An unprecedented series of earthquakes has been registered during the past 6 days in the area between the islands of Thira (Santorini) and Amorgos. As recorded by the University of Athens Seismological Laboratory, by Wednesday afternoon (5th February) there had been a total of 419 tremors during this period with a magnitude of 3.0 or over on the Richter scale. Of these 71 were of magnitude 4.0 or over, and 379 at a focal depth of 10 km or less, making them more noticeable on the ground. There had been a small increase in the average magnitude over the 5-day period, with the strongest, at 5.0 Richter, registered just after 3.00 pm on Tuesday, 28.2 km south-west from Amorgos at a depth of 12.8 km.

While the experts have stated that the tremors are due to activity on a fault line and not from any of the area’s active volcanoes, there is fear that a major earthquake is yet to come, and tourists, foreign workers and residents have been leaving Santorini by ship and by air, with the ferry companies and airlines laying on extra services to cope with the demand. Emergency services units have also been arriving on the island with a tracker dog, drone operators and airborne rescue specialists. Schools have been closed, and some residents have been sleeping in their cars for safety.

On Monday there was a joint emergency session of the two government committees devoted to seismic monitoring and risk assessment, held at the ministry for Climate Crisis and Civil Protection and chaired by the President of the Earthquake Planning and Protection Organisation, Professor Efthymios Lekkas. Among those present were the minister for Climate Crisis and Civil Protection Vasilis Kikilias, the deputy minister Evangelos Tournas, General Secretary for Civil Protection Vasilis Papageorgiou and representatives of the Fire Service management.

After a thorough review of developments to date, the committee members issued the following joint statement.

1. Seismic activity within the caldera [of Santorini] remains at a low level.
2. The sequence of seismic activity has continued to be elevated over the past 48 hours with more than 200 tremors in the area of Anydros, between Thira and Amorgos (quakes with a maximum magnitude of 4.5).
3. The ongoing seismic activity around the island of Anydros is due to undersea fissures running in a NE-SW direction and is not related to volcanic activity.
4. The Committees propose the following preventive measures:
a. Schools should remain closed on Monday 03/02/2025 in Thira, Anafi, Ios and Amorgos.
b. Citizens should:
– avoid large gatherings inside buildings;
– avoid approaching abandoned buildings;
– avoid approaching and remaining in the harbours of Ammoudi, Armeni, Korfo and the Old Harbour of Thira;
– remove non-structural hazards in their buildings and drain water from swimming pools;
– choose safe routes while moving about within the urban fabric and on the provincial road network, especially at points where there are pronounced slopes and landslides may ensue;
– immediately leave shore areas in the case of a strong seismic tremor.
The committees will meet again at midday tomorrow. For more information on antiseismic protection, citizens are referred to the websites of the Earthquake Planning and Protection Organisation (oasp.gr) and the ministry for Climate Crisis and Civil Protection (civilprotection.gov.gr).

Following a further meeting of the emergency committees on Wednesday it was decided that schools on the four islands would remain closed until Friday, a measure also adopted by 9 other Cycladic islands including, Syros, Naxos, Paros and Antiparos.

Following the 5.0 magnitude tremor on Tuesday afternoon, Prof. Lekkas was asked whether the latest tremor could be the main one, but said that it was too early to tell. Ideally I would like to see a tremor of 5.2 to 5.4 he said, which would probably signal the climax, but it is impossible to say how long the sequence will continue, it could take days, weeks or even months, as in the case of Arkalohori in Heraklion. In an earlier interview he had stated that there was little likelihood of a tremor of over 6.0 Richter, as the magnitude is determined by the length of the fault involved, which in this case is small. To date there seems to have been little damage, apart from rockslides.

According to the BBC, quoting “officials”, more than 11,000 people had left Santorini by Wednesday afternoon, with around 7,000 departing by ferry and 4,000 people leaving by air. However, others are remaining, stating that they have taken adequate precautions and are confident that they would not come to harm. Both Aegean Air and Sky Express have been laying on extra flights, and following the school closures Sky Express announced that it was making free tickets available from Wednesday 5th to Sunday 9th February for school children up to the age of 12 who wished to fly to Athens, as well as school teachers employed on the islands of Santorini, Ios, Amorgos and Anafi.

As of Wednesday afternoon, the situation remained the same, with quakes continuing to occur with the same frequency and intensity. The only change to the situation was that gradually worsening weather, with high winds in the Aegean, was hampering the efforts of those who still wished to leave by ferry.

Generally the situation on the island remains calm, with little sign of panic. The anxiety of those who have chosen to leave the island is understandable, with the ground moving under people’s feet every half an hour or so in some cases – one resident told ERT News that she was leaving because “We just want to get some sleep”. However, the long period of lesser shocks has given both residents and the authorities time to prepare for a possible large earthquake, which has not always been the case in the past. Moreover the involvement of the emergency committees at an early stage and the reassuring statements of Professor Lekkas have contributed to the impression of a situation which is to some extent under control. But as the Professor has made clear, seismologists can only make their best predictions based on previous data, and there is no way of knowing what the final outcome may be.

Latest developments
Professor Lekkas’s desire to see a climactic earthquake may have been fulfilled on Wednesday night, when a tremor of 5.1 Richter according to the University of Athens Seismological Laboratory – 5.2 according to some initial assessments – struck 30.4 km NE of Santorini at a depth of 7 km. This was followed by a flurry of 15 tremors of 4.0 magnitude and above up to 8.00 am on Thursday morning. Interviewed on Mega TV’s early morning news programme, Professor Lekkas said that this was a good sign, since as long as the sequence of lesser tremors went on there was less likelihood of a major one of 6.0 Richter or above. The continuing tremors signalled a dissipation of energy he said, and while the possibility of 6.0 magnitude earthquake could not be altogether ruled out, the probability was being progressively reduced.

(Haniotika Nea, iefimerida.gr, civilprotection.gov.gr)