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Devastating Earthquake in Turkey - UPSC Key Points

Feb 8, 2023

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Context

Probable Question

Highlights of the recent Earthquakes

About Earthquake

Causes of Earthquakes

Prediction of earthquakes

The scales of measurement for magnitude

Measuring the intensity

Why Turkey is a hotbed of seismic activity

The Earthquake Risk in India

Frequently Asked Questions

Our today's edition of Current Affairs is here. Read to know more about- Devastating Earthquake in Turkey. Also, find the topic's relevance to the UPSC CSE syllabus below:

For Prelims: Physical Geography

Hypocenter, Epicenter, Aftershocks, North Anatolian fault (NAF) line, East Anatolian fault line

For Mains: GS Paper I (Important Geophysical phenomena)

About Earthquake, Causes of Earthquakes, Prediction of earthquakes, The scales of measurement for magnitude, Measuring the intensity, About Aftershocks, The Earthquake Risk in India.

Context

Three earthquakes (measuring 7.8, 7.6, and 6.0 magnitude on the Richter scale) have devastated Turkey and Syria, while impacting neighboring regions such as Cyprus (456 km away), Lebanon (874 km), Israel (1,381 km), and Egypt (1,411 km).

Probable Question

What causes an earthquake and why can’t it be predicted with precise accuracy? (150 words, 10 marks)

Highlights of the recent Earthquakes

Earthquake with a magnitude of 7.8 is the strongest earthquake to shake the region in more than 100 years and has killed at least 3,800 people across Turkey and Syria.
The historic 2,200-year-old stone castle, which was used as an observation point during Roman times has been damaged.
One of the most prominent sites in Maltaya, the famous Yeni Mosque which dates back to the 13th century, had collapsed.
The quake’s focus was 18 km deep, according to the U.S. Geological Survey. The epicentre was about 33 km from Gaziantep.

About Earthquake

An earthquake is a severe shaking of the ground brought on by underground movement.
According to the United States Geological Survey (USGS), it occurs when two earthen blocks unexpectedly slide past one another.
This causes seismic waves, which propagate through the earth and cause the ground to tremble, to be released as "elastic strain" energy.

NOTE:

United States Geological Survey (USGS):

USGS was created by an act of Congress in 1879.
The U.S. Geological Survey has evolved over the decades, matching its talent and knowledge to the progress of science and technology.
USGS provides science about the natural hazards that threaten lives and livelihoods, the water, energy, minerals, and other natural resources we rely on, the health of our ecosystems and environment, and the impacts of climate and land-use change.
USGS scientists develop new methods and tools to enable timely, relevant, and useful information about the Earth and its processes.

Causes of Earthquakes

The earth’s outermost surface, crust, is fragmented into tectonic plates.
Tectonic plates are 15 major slabs that the Earth’s outermost layer comprises.
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. However, due to their rough edges, they get stuck with each other, while the rest keeps moving.

Earthquake occurs when the plate has moved far enough and the edges unstick on one of the faults.
According to the British Archaeological Survey, any sudden movement along these faults (rough edges of the plates) can cause earthquakes.
USGS says that “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 epicenter.”

Prediction of earthquakes

A precursory signal from deep within the ground that warns of a major quake is necessary for an accurate earthquake forecast.
In order to prevent the signal from indicating every tiny movement beneath the earth's surface, it must only occur before significant earthquakes.
Even if they do exist, there is currently no equipment to find such precursors.

The scales of measurement for magnitude

Today, there are many measures of an earthquake’s magnitude, with the most famous (and outdated according to USGS) being the Richter Scale.
The Richter Scale (denoted as ML) is a logarithmic scale that was devised in 1935 by Charles Francis Richter.
In the Richter Scale each step represents a tenfold increase in magnitude i.e. if an earthquake measures 7 on the Richter Scale, it will have 10 times the magnitude of one measured 6.
The method developed by Richter was strictly valid only for certain frequencies, and distance ranges. Consequently, the Moment Magnitude Scale (denoted as Mw) was developed.
In Mw a physical quantity proportional to the slip on the fault multiplied by the area of the fault surface that slips. This is related to the total energy released in the earthquake.
This scale provides a more accurate estimate of magnitude, especially as one goes higher up the scale. Like the Richter Scale, this too is a logarithmic scale.

Measuring the intensity

An earthquake causes many different intensities of shaking, depending on how deep it is located on the earth’s crust and how far it is from its epicenter.
Earthquakes of lower magnitude can be more intense if they are located in the more shallow ground or if the area where they occur has more loose soil, etc.
Intensity scales, like the Modified Mercalli Scale and the Rossi-Forel scale, measure the amount of shaking at a particular location.
The Modified Mercalli Scale is the most commonly used intensity scale, ranking earthquake intensity on a scale of I. (not felt) to XII. (extreme). For example, the recent earthquake that Turkey experienced observed IX. or violent intensity.

Why Turkey is a hotbed of seismic activity

Turkey is frequently shaken by earthquakes.
In 2020, Turkey recorded almost 33,000 earthquakes in the region, according to Disaster and Emergency Management Authority (AFAD). Out of these, 332 earthquakes were of magnitudes 4.0 and higher.
Turkey’s proneness to earthquakes comes from its tectonic location. According to one estimate, almost 95% of the country’s land mass is prone to earthquakes, while about a third of the country is at high risk.
This is because Turkey is located on the Anatolian tectonic plate, which is wedged between the Eurasian and African plates.
The North Anatolian fault (NAF) line, the meeting point of Eurasian and Anatolian tectonic plates is known to be “particularly devastating”, which has caused catastrophic earthquakes in the past.
The East Anatolian fault line, the tectonic boundary between the Anatolian Plate and the northward-moving Arabian Plate, is also a source of seismic activity in the region.

The Earthquake Risk in India

India's increasing population and extensive unscientific construction mushrooming all over, including multistoried luxury apartments, huge factory buildings, gigantic malls, supermarkets as well as warehouses and masonry buildings keep India at high risk.
In the last 15 years, India has experienced 10 major earthquakes that have resulted in over 20,000 deaths.
As per the current seismic zone map of the country, over 59% of India’s land area is under threat of moderate to severe seismic hazard-; that means it is prone to shaking of MSK Intensity VII and above (BMTPC, 2006).
In fact, the entire Himalayan belt is considered prone to great earthquakes of magnitude exceeding 8.0 and in about 50 years, four such earthquakes have already occurred as 1897 Shillong (M8.7); 1905 Kangra (M8.0); 1934 Bihar-Nepal (M8.3); and 1950 Assam-Tibet (M8.6).
Scientific publications have warned of the likelihood of the occurrence of very severe earthquakes in the Himalayan region, which could adversely affect the lives of several million people in India.

Additional Information:

About Aftershocks:

It is the after-effect of a larger mainshock earthquake on a fault. It is a sequence of earthquakes.
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, they can continue for days, weeks, months, or even years for a very large mainshock.
They can also cause significant damage.

List of some of the world’s deadliest earthquakes in India and its neighboring countries:

June 22, 2022: In Afghanistan, more than 1,100 people die in a magnitude 6.1 earthquake.
April 25, 2015: In Nepal, more than 8,800 people are killed by a magnitude 7.8 earthquake.
August 3, 2014: A magnitude 6.2 earthquake near Wenping, China, kills more than 700 people.
September 24, 2013: A magnitude 7.7 quake strikes southwest Pakistan, killing more than 800 people.
March 11, 2011: A magnitude 9.0 quake off the northeast coast of Japan triggers a tsunami, killing more than 20,000 people.
October 8, 2005: A magnitude 7.6 earthquake kills over 80,000 people in Pakistan occupied Kashmir (POK) region.
January 26, 2001: A magnitude 7.7 quake strikes Gujarat in India, killing 20,000 people.

National Center for Seismology (NCS)

It is the nodal agency of the Government of India for monitoring earthquake activity in the country.
NCS maintains a National Seismological Network of more than 150 stations each having state of the art equipment and spreading all across the country.
NCS monitors earthquake activity all across the country through its 24x7.

News Source: The Indian Express, The Hindu

https://indianexpress.com/article/explained/explained-sci-tech/turkeys-earthquake-what-causes-an-earthquake-and-why-cant-it-be-predicted-8427452/

https://www.thehindu.com/sci-tech/energy-and-environment/explained-why-turkey-is-prone-to-devastating-earthquakes/article66476957.ece

Frequently Asked Questions

Why Turkey is Prone to Earthquakes?

Turkey’s proneness to earthquakes comes from its tectonic location. According to one estimate, almost 95% of the country’s land mass is prone to earthquakes, while about a third of the country is at high risk.

Why Turkey is facing a series of natural disasters?

Turkey is frequently shaken by earthquakes. In 2020, Turkey recorded almost 33,000 earthquakes in the region, according to Disaster and Emergency Management Authority (AFAD). Out of these, 332 earthquakes were of magnitudes 4.0 and higher. Turkey’s proneness to earthquakes comes from its tectonic location. According to one estimate, almost 95% of the country’s land mass is prone to earthquakes, while about a third of the country is at high risk. This is because Turkey is located on the Anatolian tectonic plate, which is wedged between the Eurasian and African plates.

What causes Earthquakes?

The earth’s outermost surface, crust, is fragmented into tectonic plates. Tectonic plates are 15 major slabs that the Earth’s outermost layer comprises. 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. However, due to their rough edges, they get stuck with each other, while the rest keeps moving. Earthquake occurs when the plate has moved far enough and the edges unstick on one of the faults. According to the British Archaeological Survey, any sudden movement along these faults (rough edges of the plates) can cause earthquakes. USGS says that “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 epicenter.”

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