A powerful earthquake of 7.5 magnitude centred in Afghanistan, has killed over 150 people. At least 135 people have died in Pakistan and over thousand are reported injured. The earthquake shook north India with tremors that lasted almost a minute.
An earthquake is a sudden vibration or trembling in the Earth. Earthquake motion is caused by the quick release of stored potential energy into the kinetic energy of motion.
The quake, which struck at 1:39 p.m., was centered in the Hindu Kush mountain range, about 28 miles southwest of the district of Jurm in Afghanistan and about 160 miles northeast of Kabul, the Afghan capital.
This is just a few hundred kilometres from the site of a 7.6 magnitude earthquake that struck in October 2005, killing more than 75,000 people and displacing some 3.5 million more, although that earthquake was much shallower.
31 people have died in Afghanistan. The death toll in Pakistan’s Khyber Pakhtunkhwa province and Federally Administered Tribal Areas (FATA) is 123, with five killed in Punjab, and four in Pakistan Occupied Kashmir, the newspaper Dawn reported. The Pakistan Army has been deployed for relief operations.
In India, massive tremors were felt in Delhi, Kashmir, Rajasthan, Himachal Pradesh, Uttarakhand, Haryana and Punjab. Hundreds rushed out of shaking buildings and remained on the streets for some time, fearing aftershocks.
Even at its revised magnitude of 7.5, this was a powerful tremor. Around the world only about 20 quakes each year, on average, measure greater than 7.0.
But its focus was deep – much further below the surface than the 7.8 quake which brought widespread destruction to eastern Nepal in April. That event was only 8km deep and was followed in early May by an aftershock with magnitude 7.3.
Similarly, the devastating 2005 Kashmir earthquake was magnitude 7.6 and just 26km deep. Today’s quake, at a depth of more than 200km, appears to have caused widespread but less severe ground shaking.
Landslides were reported in the mountainous Pakistani regions of Gilgit and Chitral, as boulders fell on to the roads, cutting off many areas. Damage was reported in more central parts of the country as well: In Punjab Province (Pak), at least 10 people were wounded when a school wall collapsed in the city of Sargodha.
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GEOLOGY OF THIS EARTHQUAKE
The October 26, 2015 M 7.5 earthquake near the Hindu Kush region of Afghanistan (SW of Jarm) occurred as the result of reverse faulting at intermediate depths, approximately 210 km below the Hindu Kush Range in northeastern Afghanistan.
Seismicity in the Himalaya dominantly results from the continental collision of the India and Eurasia plates, which are converging at a relative rate of 40-50 mm/yr. Northward underthrusting of India beneath Eurasia generates numerous earthquakes and consequently makes this area one of the most seismically hazardous regions on Earth.
The surface expression of the plate boundary is marked by the foothills of the north-south trending Sulaiman Range in the west, the Indo-Burmese Arc in the east and the east-west trending Himalaya Front in the north of India.
The India-Eurasia plate boundary is a diffuse boundary, which in the region near the north of India, lies within the limits of the Indus-Tsangpo (also called the Yarlung-Zangbo) Suture to the north and the Main Frontal Thrust to the south.
The Indus-Tsangpo Suture Zone is located roughly 200 km north of the Himalaya Front and is defined by an exposed ophiolite chain along its southern margin. The narrow (<200km) Himalaya Front includes numerous east-west trending, parallel structures. This region has the highest rates of seismicity and largest earthquakes in the Himalaya region, caused mainly by movement on thrust faults.
