Date: 08/02/2023

Relevance: GS-1: Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc., geographical features and their location-changes in critical geographical features (including water-bodies and ice-caps) and in flora and fauna and the effects of such changes.

Key Phrases: Earthquakes, Magnitude, Turkey, Aftershocks, International Aid, Tectonic Plates, Faults, Fractures, Devastation, Fault Line, Tectonic Boundary.

Context:

• Three earthquakes with magnitudes of 7.8, 7.6, and 6.0 on the Richter scale have caused widespread devastation in Turkey and Syria, and their tremors were felt as far away as Cyprus (456 km), Lebanon (874 km), Israel (1,381 km), and Egypt (1,411 km).

Key Highlights:

• At least 40 aftershocks followed the first quake, with some of magnitude as high as 6.7. Two more earthquakes of 7.6 and 6.0 magnitude struck the region nine hours later.
• This 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 in first two days.
• More than 2,000 people are feared injured, and several remain trapped under rubble. Turkey has announced a Level 4 alert calling for international aid; U.S., European Union, Russia, India and Azerbaijan have reportedly dispatched aid.

What Makes Turkey A Hotbed Of Seismic Activity?

• Turkey is frequently shaken by earthquakes. In 2020 itself, it 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. The Earth’s outermost layer comprises of 15 major slabs, called tectonic plates.
  • The boundaries between these plates are a system of faults and fractures between two blocks of rocks. Any sudden movement along these faults can cause earthquakes.
• 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”.
  • The NAF, one of the best-understood fault systems in the world, stretches from the south of Istanbul to northeastern Turkey, and has caused catastrophic earthquakes in the past.
  • In 1999 itself it caused two earthquakes of 7.4 and 7.0 magnitude each in Gölcük and Düzce provinces. Almost 18,000 people died and more than 45,000 were injured.
• 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.
• According to an estimate, almost 95% of the country’s land mass is prone to earthquakes, while about a third of the country is at high risk, including the areas around the major cities of Istanbul and Izmir and the region of East Anatolia.

Why Do Shallow Earthquakes Cause So Much More Damage?

• These earthquakes emerged from relatively shallow depths which made them devastating. Shallow earthquakes are generally more devastating because they carry greater energy when they emerge on the surface.
  • The first earthquake, of magnitude 7.8, originated 17.9 km below the Earth’s surface.
  • All the subsequent ones, including the one of 7.5 magnitude, emerged from even closer to the surface.
• Deeper earthquakes lose much of their energy by the time they come to the surface. The deeper quakes spread farther though the seismic waves move conically upwards to the surface even as they lose energy while travelling greater distances, and hence cause less damage.
• The earthquake in Nepal some time ago, whose tremors were felt in many parts of northern India.
  • It originated about 25 km below the Earth’s surface and did not cause large scale damage.
  • But the Nepal earthquake also had a low magnitude of 5.8 magnitude is the other indicator of how destructive an earthquake will be.

Magnitude of the Earthquake:

• Magnitude is a measure of how big the waves are, while the strength refers to the energy it carries.
• Magnitude is measured on a logarithmic scale, which means the seismic waves produced by a magnitude 6 earthquake have 10 times higher amplitude than the ones produced by a magnitude 5 earthquake.
• The energy differential is even higher, 32 times for every change of 1 in magnitude.
  • This means that the 7.8 magnitude earthquake in Turkey produced 100 times bigger waves than the 5.8 earthquake in Nepal, and 1,024 (32 x 32) times more powerful.
  • In general, every change of 0.1 in magnitude results in about 1.4 times changes in energy.

Conclusion:

• Between 2013 and 2022 there were 30,673 reported earthquakes across the world. Only two of them reached the same magnitude as this earthquake.
• In 2021, in a “catastrophic projection”, an expert panel warned that 2, 00,000 buildings in Istanbul stand at risk to medium- or high-level damage, jeopardizing the lives of three million residents in the city.
• Multiple studies, including one from 2020, have reiterated the caution, averring that multiple districts are vulnerable to earthquakes of more than 7.4 magnitude. It’s not a question of “if” but “when”, experts opine.
• Reports indicate that the situation in Syria is becoming increasingly dire due to the aftermath of earthquakes and the challenges posed by harsh winter storms.
  • Both government and opposition-controlled areas are being affected, with limited access to vital resources such as water, healthcare, and food.
  • The Syrian Civil Defence, operating in opposition-held areas, has declared a state of emergency and appealed to the international community for assistance in rescuing civilians.

Source: The Hindu

Mains Question:

Q. Why is Turkey prone to devastating earthquakes and what makes the recent earthquake a catastrophic one in particular? Discuss (250 words).