The magnitude 7.6 Kashmir earthquake of October 8, 2005 caused the deaths of more than 73,000 people, the greatest loss of life of any earthquake in the Indian subcontinent. It also was Pakistan's worst natural disaster of any kind, a source of alarm to the governments of Pakistan and India because both countries share the seismically-active and increasingly urban-populated Himalaya. Large, devastating earthquakes in the Himalaya are thought to be associated with the Himalayan basal decollement, the India-Asia plate boundary. Historic earthquakes in the past two centuries have ruptured this fault but have not reached the surface at the Himalayan thrust front. In contrast, surface rupture at the thrust front did occur in Nepal and northwest India approximately 900 and 600 years ago, respectively. In the northwestern Himalaya of Pakistan, it is unknown whether ruptures occur at the thrust front during plate-boundary earthquakes. The 2005 Kashmir earthquake occurred on a fault within the orogenic belt and not at the thrust front, which indicates that some of the India-Asia convergence in Pakistan is absorbed by internal faults. A second major unknown is how strain and convergence are partitioned between the internal faults and the frontal thrust fault systems. The Oregon State University and California State University, Northridge, research team are conducting a three-year research project with the goal of constraining the India-Asia plate boundary earthquake cycle in Pakistan in order to provide the first constraints on the earthquake recurrence and slip rate of active structures. These data represent a much-needed first step in seismic hazard characterization of faults threatening major population centers (Islamabad, Rawalpindi, and Peshawar have a combined population of approximately 6,000,000).
Plate boundary earthquakes in the Himalaya threaten an ever-increasing population across a region in harm's way that is likely to be widely affected by the next great Himalayan earthquake. Over forty million people live in the Ganges plain south of the Himalaya, and the Himalayan foothills are dotted by numerous cities ranging in size from about 500,000 to more than 2 million people. The nearly 80,000 deaths in Pakistan during the 2005 Kashmir earthquake emphasize the magnitude of the hazard associated with Himalayan earthquakes. Although Pakistan has had historic devastating earthquakes (1935 Quetta, 35,000 killed), the country as a whole is largely unprepared for future events and does not have a cadre of scientists trained in earthquake geology. In this project, the scientific team will determine the earthquake history of key active faults in Pakistan and simultaneously train Pakistani scientists in the techniques used widely around the world to constrain earthquake hazard in the field. The scientific contribution of this project will be a new understanding of how the India-Asia collision is manifested by earthquakes in the northwest Himalaya. The societal legacy of this project will be new information on probabilistic forecasting of large earthquakes threatening some of the major population centers, leading to improved building codes and disaster prevention, and a new generation of scientists trained in the modern techniques of earthquake science. These Pakistani earth scientists will be equipped to carry forward into the future a systematic characterization of seismic hazards and earthquake history of active faults in Pakistan.
This award was co-funded by NSF's Office of International Science and Engineering.
