Why are earthquakes so deadly in some countries and not others?

More than 1,000 people died after recent earthquake in Afghanistan, days after minor quake was in Sharjah went unnoticed

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Wednesday’s 5.9-magnitude earthquake in Afghanistan has, along with aftershocks, killed more than 1,000 people, making it the deadliest event of its kind in the country in two decades.

Poor infrastructure and services made dealing with the tragedy particularly difficult for the country’s Taliban authorities, who have appealed for international assistance.

A few days before the earthquake in Afghanistan, the UAE experienced a much smaller event, a 2.4-magnitude quake in Sharjah.

As reported by The National, the June 18 quake — which officials said was not felt by residents — is the latest in a series of infrequent and mostly small tremors felt in the UAE.

So why is Afghanistan — along with neighbours such as Pakistan — vulnerable to deadlier earthquakes?

How are earthquakes classified and what damage can they cause?

A key measure is the magnitude of the quake, which reflects the size of the waves the event produces.

The Richter scale classifies quakes between 1.0 and 2.9 as “micro”, 3.0 to 3.9 as “minor”, 4.0 to 4.9 as “light”, 5.0 to 5.9 as “moderate”, 6.0 to 6.9 as “strong”, 7.0 to 7.9 as “major” and 8.0 and above as “great”.

Micro earthquakes, such as the kind the UAE experienced this month, occur more than 100,000 times a year and are typically detected by local instruments — but not people.

The Afghanistan earthquake was at the upper end of the moderate category and there are between about 200 and 2,000 such events each year.

These usually cause damage only to poorly constructed buildings, which helps to explain the devastation seen in Afghanistan, as many houses and other buildings in the country are not built to survive earthquakes.

“There’s no reinforcement. There’s not even any cement [in some buildings],” said Peter Styles, professor emeritus of applied and environmental geophysics at Keele University in the UK, who has seen first-hand the damage earthquakes have caused in countries such as Pakistan.

“Unfortunately, there’s very little we can do in terms of stopping these earthquakes. The buildings fall down and you build them up again.”

By contrast, in the Gulf, building codes are more stringent, Mr Styles said, so even if an earthquake of a high magnitude were to occur, the consequences would not be as severe.

“If you have sufficient money, you can withstand a magnitude six without problems,” Mr Styles said.

Why does Afghanistan suffer more severe earthquakes?

To understand why Afghanistan, and neighbouring Pakistan, are at risk of earthquakes, it is necessary to look to India.

The earth has more than a dozen major tectonic plates and the area around Afghanistan lies close to the border of three of them — the Arabian Plate, the Indian Plate and the Eurasian Plate. The Indian Plate is moving north and colliding with the Eurasian Plate.

“India is trying to move northwards,” Mr Styles said. “It’s shaped like a gigantic wedge; it’s forcing its way into Asia. That’s why we have the Himalayas, the Hindu Kush [mountain ranges].

“These earthquakes are on the main Himalayan fault. [Afghanistan and Pakistan] are on a major tectonic boundary.”

The area that was hit is part of the Alpide Belt, which stretches all the way to the Atlantic and is one of the most seismically active regions in the world.

By contrast, the UAE's location means it is not as vulnerable to movements of tectonic plates.

“The Arabian Plate is mostly being pushed sideways because of the opening of the Red Sea. That’s a slightly different process,” Mr Styles said.

“Arabia was joined to Africa, although in the last 30 million years, Arabia has slid northwards.”

Jordan, Palestine, Israel and Syria are more likely than the UAE to experience tremors because they lie close to the border of the Arabian Plate and the African Plate. Both are migrating northwards, but the movement of the Arabian Plate is faster.

The UAE and surrounding states are “not anywhere near as vulnerable as even the western part of Saudi Arabia", Mr Styles said.

“Arabia and the Gulf states are slightly protected because the whole block is moving northwards,” he added.

Iran, however, lies in the region where the Arabian Plate and the Eurasian Plate meet, putting it at risk of earthquakes. Like Afghanistan, it is on the Alpide Belt.

This month, Iran experienced a 5.9-magnitude quake, which was felt in the Emirates.

Updated: June 25, 2022, 8:29 AM
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