Date: May 6, 1947

Location: Milwaukee, Wisconsin

Magnitude: 4.0

Milwaukee Sentinel, Wednesday, May 7, 1947, page 1.

Half-Second Shock Rocks Six Counties. Short Duration of Tremor Prevents Heavy Damage.

Milwaukee shook in the grip of its first recorded earthquake for half a second at 3:25 p. m. yesterday - and can thank its stars that the quake lasted no longer.

The giant tremors, which rocked buildings, knocked dishes off shelves and pictures off walls and put some pedestrians off balance, were felt in surrounding counties, too, but not as strongly.

Residents of Waukesha, Racine, Kenosha, Walworth and Ozaukee Counties reported they felt the vibration. Some said it was accompanied by a rumbling noise. No serious property damage resulted here or elsewhere, and the Milwaukee Gas Light Co. reported no breaks or trouble in the gas system.

After the shock was over, the city's undermanned telephone lines were clogged with calls from men and women wanting to know what had happened. Many thought there had been an explosion.

The Rev. Joseph Carroll, S.J., head of Marquette University's Physics Department, declared that the city had "a very narrow escape." "Very serious damage" might have resulted if the quake had continued a fraction of a minute more, Father Carroll said, with walls cracking, buildings toppling - particularly those on the filled in land on the lake front - and fires breaking out all over the city. The major quakes, he said, last about 40 seconds.

The exact duration of the quake here isn't known, because both pens of the university's seismograph recording device, were thrown off the machine after recording the sudden violent vibration for two-fifths of a second. That was because Milwaukee was in the very center of the quake area, Father Carroll explained, and no seismograph is equal to recording a quake that close to home.


The seismograph has recorded tremors from an average of 50 earthquakes a year in other parts of the world, Father Carroll said. These recordings are generally the only local effect, though some vibration was reported here in September, 1944, from a quake in Ontario. Yesterday's quake is the only one on record in Wisconsin, Father Carroll added, and the only one even rumored in the state before the days of the seismograph was a light one in the 1750s.

New water veins may have been opened up by yesterday's earthquake, bringing a new supply of water to wells throughout the county.

(A picture shows) Elmer Rexin of 3439 N. 51st St., maintenance engineer at the Nunn Bush Shoe Co., 2822 N. 5th St., examines the chart of a well depth recorder at the plant which supported that belief. The shaky line on the chart shows the start of tremors which shook the 750 foot well at the plant and the straight line the rise of the water level during and after the shock. The water went up about two feet.

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