Earthquake off Rhodes
On Tuesday morning at 2:17 am, residents of Crete were awakened by the second earthquake warning in less than 2 weeks, this time coming from Google’s Android Earthquake Alerts, the 112 SMS warning system apparently not having been activated.

Predicted by the warning as being of 6.6. magnitude, it was eventually classified by the Seismological Laboratory of the University of Athens as a 6.00 magnitude tremor, situated 23.6 km north of Rhodes, at a focal depth of 80 km. While it rattled buildings and caused some alarm among the residents of Rhodes, it caused only superficial damage on the island.

According to sources quoted in Iefimerida.gr, the tremor was particularly strong and lasted a long time. The Fire Service was examining buildings on the island for damage but so far nothing serious had been found and there were no injuries. The residents of Rhodes traditionally hang decorated plates from the walls of their houses, and these seem to have been the main casualties of the tremor. Otherwise, there was no panic, and the residents reacted to the earthquake with sang froid, the paper said.

The earthquake was felt strongly in the Turkish province of Mugla on the Aegean coast, and at the resort of Marmaris, about equidistant with Rhodes from the tremor’s epicentre, there was considerable panic. According to Ekathimerini, the governor of Marmaris Idris Akbiyik said in a post on X that 69 people had been injured after jumping from windows and balconies during the tremor, while a 14-year-old girl was hospitalised with a panic attack, and died shortly afterwards.

In view of the depth at which the tremor occurred, it was not considered a particularly dangerous one. Speaking to ERT not long after the tremor, Professor Efthymios Lekkas, head of the Earthquake Planning and Protection Organisation struck a reassuring tone: “It’s an earthquake whose main characteristic is its depth,” he said. “Its depth is 60 km [sic], which means that even though it was felt over a wide area of the Dodecanese and Turkey, it will not have had significant effects on the surface; there will be no tsunami, and most significantly there will be no major aftershocks.” He added that it was most probably the main earthquake, because of its depth. “The phenomenon was very pronounced for the inhabitants of Rhodes, but beyond that we will not see anything special,” he said.

Earthquake off Crete
Some 12 hours later, a second earthquake struck off the south-east of Crete, with a magnitude of 5.2 and a focal depth of 8 km. The location was 82.6 km south-east of Heraklion, in the sea 14 km east of Chrisi Island, which lies close to the town of Ierapetra. Despite its being much shallower, the impact was still very limited. Although shaking was felt over a large part of Crete, damage seems to have been limited to some rockfalls and landslides on the Ierapetra-Myrtos-Viannos road, which were quickly repaired by municipal crews. Local schools were closed for the rest of the day as a precaution.

As with the earthquake off Rhodes the experts were quick to dismiss the possibility of any complications from the tremor, but said that there was no connection between the two earthquakes. In a post on Facebook, Akis Tselentis, Professor of Seismology at the National and Kapodistrian University of Athens said:

“The latest earthquake of 5.3 [sic] at Chrisi is in an area where there have been many relatively small tremors over the past 4 years. Since I holiday just opposite, I had observed them. They are due to [movement of] the upper part of the undersea plate. I believe it was the main quake. The well-known seismic fault has exhausted its force but some aftershocks are expected. People bathing on the beaches should take care. Get small children and vulnerable people away from the water, in case of a small-scale tsunami.”

Earthquakes in Turkey
Lying across several fault lines, Turkey is highly prone to earthquakes, which tend to have more devastating effects, especially when they occur in urban areas. If the inhabitants of Marmaris reacted with less sang froid than those of Rhodes it may be because they had in recent memory the tremors in South Eastern Turkey and Syria in February 2023, which, of around 7.8 magnitude, constituted the deadliest disaster in Turkey’s modern history.

According to Wikipedia, there was widespread damage in an area of about 350,000 sq km, about the size of Germany. An estimated 14 million people, or 16 percent of Turkey’s population, were affected. The confirmed death toll in Turkey was 53,537, while estimates of the number of dead in Syria were between 5,951 and 8,476. What was striking was that large numbers of modern buildings which should have withstood the tremors were destroyed, a fact put down to lax enforcement of anti-seismic building codes by the government.

The risks for Istanbul
The Rhodes tremor has focussed attention anew on the possibility of a major earthquake in Istanbul. The city lies in the 1,200 km long North Anatolian Fault Zone and scientists have predicted a 64 per cent chance of a tremor of 7.0 or higher magnitude before 2030, caused by the breaking of the NAFZ under the Sea of Marmara.

With a population of over 15 million, the city is home to 18 per cent of the Turkish population, and a 7.0+ magnitude earthquake will inevitably have a devastating effect. Only a month ago an earthquake of 6.2 magnitude struck with an epicentre in the Sea of Marmara and caused widespread damage to buildings in and around the city, but only one fatality. (It should be remembered that the Richter scale, still used in the media as a shorthand for the more sophisticated scales now employed by scientists, is logarithmic, so that each unit of increase in magnitude represents an approximate 32-fold increase in the amount of seismic energy released.)

In the city, there is a sense of the inevitability of a major seismic event, with local inhabitants as well as local authorities hurrying to do what they can to reinforce the buildings under their control. While efforts to protect buildings have intensified since 2023, the task of bringing a city with thousands of old buildings, and many more constructed in ignorance or defiance of antiseismic codes, up to modern standards of earthquake protection, is enormous.