This event started a new chain reaction along the Sürgü fault, which grew into a magnitude 7.6 earthquake.
Both of these earthquakes were larger than any previously recorded for the East Anatolian Fault, even with historical records going back one thousand years.
This is not an unusual situation: Faults are unpredictable and slow. It is not uncommon for there to be gaps of hundreds or even thousands of years between the largest magnitude earthquakes on faults everywhere in the world. Previous known earthquakes in this region have reached estimated magnitudes of 7.0-7.4, for instance in 1893, 1872, 1822, and 1626.
Because the earthquake ruptures were all quite shallow, ground shaking was very intense in the surrounding areas.
The devastation is shocking. These earthquakes occurred during the coldest part of the year, in the early morning hours. Millions of people were asleep, dressed for the comfort of their beds.
When the shaking hit, those who were able to flee their homes found themselves unprepared for the biting cold and snow. Others, trapped in collapsed buildings, were similarly exposed to the elements, with an even shorter window for survival than normal. Snow and freezing conditions have hampered rescue efforts. People have been driven back into damaged buildings by the cold, increasing the hazard posed by aftershocks.
The area impacted by one large earthquake is huge; two earthquakes double the problem. The combination of a large damage zone with widespread disruption of roads by faulting and landslides makes it very hard to bring in aid. Experience shows that many areas may not receive outside aid for some time. Again, the bad weather compounds this problem.
It is important to note that although the earthquakes themselves were natural, the devastation is in part man-made. Horrific footage of collapsing buildings illustrates the risk of inadequate construction in an earthquake-prone region. Globally, multi-story concrete slab buildings with incorrect concrete or insufficient reinforcement have proved to be extremely dangerous.
Although modern building codes do exist in Türkiye, many of the structures predate their existence. Retrofitting existing buildings is expensive and difficult, but without such work, many millions of people will remain at risk. Further, there is evidence that many newer buildings did not conform to the code;
some of these buildings collapsed on Monday. Enforcing existing seismic building codes and addressing the hazard posed by older buildings will be critical going forward. These earthquakes show how construction amnesties may seem practical in the short term but are dangerous in that they delay the only real solution to earthquake hazard.
This unfolding tragedy is a stark reminder of the seismic hazard that exists in many parts of Türkiye and the surrounding regions. It is easy to forget, during the long, quiet periods between shaking, that the Earth could move at any time. Even now, southern Türkiye continues to experience sporadic aftershocks.
There is a hazard of further earthquakes both in the impacted region and on the faults bordering it, many of which have been stressed by these crustal shifts. Earthquake triggering has already been seen in this event, but can potentially occur over a much longer time interval.
Such a series of events was observed in northern Türkiye on the North Anatolian Fault. Starting in 1939, stress triggering led to a series of ten additional major earthquakes, culminating in the magnitude 7.6 Izmit earthquake in 1999.
Earthquakes are inevitable, but the damage and deaths they produce can be minimized. The first priority right now must be to provide aid to those impacted by Monday's deadly events.
However, the second must be to look beyond, to what can be done before the next tremor-which could hit in a hundred years, or tomorrow.
* This article has been penned by Dr Judith Hubbard -- a visiting assistant professor at the Department of Earth and Atmospheric Sciences at Cornell University -- for Türkiye's state-run news agency.
