How strong is a magnitude-7.8 quake?

Seismologists fear the quake hit a densely populated area of ​​southeastern Turkey and could be felt as far away as Israel and Cyprus. Authorities in Syria and Turkey say at least 200 people have been killed and expect the number to rise.

The quake, which struck at 4:17 a.m., according to the United States Geological Survey, was measured at a magnitude of 7.8. Earthquakes can be much stronger, experts say, but what’s more important than numerical magnitude is the relative magnitude associated with location — whether many people live nearby — and depth or whether one whether the earthquake is shallow enough to affect a large area.

In a report released about 30 minutes after the quake, experts at the USGS said there was a 34% chance of 100 to 1,000 deaths and a 31% chance of 1,000 to 10,000. dead.

“Wide scale damage is possible and disaster is likely to be widespread,” the report said. It estimated economic losses of up to 1% of Turkey’s gross domestic product.

Januka Attanayake, a seismologist at the University of Melbourne, Australia, said the energy released by the quake was equivalent to about 32 petajoules, enough to power New York City for more than four days.

“Energy-wise, a magnitude of 7.8 occurs 708 times stronger than a magnitude of 5.9,” he said, citing the Melbourne, Australia, earthquake in 2021, in which the The city suffered some minor damage.

The strength of an earthquake is measured on a scale known as the local magnitude scale. An earlier version is known as the Richter scale. It’s a logarithmic scale: With each integer increase, the amount of energy released by an earthquake increases by about 32 times.

But the potential damage of an earthquake depends on more than just its magnitude, with the population density of a given area as well as the shallowness of the epicenter both contributing to the extent of devastation, with A shallower earthquake is likely to cause more damage. This is about 10 miles deep.

Another important factor is the construction quality of the buildings in the area. The USGS report notes: “Residents in this area live in structures that are extremely susceptible to earthquake tremors, although some load-bearing structures exist,” the USGS report notes. noted and added: “The main types of vulnerable buildings are non-reinforced bricks and low-rise non-plastic concrete frames with construction buffers.”

In a Twitter post, USGS seismologist Susan Hough said the quake, while not the strongest the world has seen in recent decades, poses a particularly dangerous risk. dangerous due to its location and shallow depth.

At the bottom end of the scale, a magnitude 1 earthquake would be a micro-earthquake that is barely perceptible to humans. A magnitude 7 earthquake has been described by seismologists as having “the energy equivalent of about 32 atomic bombs dropped on Hiroshima”, as Renato Solidum, director of the Philippine Institute of Volcanology and Seismology , said. The era of 2013.

With a magnitude of 7.8, the earthquake in Turkey is classified as a “major” earthquake. Other earthquakes of similar magnitude included an earthquake in 2013 in Pakistanof which about 825 people died, and the April 2015 earthquake in Nepal, when nearly 9,000 people died.

Dr Attanayake, a seismologist in Melbourne, said the quake appeared to be one of a series. A fault line about 1,500 kilometers, or 930 miles, that divides the Eurasian Plate to the north from the Anatolian Plate to the south, has generated several earthquakes of magnitude 6.7 or greater since 2005. 1939.


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