More aftershocks shook part of the Midwest on Monday, three days after a magnitude 5.2 quake rattled nerves across the region. The US Geological Survey said a total of 22 aftershocks had been recorded since last week's tremor that was centered deep beneath the surface near West Salem, in southern Illinois. They included one just before 12:40 a.m. Monday that registered magnitude 4.0 and had its epicenter northwest of Mount Carmel. That tremor was initially reported as 4.5 but was downgraded during the day. The strongest aftershock registered magnitude 4.6 about 5Â½ hours after the original quake Friday morning. Friday's quake shook a wide area of the Midwest and caused minor damage.