:50 p.m. that last a few seconds.

UW-Madison seismologist Cliff Thurber says ice quakes are caused by large shifts in ice and often triggered by drastic temperature changes -- similar to those seen in the past few days.

Thurber says a fresh break or pressure ridge may be visible on Lake Mendota after Thursday's event.

Ice quakes are usually accompanied by loud cracking noises, and the university says a number of people called UW police and facilities workers Thursday asking about the rumbling.

AP