Note4Students

From UPSC perspective, the following things are important :

Prelims level: Earthquakes, Tectonic Plates

Mains level: Read the attached story

turkey

More than 4000 people died and several hundred were injured after a major earthquake of magnitude 7.8 hit south-central Turkey and Northwest Syria.

What is an Earthquake?

An earthquake is an intense shaking of the ground caused by movement under the earth’s surface.
It happens when two blocks of the earth suddenly slip past one another.
This releases stored-up ‘elastic strain’ energy in the form of seismic waves, which spreads through the earth and cause the shaking of the ground.

What exactly causes Earthquakes?

As we know, the earth’s outermost surface, crust, is fragmented into tectonic plates.
The edges of the plates are called plate boundaries, which are made up of faults.
The tectonic plates constantly move at a slow pace, sliding past one another and bumping into each other.
As the edges of the plates are quite rough, they get stuck with one another while the rest of the plate keeps moving.
Earthquake occurs when the plate has moved far enough and the edges unstick on one of the faults.
The location below the earth’s surface where the earthquake starts is called the hypocenter, and the location directly above it on the surface of the earth is called the epicentre.

Turkey and Syria lie in a seismically active region
The region where the earthquake has struck lies along a well-known seismic fault line called the Anatolia tectonic block that runs through northern, central, and eastern Turkey.
It is a seismically active zone — though not as active as, say, the Himalayan region which is one of the most dangerous regions in the world from the perspective of earthquakes.

Turkey is frequently shaken by earthquakes. In 2020 itself, it recorded almost 33,000 earthquakes in the region.
Turkey is located on the Anatolian tectonic plate, which is wedged between the Eurasian and African plates.
On the north side, the minor Arabian plate further restricts movement.
One fault line — the North Anatolian fault (NAF) line, the meeting point of the Eurasian and Anatolian tectonic plates — is known to be “particularly devastating”.
Then there is the East Anatolian fault line, the tectonic boundary between the Anatolian Plate and the northward-moving Arabian Plate.
It runs 650 kilometers from eastern Turkey and into the Mediterranean.
In addition to this, the Aegean Sea Plate, located in the eastern Mediterranean Sea under southern Greece and western Turkey, is also a source of seismic activity in the region.

Where was the earthquake epicentered?

The centre of the earthquake was centred about 33 km from Gaziantep, around 18 km deep.
Its effect was felt across West Asia, Northern Africa and South Eastern Europe with residents of Lebanon, Cyprus, Greece, Israel and Egypt also reporting tremors.

Aftermath: Many Aftershocks hits the region

Aftershocks are a sequence of earthquakes that happen after a larger mainshock on a fault.
Aftershocks occur near the fault zone where the mainshock rupture occurred and are part of the “readjustment process” after the main slip on the fault.
While they become less frequent with time, although they can continue for days, weeks, months, or even years for a very large mainshock.

An accurate prediction of an earthquake requires some sort of a precursory signal from within the earth that indicates a big quake is on the way.
Moreover, the signal must occur only before large earthquakes so that it doesn’t indicate every small movement within the earth’s surface.
Currently, there is no equipment to find such precursors, even if they exist.

India is among the 45 countries, which have so far offered assistance to Turkey.
It’s sending search and rescue teams of the National Disaster Relief Force (NDRF) and medical teams along with relief material to the West Asian nation.