WEST SALEM, IL - The number of aftershocks linked to last week's earthquake has grown to two dozen.
The U.S. Geological Survey says 24 aftershocks have been centered in Illinois since last week's 5.2 magnitude temblor with its epicenter near West Salem in Edwards County.
The latest aftershock, reported as a 2.1 magnitude, came about 8:30 am Wednesday, near Belmont. Two of the aftershocks measured at least a 4.0 magnitude.
Seismologists say aftershocks can continue for days, in some cases even months, depending on the region or the geology.
Many of the aftershocks go unnoticed by people without specialized measuring equipment.