What Causes Earthquakes in Turkey? A Look at the Complex Tectonic Forces

Turkey is situated in one of the most seismically active regions on Earth. The country has long faced the threat of devastating earthquakes due to its location at the intersection of three major tectonic plates – the Eurasian Arabian and Anatolian plates. Recent powerful earthquakes that caused mass destruction and tragic loss of lives in Turkey once again highlights the vulnerable position of the country. But what exactly causes Turkey’s susceptibility to frequent and damaging quakes? Let’s take a closer look at the tectonic forces at play.

Turkey’s Restless Geological Location

Turkey straddles several major fault lines between interacting tectonic plates. The northern part of the country sits on the Eurasian plate. To the south, the Arabian plate slides northward towards the Eurasian plate. Sandwiched between these two plates is the Anatolian plate – a smaller tectonic plate comprising most of Turkey. This complex boundary region is riddled with active fault lines that frequently generate earthquakes.

The biggest threat comes from the collision zone between the Arabia and Anatolian plates, known as the East Anatolian Fault. This 1000 km long strike-slip fault runs along southeast Turkey into northern Syria. As the Arabian plate moves north, it grinds against the Anatolian plate causing the buildup of stresses that are eventually released as earthquakes.

Several other active faults also crisscross Turkey adding to its vulnerability. These include the North Anatolian Fault running along northern Turkey and the Aegean region. Western Turkey is influenced by the extensional tectonics between the Anatolian plate and the Aegean Sea plate.

A History of Destructive Earthquakes

Turkey’s hazardous location at the boundary of converging tectonic plates has resulted in some of the most damaging earthquakes in history. Over 100,000 lives have been lost in Turkey due to earthquakes in the last century alone.

The devastating 1939 Erzincan earthquake with a magnitude of 7.8 took around 33,000 lives. The 1999 Izmit earthquake registering 7.6 killed over 17,000 people. Most recently, the 2011 Van earthquake in eastern Turkey claimed over 600 lives.

But perhaps the most infamous is the 7.4 magnitude 1999 İzmit earthquake that led to nearly 18,000 fatalities and caused immense damage across the industrial heartland of the country. It highlights Turkey’s vulnerability arising from poor construction standards that amplify earthquake losses.

Underground Forces Triggering Earthquakes

Let’s look at the processes going on deep below the surface that ultimately cause the ground to shake in Turkey.

Plate Motion and Strain Accumulation

The Arabian plate is slowly but steadily pushing north against the Anatolian plate at a pace of about 2 cm per year. However, the collision is not smooth. Friction between the plates prevents them from sliding past each other easily. This causes strain to build up in the crust over decades and centuries.

Rocks deform elastically to accommodate the plate motion. When shear stress exceeds the strength of rocks along a fault, the built-up strain is released abruptly in the form of an earthquake. The two flanks of the fault suddenly jerk sideways, sending out seismic waves that make the ground shake at the surface.

Fault Slippage

Most major earthquakes in Turkey originate along strike-slip faults like the East Anatolian and North Anatolian faults. As the name suggests, slabs of crust on either side of such faults predominantly move horizontally past each other to relieve pent-up tectonic pressures.

During an earthquake, one side of the fault rapidly slides a few meters to over 10 meters relative to the other side. This displacement of the Earth’s surface manifests as the ground shaking that can last from a few seconds to over a minute. Afterslip along the fault can continue for hours and even months after the mainshock.

Liquefaction

Apart from directly damaging buildings and infrastructure, earthquakes in Turkey also amplify their effects through soil liquefaction. Loose granular soil saturated with water can temporarily behave like a liquid when shaken rigorously during an earthquake. This causes the soil to lose strength and collapse structures sitting above it.

Liquefaction occurred during the 1999 Kocaeli earthquake, causing damage to port and storage facilities near the fault zone. The possibility of liquefaction highlights the need for earthquake-resilient building designs in Turkey's quake-prone regions.

Monitoring Earthquakes and Minimizing Damage

Advanced seismic networks run by Turkey’s Disaster and Emergency Management Presidency provide round-the-clock monitoring of earthquake activity across the country. Seismic data enables quick characterization of fault slip, shake intensity patterns, and potential damage in the aftermath of a major quake.

These insights help guide emergency response and identify vulnerable areas for strengthening building codes and retrofitting older structures. Stringent building standards have been successful in minimizing earthquake losses in California. Similar measures for constructing quake-resilient buildings and infrastructure must be implemented across Turkey’s earthquake zones.

Public education programs are also essential for better earthquake preparedness and survival skills during a big quake. With its dangerous tectonic location, Turkey will continue facing earthquake risks. But through science-guided mitigation efforts, their disastrous impacts can be reduced and managed effectively.