KARACHI, Dec 19 The seismicity of Pakistan is characterised by major earthquakes with a steadily increasing vulnerability of its northern and south-western regions. Unfortunately, the seismic awareness of these regions is still low.

These facts were highlighted in a report, Seismic Hazard Analysis and Zonation for Pakistan, Azad Jammu and Kashmir, prepared by the Pakistan Meteorological Department (PMD) and Norsar (Norwegian Seismic Array) in 2007.

The objective of the study was to conduct a seismic hazard investigation that covered all of Pakistan. The research contains details of design codes and seismic hazard maps that are designed to assist in the risk mitigation by providing a general seismic hazard framework.

For hazard assessment, the study region was divided into 19 seismic zones. The division was based on the seismicity, geology, source mechanism and the stress direction of the region.

According to the report, Pakistan is situated in a highly seismically active region which has experienced many disastrous earthquakes in the past. Some of the major quakes over the last 100 years include the 1945 Makran coast earthquake measured slightly above 8.0 on the Richter scale, the Machh earthquake recorded in August 1931, the 1935 Quetta quake at a magnitude of 7.3 on the Richter scale, the 1974 Pattan earthquake of 7.4 magnitude and the 2005 Muzaffarabad earthquake measured 7.6 on the Richter scale.

“The increasing population in the earthquake-prone cities is a major reason why the vulnerability to earthquakes is also increasing. It is globally realized that poorly-constructed buildings and houses are the main reason for the large number of victims due to earthquakes,” it says.

The mountains, notably Hindukush, Pamir and Karakorum, are characterised by deep and concentrated seismicity through which significant seismic energy is released every year. Seismically, the Hindukush-Pamir region is one of the most active regions in the world. The region generates very large earthquakes occurring down to 300km depth, which are also felt in Pakistan, the report adds.

In the light of historical data, the report says that there are five zones of high seismic activity in Pakistan. They are the Hindu Kush region, northern areas of Pakistan and Kashmir, north-western part of Balochistan, the coastal areas of Pakistan (near Makran region) and the south-eastern corner of Pakistan (Runn of Kutch).

Giving a brief history of the earthquakes of high magnitudes in the region, the report says that Quetta has been hit by earthquakes of magnitudes ranging between 8 and 9 on the Richter scale in 1888, 1893, 1900 and 1935. The areas surrounding Peshawar have been hit by quakes measuring 7 to 8 on the Richter scale in 1868, 1875 and 1878. Runn of Kuch was hit with an intensity of 7 and 10 on the Richter scale in 1819 and in 1845, respectively. Similarly, the Kashmir areas were hit by quakes with intensities ranging between 9 and 10 on the Richter scale in 1828, 1871 and twice in 1885.

All of these seismic events within the boundaries of Pakistan or near have been devastating, causing extensive damage and loss of life.

About the tsunamigenic zones in the Indian Ocean, the report refers to historical data and states that there is Sunda subduction zone in the east and Makran subduction zone in the northwest of Indian Ocean where three tsunamis had occurred. Generally, the seismicity of Pakistan is considered to be shallow and intermediate depths.

Summing up the seismic hazard results, the report states that Kashmir, Hazara and Quetta regions have a relatively high seismic potential. A high hazard level in the north, northeast, northwest and southwest of Pakistan suggests that many significant quakes have taken place there and more damaging earthquakes are expected in these regions.

The study consists of a long list of earthquakes that have occurred right from 25A.D. to 1905A.D. as well as the details of the largest earthquakes that include the Kangra earthquake that destroyed Lahore in 1905. That quake is one of the four great Himalayan earthquakes to have occurred in the past 200 years.

Explaining the creation of mountains, the study states that the Indian subcontinent has been colliding with the Eurosian subcontinent over the last 30 year to 40 years. As a result of the continent-to-continent collision in the Himalayas, the highest mountains in the world have been created, still being uplifted more rapidly than any other mountain chain.

The study, the result of three-year cooperation between PMD and Norsar, was conducted by Zahid Rafi, Ameer Hyder Leghari, Dr Conard Lindholm, Dr Hilmar Bungum and Dr Dominik Lang.