2012 Chicago earthquake

The 2012 Chicago earthquake was a magnitude 7.2 earthquake that occured on March 12, 2012, at 10:11 AM local time. The quake's epicenter was located beneath downtown Chicago, centered on the fault later known as the Chicago Fault, one that had lain dormant since the end of the Ice Age.

History
The previous day, minor foreshocks were recorded by the USGS, but most were too small to be felt, and as such were only recorded by local seismographs. Stress on the Chicago Fault had been building since the 1999 earthquake, and even more so since a 5.4 earthquake in the Wabash Seismic Zone in 2008. Since the afternoon of the 10th, hundreds across the metro area had reported broken plumbing systems, which was caused by several of the foreshocks cracking open sewage and water lines underground; though the city power grid somehow escaped the damage from these foreshocks. The last foreshock, a 4.4, finally strained sections of the power grid beyond their endurance, collapsing the sections in North Chicago, West Town, Wicker and Lincoln Parks, North Center, Ravenswood, Edgewater, and Naperville, leaving thousands in the metro area without power around 9:16 PM on the 11th. Forty minutes later, service on the O'Hare Blue near the Kennedy Expressway and O'Hare itself was shut down when a small surface crack separated the rails, making use of the train impossible. Around the same time, the Loop Red Line was also shut down when another small surface crack dropped one of the track supports over a foot at the intersection of West Van Buren and South Wells.

Effects
Shaking was felt as far away as Des Moines, and the Canadian town of Blind River, Ontario. Shattered glass panes rained to the streets, killing hundreds. Every building in the city and throughout the metro area suffered damage; even both towers of the Chicago World Trade Center, the Chicago Spire, the Sears Tower, the Aon Center, and the John Hancock Center; whose foundation cracked and thereby tilted the building one foot to the southwest. Nearly 90 percent of the Art Deco skyscrapers and buildings in the city were destroyed, though all skyscrapers and most buildings built after 1950 survived, though they suffered heavy damage. Most notably, the CNA Center was destroyed when the McCormick Building and the Metropolitan Tower on the Park toppled into it. The Chase Tower was also toppled when the Inland Steel Building crashed into its foundation and lower floors, destabilizing an already weakened structure. Later, it was discovered that the quake had weakened sections of the crust in the Great Lakes region, allowing mantle plumes to 'punch' through these weak points, thus forming the first of the Great Lakes volcanoes.