Demolition crews are shaking up downtown Salt Lake City, but not enough to register on the Richter scale.

The University of Utah Seismograph Stations receive periodic calls from business people curious if razing the ZCMI Center rises to earthquake magnitude. Most are workers in multi-story towers like the LDS Church Office Building across the street.

"We haven't had it register as an event," said Mark Hale, a U. earthquake information specialist. "We have seen something that could correspond on one station nearby. Whether it's the construction or quarry activity, it's hard to tell."

The U. has seismic recording instruments around the city center, the closest being about 1.5 miles away.

Tenants in buildings surrounding the nearly demolished ZCMI Center mall feel some shaking on an almost daily basis, especially those on higher floors. The mall and other buildings are being torn down to make way for the City Creek Center, a shopping, housing and office development.

Hale said the downtown activity isn't big enough and doesn't have a high enough frequency to travel to the nearest seismograph stations. Also, the city is built on the soft deposits of ancient Lake Bonneville. "That just sucks up the energy," he said.

The U. detected a small seismic signal when the 20-story Key Bank tower was imploded in August.