An unexplained earthquake continues in Santorini, Greece, increasing residents' anxiety. Authorities have declared a state of emergency, and about three-quarters of the island's population of 15,000 has evacuated.
Santorini, well known as a honeymoon destination, and nearby islands are experiencing unprecedented seismic activity. During the past week, earthquakes have become more frequent, with a total of 6,000 recorded in the past two weeks. The Greek Ministry of Citizen Protection has declared a state of emergency for Santorini and is ramping up its response.
Santorini is a volcanic island located in a Hellenistic caldera, but there has been no major eruption since the 1950s. However, seismic activity began suddenly at the end of last month. Athanasios Ganas, a researcher at the National Observatory of Greece, analyzed that this earthquake began as a result of the Santorini volcano awakening last summer. However, this earthquake shows a different pattern from typical volcanic earthquakes. Generally, volcanic earthquakes exhibit low-frequency characteristics, but the earthquakes currently occurring do not have such characteristics.
Another issue is the uncertainty whether the current earthquakes are precursors to a major earthquake or independent phenomena. If the earthquakes up to now are precursors, there is a possibility of a larger earthquake occurring in Santorini. Joanna Frowker, a professor at the University College London Disaster Risk Reduction Institute, noted, "Some large earthquakes may be preceded by small or moderate earthquakes."
However, experts say that such rules are difficult to apply to the earthquakes occurring in Santorini. Hong Tae-kyung, a professor in the Department of Earth System Science at Yonsei University, stated, "Even in areas where earthquakes frequently occur, it is rare for them to happen continuously like this," adding, "It is very difficult to predict whether seismic activity will exceed the threshold without knowing the current state of the fault precisely."
Efforts to identify earthquake patterns using artificial intelligence (AI) technology are also underway. A joint research team from Google and Harvard University developed a predictive model that learned from data on 131,000 main earthquakes and aftershocks worldwide using AI technologies such as deep learning in 2018. The research teams from Google and Harvard have begun analyzing the Santorini area using this technology, but there have been no significant results yet. The current earthquakes are larger than those in the past, which limits the ability to find accurate patterns.
Professor Hong added, "While scholars are using AI and machine learning to learn earthquake-related information, the nature of each fault zone varies, and so do the scale and outcomes, requiring vast amounts of data," noting, "Given the current lack of sufficient data, it will take considerable time before we reach a stage where we can accurately predict earthquakes."
References
Nature (2018), DOI: https://doi.org/10.1038/s41586-018-0438-y