epicenter on the Alavar thrust fault on the slopes of the Lesser Caucasus mountains north of Mount Aragats. The mainshock produced surface rupture and propagated to the west with a separate strike-slip sub-event occurring two seconds later that propagated to the southeast. Going westward the fault split into two branches, a north-dipping reverse fault (north branch) and a right slip fault (south branch), but neither produced surface rupture. A total of five sub-events occurred in the first eleven seconds and an aftershock measuring 5.8 (local magnitude) occurred four minutes and twenty seconds later. Damage Some of the strongest shaking occurred in industrial areas with chemical and food processing plants, electrical substations, and power plants. The Metsamor Nuclear Power Plant, around from the epicenter, experienced only minor shaking and no damage occurred there, but was eventually closed for a period of six years due to vulnerability concerns. It was reopened in 1995 in order to relieve Armenia of a major energy blockade imposed by Azerbaijan due to the First Nagorno-Karabakh War, amid criticism of lack of training, political instability in the Caucasus region, and accusations that the plant was of inadequate design. Many buildings did not hold up to the shaking of the earthquake and those that did collapse often lacked any survival space, but lack of effective medical care and poor planning also contributed to the substantial scope of the disaster. Buildings that didn't collapse featured well-maintained masonry and skeletal components that were joined together adequately in a way that allowed for the building to resist seismic waves. Most bridges and tunnels and other public infrastructure withstood the earthquake but hospitals did not fare well. Most collapsed, killing two-thirds of their doctors, destroying equipment and medicine, and reducing the capacity to handle the critical medical needs in the region. The Soviet news media and government officials soon began to discuss the apparent substandard construction styles that had caused so many of Armenia's buildings to collapse. Gorbachev, in a TV interview several weeks after his expedited return from New York City, said that the concrete blocks had been built with more than enough sand but too little concrete, and suggested that the concrete had been stolen. Leonid Bibin, deputy chairman of the state building committee, stated that many newer homes collapsed as well and that he was beginning an investigation into the matter and that criminal charges would be brought. The