Severe earthquake that struck near the city of Kathmandu in central Nepal on April 25, 2015. Several thousand people were killed; many thousands more were injured; and more than a half million structures in Kathmandu and other nearby towns were either damaged or destroyed. The earthquake was felt throughout central and eastern Nepal, much of theGanges River plain in northern India, and northwestern Bangladesh, as well as in the southern parts of the Plateau of Tibet and western Bhutan. The initial shock, which registered a moment magnitude of 7.8, struck shortly before noon local time (about 06:11 am Greenwich Mean Time). Itsepicentre was about 21 miles (34 km) east-southeast of Lamjung and 48 miles (77 km) northwest of Kathmandu, and its focus was 9.3 miles (about 15 km) underground. Two large aftershocks, with magnitudes 6.6 and 6.7, shook the region within one hour of the main quake, and several dozen smaller aftershocks occurred in the region during the succeeding days. On May 12 a magnitude-7.3 aftershock struck some 76 km (47 miles) east-northeast of Kathmandu, killing more than 100 people and injuring nearly 1,900.
The earthquake and its aftershocks were the result of thrust faulting (i.e., compression-driven fracturing) in the Indus-Yarlung suture zone, a thin east-west region spanning roughly the length of the Himalayan ranges. The earthquake relieved compressional pressure between the Eurasiantectonic plate and the Indian section of the Indo-Australian Plate, which subducts (underthrusts) the Eurasian Plate. Subduction in the Himalayas occurs at an average rate of 1.6–2 inches (4–5 cm) annually. Such tectonic activity adds more than 0.4 inch (1 cm) to the height of the Himalayan mountains every year.
The Himalayan region is one of the most seismically active in the world, but large earthquakes have occurred there infrequently. Before the 2015 temblor, the most recent large earthquake (that is, magnitude 6.0 or above) took place in 1988. That magnitude-6.9 event resulted in the deaths of 1,500 people. A magnitude-8.0 earthquake in 1934, however, killed approximately 10,600 people.
Initial reports of casualties following the early-morning earthquake put the death toll in the hundreds, but, as the day wore on, reports had the total number of fatalities surpassing 1,000 and nearing 1,900 by the end of the day. Within two weeks after the main quake occurred, rescue teams had reached all the remote villages in the earthquake zone, and a more-accurate picture of the earthquake’s human cost emerged. The deaths of more than 8,300 people (which included fatalities in nearby parts of India, China, and Bangladesh) were confirmed, with nearly 18,000 injured and some 2.8 million people displaced by the earthquake. One United Nations (UN) report mentioned that more than eight million people (more than one-fourth of Nepal’s population) were affected by the event and its aftermath.