It’s not just about the magnitude. What made Afghanistan earthquake destructive was its depth

It was like any regular Sunday until it was not. A little short of midnight, residents of Afghanistan’s Kunar province woke up to find their houses shaking. For one resident, he could see the walls of his house cracking. “We were afraid that the walls would fall in on us,” said the resident as he fled his house along with his family members.

A 6.0-strong earthquake hit towns in the province of Kunar, near the city of Jalalabad, on Sunday night, killing some 800 people and injured more than 2,500 in eastern Afghanistan. Officials note that this number is expected to climb as many in the villages remained unaccounted for and rescuers continued to pull bodies from the rubble as all local hospitals declared a state of emergency.

The powerful quake has prompted the Taliban-led government for international aid, with countries such as India stepping up and despatching humanitarian assistance.

Experts note that the shallow depth of the quake is the reason behind the unprecedented damage and exceptionally high death toll. But here’s why.

Quake rattles Afghanistan

On Sunday, at 11.47 pm, a 6.0-magnitude quake hit Afghanistan’s mountainous eastern region with the United States Geological Survey (USGS) noting that its epicentre was merely 27 kilometres away from Jalalabad, the country’s fifth-largest city, in eastern Nangarhar province.

According to Kate Carey, the deputy head of the United Nations’ office of humanitarian affairs in Afghanistan, these four provinces — Nangarhar, Nuristan, Laghman and Kunar — are the worst affected by the quake. Tremors were also felt in neighbouring Pakistan across several districts of the northwestern border province of Khyber Pakhtunkhwa as well in as parts of Punjab Province, the Pakistan Meteorological Department said. No major damage or casualties were immediately reported in Pakistan, officials said.

The initial quake was followed by a number of large aftershocks; one with a magnitude of 4.5 and a depth of 10 km and the other measuring 5.2 at the same depth. These are thought to have caused further damage in Afghanistan.

The quake, according to authorities, have already claimed the lives of 800 people, as houses made of mud and stone were reduced to rubble. One survivor in the Maza Dara area of Nurgal told the Associated Press that he was woken by a deep boom that sounded like a storm approaching.

He ran to where his children were sleeping and rescued three of them. He was about to return to grab the rest of his family when the room fell on top of him. “I was half-buried and unable to get out,” he told the Associated Press. “My wife and two sons are dead, and my father is injured and in hospital with me. We were trapped for three to four hours until people from other areas arrived and pulled me out.” It felt like the whole mountain was shaking, he said.

Even Sanaullah, another resident of Kunar province, had a similar story to share. As he returned home on Monday — he was travelling at the time of the earthquake — he found that his house had been reduced to rubble and his brother had been killed alongside his five children. “It is the story of each and every house here,” he told The Guardian. “Everyone I know here has lost at least three to five family members.”

Search and rescue operations in quake-hit areas struggle

In the aftermath of the earthquake, the Taliban-led government has begun search and rescue operations but geography and politics complicate the matter.

The Taliban government’s chief spokesman, Zabihullah Mujahid, said on X, “Unfortunately, tonight’s earthquake has had human casualties and financial damages in some of our eastern provinces.

“Right now, local officials and residents are making all the efforts to rescue affected ones. Support teams from the capital and nearby provinces are also on their way. All available resources will be used for the rescue and relief of the people,” he added.

He later added that helicopters had been sent out to reach some areas as road travel was difficult. “There are some villages where the injured and dead haven’t been recovered from the rubble, so that’s why the numbers may increase,” he told journalists.

Later, Sharafat Zaman, spokesperson for the health ministry in Kabul, called for international aid to tackle the devastation wrought by the quake. “We need it because here lots of people lost their lives and houses,” he told Reuters.

As one resident from the Maza Dara area, said: “There are women and children pleading for help but there are no authorities present to help them,” he said. “Everyone is trapped under the rubble and we are helpless and seeing them dying in front of our eyes. There is no one here to help those buried and alive in the debris. There is no one here to remove the dead.”

The earthquake’s depth matters

But why is it that this 6.0-magnitude quake has caused so much death and damage? Experts point out that it’s the depth of this temblor that has exacerbated the situation.

Geological experts note that even if two earthquakes have the same magnitude, their depths can make a big difference in how much damage they cause and how strongly they are felt on the surface.

And in case of the Afghanistan one, it struck at a depth of about eight km, which seismologists consider shallow. In fact, experts have classified quakes based on their depth; there’s the shallow earthquakes, which occur between 0 and 70 km deep; then there’s the intermediate earthquakes that are 70 – 300 km deep; and deep earthquakes, 300 – 700 km deep.

According to them, a shallow quake causes more damage and is deadlier than deeper quakes. That’s because the energy created by a shallower quake has less distance to travel before reaching people and buildings. In comparison, in deeper earthquakes, much of the energy dissipates as it moves through layers of rock. By contrast, shallow ones release their energy closer to the ground, producing stronger shaking and greater damage in populated areas.

As Susan Hough, a USGS seismologist, noted the shaking is more intense from quakes that hit close to the surface like setting off “a bomb directly under a city”.

The worst earthquakes are shallow

In fact, some of the deadliest earthquakes in recent times have been shallow ones. For instance, in November 2022, a 5.6-magnitude quake struck near the Indonesian city of Cianjur in West Java, causing at least 268 deaths and damaged 22,000 buildings.

Seismologists noted that at 5.6, this earthquake was much smaller than many other earthquakes that have caused death and destruction in Indonesia over the past few decades. However, it was the depth of the quake that was the reason behind the damage; the earthquake’s epicentre was relatively shallow — approximately 9.97 km.

Another example of a shallow quake causing unprecedented damage is the Italy earthquake of 2016. The two quakes, which occurred one after another, killing nearly 300 people, were relatively shallow at a depth of nine km and the second at a depth of 10 km.

Even the Nepal earthquake of 2015, which killed over 8,000 people occurred at a depth of 8.2 km.

And Afghanistan’s four quakes of 2023 in the Herat province, which measured 6.3 each on the Richter Scale, were shallow quakes, around eight to 10 km deep.

With inputs from agencies

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