Pakistan in the most active quake zone, says US Geological Survey

Published October 27, 2015
Peshawar: An injured boy is being treated at a hospital.—AP
Peshawar: An injured boy is being treated at a hospital.—AP

WASHINGTON: A reverse faulting at immediate depths about 210 km below the Hindu Kush Range in north-eastern Afghanistan caused Monday’s earthquake in the Pak-Afghan region, according to the US Geological Survey.

In a report on the earthquake and its causes, the USGS said the rupture occurred on either a near-vertical reverse fault or a shallowly dipping thrust fault. At the latitude of the earthquake, the Sub-continent moves northward and collides with Eurasia at a velocity of about 37 millimetres per year.

Active faults and their resultant earthquakes in northern Pakistan and adjacent parts of India and Afghanistan are the direct result of convergence between the South Asian and Eurasia plates.

This collision causes an uplift that produces the highest mountain peaks in the world like the Himalayas, the Karakoram, the Pamir and the Hindu Kush ranges.

LANDI KOTAL: People take part in the rescue work after a house was destroyed by the earthquake.—Online
LANDI KOTAL: People take part in the rescue work after a house was destroyed by the earthquake.—Online

Earthquakes such as this event, with focal depths between 70 and 300 km, are commonly termed “intermediate-depth” earthquakes. Intermediate-depth earthquakes represent deformation within sub-ducted lithosphere rather than at the shallow plate interfaces between sub-ducting and overriding tectonic plates.


Active faults and resultant earthquakes in Pakistan, India and Afghanistan are the result of convergence between the S. Asian and Eurasia plates


They typically cause less damage on the ground surface above their foci than is the case with similar magnitude shallow-focus earthquakes, but large intermediate-depth earthquakes may be felt at great distance from their epicenters.

Pakistan is located in the Indus-Tsangpo Suture Zone, which is roughly 200 km north of the Himalaya Front and is defined by an exposed ophiolite chain along its southern margin. This region has the highest rates of seismicity and largest earthquakes in the Himalaya region, caused mainly by movement on thrust faults.

Karakoram Highway: People remove boulders blocking the Karakoram Highway in Kohistan after a landslide caused by the earthquake.—Hussain Nagri
Karakoram Highway: People remove boulders blocking the Karakoram Highway in Kohistan after a landslide caused by the earthquake.—Hussain Nagri

Examples of significant earthquakes, in this densely populated region, caused by reverse slip movement include an 8.1 magnitude earthquake in Bihar, the 1905 7.5 magnitude Kangra and the 2005 7.6 magnitude Kashmir earthquakes.

The latter two resulted in the highest death tolls for Himalaya earthquakes seen to date, together killing over 100,000 people and leaving millions homeless. The largest instrumentally recorded Himalaya earthquake occurred on Aug 15, 1950, in Assam, eastern India. This 8.6 magnitude right-lateral, strike-slip, earthquake was widely felt over a broad area of central Asia, causing extensive damage to villages in the epicentral region.

PESHAWAR: A water tank of a house was jolted and displaced in the Ganj area.—APP
PESHAWAR: A water tank of a house was jolted and displaced in the Ganj area.—APP

Along the western margin of the Tibetan Plateau, in the vicinity of south-eastern Afghanistan and western Pakistan, the South Asian plate translates obliquely relative to the Eurasia plate, resulting in a complex fold-and-thrust belt known as the Sulaiman Range. Faulting in this region includes strike-slip, reverse-slip and oblique-slip motion and often results in shallow, destructive earthquakes.

The May 30,1935, 7.6 magnitude Quetta earthquake, which occurred in the Sulaiman Range in Pakistan, killed between 30,000 and 60,000 people.

Published in Dawn, October 27th, 2015

On a mobile phone? Get the Dawn Mobile App: Apple Store | Google Play

Opinion

The sixth wave

The sixth wave

PCR testing has drastically gone down in Pakistan and our disease surveillance system needs much more strengthening.

Editorial

Udaipur killing
Updated 01 Jul, 2022

Udaipur killing

The crime committed in Udaipur did not happen in a vacuum.
Unacceptable demand
Updated 01 Jul, 2022

Unacceptable demand

Negotiating with extremists is tricky; no peace treaty with them has lasted beyond a few months.
Tough times ahead
01 Jul, 2022

Tough times ahead

THE finance ministry’s projection of 15pc inflation, much higher than the targeted rate of 11.5pc, during the new...
More ‘prior actions’
Updated 30 Jun, 2022

More ‘prior actions’

It is crucial that the IMF reconsiders its stance and releases the funds at the earliest to calm uneasy markets.
Growing power crisis
30 Jun, 2022

Growing power crisis

THE country’s escalating power crisis risks exacerbating the law-and-order situation as people take to the streets...
Attack on polio team
30 Jun, 2022

Attack on polio team

THE threat of deadly violence never seems to diminish for health workers and police officials involved in...