Sandwich Fault Zone

The Sandwich Fault Zone is a fault zone that runs northwest from Oswego to Ogle County, transecting Lee County in Northern Illinois. The fault has generally not been active, although there was a minor earthquake in 2002, and another, slightly larger one, in 2010.^[1] It has a largely 400 to 600-foot vertical displacement, although parts can reach up to an 800-foot displacement, and is likely a configuration of several smaller faults, varying in both direction and displacement.^[2][3]