Why turkey earthquake more dangerous

Subject: Geography

Section: Physical geography ( Geomorphology)

Context:

Two large earthquakes, one of magnitude 7.8 and closely followed by a magnitude 7.5, hit south-eastern Turkey, claiming at least 17,000 lives and counting, wreaking considerable damage in Turkey as well as Syria. Nearly 200 aftershocks have followed with earthquakes of magnitude 6 being reported in the region three days after the first tremblor.

What causes earthquakes?

The earth’s crust is made up of roughly 15 massive segmented chunky slabs called tectonic plates which are constantly in motion.
The land on which buildings are built rests on these plates.
The plates continually collide, push and grate against each other and the meeting points of these plates are made up of a series of ‘faults.’
The pent-up energy from the moving plates, along faultlines, is often released when an imbalance in pressure causes rocks on either side of the fault to re-adjust.
- One set of rocks rising up relative to the other is a ‘normal’ fault, and one sliding down relative to the other is a ‘reverse’
- When they grate or move past one another, it’s a ‘strike-slip.’
- The energy released travels as waves that cause the ground to shake.

What kind of earthquake occurred in Turkey and Syria?

Turkey and Syria lie at the confluence of three plates — the Arabian Plate, the Anatolian Plate and the Eurasian Plate, making the region an extremely seismically active zone.
The Arabian Plate is inching north into Europe, causing the Anatolian Plate (which Turkey sits on) to be pushed out west.
The bulk of Turkey sits on the Anatolian Plate between two major faults: the North Anatolian Fault and the East Anatolian Fault.
Geologists say that the earthquakes were from a ‘strike-slip’ which is typical of the earthquakes in the region.

Why were these earthquakes so devastating and deadly?

A lack of enforcement of building codes in Turkey and the timing of the earthquake in the early morning are believed to be major factors for the death and devastation inflicted.
The region hosts many fault systems, so the region is highly prone to earthquakes.
- At magnitude 7.8, the February 6 event is much bigger than the ones the area has experienced before. The fault system runs along nearly 190 km which is why the impact of the earthquakes was so far-ranging.
- The second earthquake, of 5 magnitude, occurred further to the north on a different but adjacent fault system called the Sürgü Fault.
The aftershocks can be experienced as far away as Cairo (950km) and Istanbul (815km).

Measurement of earthquakes:

The earthquake events are measured either according to the magnitude or intensity of the shock.
- The magnitude scale is known as the Richter scale. The magnitude relates to the energy released during the quake. The magnitude is expressed in absolute numbers ranging between 0 and 10.
- The intensity scale is named after Mercalli, an Italian seismologist. The intensity scale takes into account the visible damage caused by the event. The range of intensity scale is between 1 and 12.