The 1555 Kashmir earthquake occurred at around midnight in the month of Ashvin in the Hindu calendar, or September in the Gregorian calendar, although the exact day of occurrence is not known. The earthquake seriously impacted the Kashmir Valley in present-day Pakistan and northwestern India. A moment magnitude () of 7.6 to 8.0 and Modified Mercalli intensity of XII (Extreme) has been estimated for the earthquake. Thought to be one of the most destructive in the Kashmir Valley, the earthquake caused serious widespread damage and ground effects, killing an estimated 600–60,000 individuals.
Tectonic setting
Northern Pakistan and India are situated at the corner of an active destructive plate boundary that separates the Indian Plate from the Eurasian Plate. The boundary is defined along the Main Himalayan Thrust where the Indian Plate is colliding with the Eurasian Plate. The slightly oblique convergence occurs at a rate of 17 ± 2 mm/yr along the Main Himalayan Thrust while the nearby Karakoram fault system accommodates right-lateral strike-slip movement at 5 ± 2 mm/yr.
The high convergence rate means many of the plate boundary faults are accommodating strain while locked, frequently releasing them in moderate-sized earthquakes, and sometimes in very large events. The occurrence of large earthquakes makes the Kashmir region vulnerable to deadly earthquakes.
Earthquake
The earthquake is thought to have been associated with a rupture on an active thrust fault that forms part of the plate boundary of the Kashmir Himalayas. Until recently, the source fault and possible surface ruptures of the earthquake have yet to be identified due to the lack of information of the event, in addition to the paleoseismicity of the region is poorly studied. The Main Frontal Thrust, Medlicott-Wadia (Riasi) Thrust, as well as the Kashmir Basin Fault (then the Balapur Fault) has been proposed as the seismogenic structure responsible for the earthquake.
The Medlicott-Wadia Thrust is expressed on the surface as two branching fault structures; the Scorpion and Rain faults. Paleoseismic studies have identified three large earthquakes on the Rain Fault, and two on the Scorpion Fault in the past 3,500 years. An account in Persian describing a destructive earthquake in 1250 BC corresponded to the oldest event which was dated at 1661 BC and 929 BC. The 1250 BC earthquake produced several meters of slip at the surface. Another earthquake occurred between 1118 BC and 929 BC with less than 1 meter of maximum slip. The Rain Fault may have ruptured in one or two earthquakes sometime between 1110 BC and 660 AD, and is possible that the two faults were involved in an earthquake in approximately 1000 BC. Persian and Sanskrit records also corresponded well with two earthquakes on the Rain Fault dated between 660 AD and 1470 AD.
The most recent paleoearthquake rupture is dated at 1470 AD or later. Large colluvial wedges associated with the rupture suggest the event caused high intensity shaking at the surface. The date of the rupture might suggest it was associated with the 1555 AD earthquake.
An earlier trenching survey conducted at the Chandigarh Fault near the Main Frontal Thrust also found a surface rupture that likely formed in 1426 to 1700 AD. This surface rupture could correspond to the 1555 AD earthquake which is had an estimated rupture length of 150 km.
Future hazard
In the wake of the 2005 Kashmir earthquake, much attention has been given to the Kashmir region in understanding the earthquake tectonics and assessing the seismic risk. The 1555 earthquake rupture is located roughly between that of the 2005 and 1905 Kangra earthquakes. No major seismic events have occurred since the 1555 earthquake in the 250-km-long Kashmir seismic gap on the Main Himalayan plate boundary fault. With a slip rate of 16 mm/yr, the accumulated slip since 1555 is estimated at 7.4 meters. If the 1555 earthquake released all the elastic energy accumulated since the previous earthquake, and fresh accumulation of stress began after the 1555 event, the next large earthquake could be as large as 7.8 .