News
Low depth of epicentre brought massive damage
ISLAMABAD Oct 09 : The country's worst and strongest earthquake emerged somewhere 10 kilometres depth due to the movement of tectonic plates (individual sections that make up the Earth's surface like panels on a
football) 95 km north northeast of Islamabad, 115 km east southeast of Mingaora, 165 km north of Jhelum and 125 km west northwest Srinagar.The United States Geological Survey's Richter Scale measured it at 7.6 degrees while the Japanese Met office gauged it at 7.8 degrees. The epicentre located somewhere in Mansehra district (34.432°N and 73.537°E) brought its first and severest tremors at 8:50:38 in the morning. Experts believe the depth of earthquake's epicentre is key factors in its force and duration. Soon after the earthquake, the inhabitants of the mountainous region reported drawing muddy water from the fresh water wells, local press reports said on Sunday.
The region's worst earthquake was witnessed during the British colonial rule on May 30, 1935, when the Richter Scale techniques were rudimentary, but it could measure its intensity at 8.1 killing 30,000 plus inhabitants in the city.
Normally, origin or epicentre of earthquakes in Pakistan has been the Hindu Kash mountain ranges and that somewhere inside Afghanistan. The Saturday's earthquake has not only brought death and destruction to the northern Pakistan and entire Jammu and Kashmir state but also raised new scientific question as to whether a new tectonic activity has started in down below the Hazara division, endangering the populous cities of Peshawar to Lahore and putting at risk the civilian and defence industry in the seismological active zone.
Saturday's series of tremors have been the strongest and longest spell in the region's history. After the deadliest earthquake, country faced 16 aftershocks, the last of which recorded close the Iftar time, all originating from the same epicentre except for two coming from the depth of
20.3 km and 16.3 km while intensity varied from 5.2 to 6.3 at the Richter Scale, according to the US Geological Survey.English daily 'The News' spoke to a variety of experts across the country to find some insight into the widely rumour of the spell of aftershocks continuing for another two days, no one came up with a specific answer.
Despite high tech innovations in geology, prediction of an earthquake still remains a distant dream. Some successful studies have been conducted into post-earthquake.The Earth's crust is made up of 12 individual tectonic plates. Below the sea, they can measure 4km to 9.6km thick and under land this increases to 32km to 70.8km. Below the crust, radiation from the Earth's core heats the semi-molten mantle to temperatures of over 5000°C.
The first practical scale for measuring earthquakes was developed by geologist Charles Richter at the California Institute of Technology in 1930s, and the scale that most scientists use today still bears his name.
There are two ways in which scientists quantify the size of earthquakes--magnitude and intensity. Seismograph is another device that records earthquake activity and the measurement systems written to help interpret that data. Remember that the Richter scale is not a physical device, but a mathematical formula.Although the Geological Survey of Pakistan is there to provide the latest information on such issues, it did not come up to educate the masses in the disaster-like situation.
It website under subject "earthquake information" further links up the reader to a one-day seminar on earthquake preparedness but remains blanks about the technical aspects of the worst tremors in the country's history.
The Pakistan Met Department has divided the country into four zones based on expected ground acceleration. The areas surrounding Quetta, along the Makran coast and parts of the NWFP, along the Afghan border fall in Zone 4. The rest of the NWFP lies in Zone 3, with the exception of southern parts of this province, which lie in Zone 2. The remaining parts of the country's coast up to Karachi also lie in Zone 3. The remaining parts of the country lie in Zone 2. The major cities of Peshawar, Rawalpindi and Islamabad both sit in this zone. But they are regularly rattled by strong earthquakes from the north or from neighbouring Afghanistan. The upper western part of Balochistan and regions along the border with India lie in Zone 1. This zone also includes Lahore where there was serious damage caused by the 1905 Kangra earthquake in neighbouring India.
According to various expert studies conducted prior to October 8 earthquake, the most vulnerable parts of Pakistan lie in Balochstan province and around Quetta stretching to the Afghan border and western parts of Balochistan, which include the Makran coast up to the Iranian border. These regions could expect to have a maximum peak ground acceleration (PGA) ranging between 0.24g and 0.4g. Parts of northern Punjab could expect a maximum PGA ranging between 0.24g and 0.32g. Similar values of PGA could be expected in northern sections of the NWFP and around Karachi, in Sindh Province.
Maximum PGA values for the rest of the country do not fall below 0.8g. These values steadily decrease towards the Indian border. The region with the lowest maximum PGA is a region between Khangarh and Fort Abbas, along the international border with India.
According to the Geological Survey of Pakistan, the earthquake activity in Pakistan is mainly concentrated in the north and western sections of the country, along the boundary of the Indian plate and the Iranian and Afghan micro-plates.
The Chaman Fault runs along Pakistan's western frontier with Afghanistan from Kalat, in the northern Makran range, past Quetta and then on to Kabul, Afghanistan.
A fault also runs along the Makran coast and is believed to be of the same nature as the West Coast fault along the coast of Maharashtra, India. An active subduction zone exists off the Makran coast. The great 1945 earthquake was centred in this region. This zone forms the boundary between the Arabian and the Iranian micro-plate, where the former subducts or dives beneath the latter. Thrust zones run along the Kirthar, Sulaiman and Salt ranges. There are four faults in and around Karachi and other parts of deltaic Indus, and Makran coast.
The first is the Allah Bund fault that passes through Shahbundar, Jah, Pakistan Steel Mills, and runs through eastern parts of the city and ends near Cape Monz. This fault, in fact, has caused extensive damage in the past many centuries in the deltaic areas.
The destruction of Bhanbhor in the 13th century and damage to Shahbundar in
1896 were caused by this fault. The other one emanates from the Rann of Kutchh.The third one is the Pubb fault which ends into Arabian sea near Makran coast and the last one is located in the lower Dadu district near Surajani and falls in the vicinity of Karachi. Tsunamis or tidal waves have also affected the coast of Pakistan. The worst case was in 1945 when an earthquake of magnitude 7.9 struck the Makran coast; waves as high as 12 meters were reported.