MANKATO, Minn. (AP) _ Southern Minnesota residents are on edge after another
quarry blast from a nearby mining operation sent a barrage of rocks through a
neighborhood.

A blast at Jefferson Quarry sent chunks of limestone - some as large as bowling balls - flying into a Mankato neighborhood last week.

The city has suspended the quarry's blasting permit for the second time while
it investigates.

The limestone and sand mining operation set off more than 4,500 pounds of
explosives in April. The company says a 2.8 Richter scale earthquake occurred
less than 10 seconds after the blast.

U.S. Geological Survey scientists say it's unlikely the tremors occurred
naturally.

City and company officials say the quarry has considered closing at the end of
the year.