The 1886 Charleston earthquake occurred about 9:50 p.m. local time August 31. It caused 60 deaths and $5–6 million ($ million in ) in damage to 2,000 buildings in the Southeastern United States. It is one of the most powerful and damaging earthquakes to hit the East Coast of the United States. Scientists have classified it as an intraplate earthquake, and said that it had an estimated moment magnitude of 6.9–7.3 and a maximum Mercalli intensity of X (Extreme). Very little to no historical earthquake activity had occurred in this region, which is unusual for any seismic area. Earthquake The shock was felt as far away as Boston, Massachusetts, to the north, Chicago, Illinois, and Milwaukee, Wisconsin, to the northwest, New Orleans, Louisiana, to the west, and across water to Cuba to the south, and Bermuda to the east. The earthquake was so severe that outside the immediate area, there was speculation that the Florida peninsula had broken away from North America. There were at least 60 fatalities. Sand boils were common throughout the affected area due to soil liquefaction. Aftershocks continued to be felt for weeks after the event. Minor earthquake activity that still continues in the area in the early 21st century may be a continuation of aftershocks. With the development of earthquake studies and technology, this event has been extensively studied as an example of an intraplate earthquake. It is believed to have occurred on faults formed during the break-up of Pangaea. Similar faults are found all along the east coast of North America. It is thought that such ancient faults remain active from forces exerted on them by present-day motions of the North American Plate. The exact mechanisms of intraplate earthquakes are a subject of much ongoing research. Damage Building damage Within the city, many of the buildings sustained damage; some had to be torn down and rebuilt. The most prominent damage was done to buildings constructed out of brick, amounting to 81% of building damage. Buildings that had a wood frame suffered significantly less damage. Another factor that affected the percent of buildings destroyed was what kind of ground these buildings were built on. Buildings constructed on made ground were significantly more likely to be damaged than buildings constructed on solid ground; however, this relationship only occurred in wood-frame buildings, with 14% of wood-frame buildings built on made ground sustaining damages, compared to 0.5% of