Turkey earthquake: What is a ‘strike-slip’ quake? Why was it so severe?

An extremely powerful 7.8 magnitude earthquake caused widespread devastation in Turkey and neighbouring Syria. It was followed by two more massive earthquakes of 7.5 and 6.0 magnitude hit the country within 24 hours. Over 2,300 people are confirmed to have died. It is feared that the death toll could rise significantly in the coming days. 

The earthquake’s epicentre was in southern Turkey near Syria’s northern border and at a depth of 18 kilometres. The area felt several aftershocks. 13 significant aftershocks (magnitude of at least 5) were felt in the first 11 hours after the first quake. 

What type of earthquake struck Turkey? Why was it so devastating?

The earthquake was a strike-slip quake. This is an earthquake caused by a strike-slip fault. It is caused when two tectonic plates slide past one another horizontally instead of vertically. Tectonic plates are the parts that make up earth’s crust, massive solid rock plates nestled together. In generally accepted scientific theory, these plates have been moving for the last 3.4 billion years.

When two such tectonic plates happen to go sliding past each other sideways instead of up and down, it is called a strike-slip quake. In a strike-slip earthquake, as the plates push against each other on a vertical fault line, stress builds up until one of the plates slips horizontally. This releases a tremendous amount of strain which can result in an earthquake.

One of the most famous strike-slip faults is the San Andreas Fault in California in the US. Scientists had warned that a catastrophic quake is long overdue in the region. It has been a part of several films too.

In the case of the turkey quake, one block moved east while the other went west. As they ground past each other as one slip, it caused an extremely powerful and devastating earthquake.

The region where the earthquake occurred is a seismically active area known. This region is known as the East Anatolian fault zone. It has seen many devastating earthquakes in the past. Turkey had a major earthquake as recently as January 2020. A 6.7 magnitude caused significant damage.

The latest earthquake was one of the biggest strike-slip earthquakes to hit on land, Alex Hatem, a USGS research geologist noted. Moreover, it was near populated areas which led to increased damage. Several buildings collapsed in cities like Diyarbakir in Turkey and Aleppo in Syria.

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