With micro-earthquakes it is now possible to study medicane, Mediterranean hurricanes – Corriere.it

News on the front of study and monitoring of tropical cyclones in the Mediterranean come from an innovative international research. The research focused on monitoring cyclones with sophisticated high-tech instruments linked to seismological techniques, applied for the first time in the Mediterranean. Medicane (MEDIterranean hurriCANE) are comparable to tropical cyclones that develop in the Mediterranean area capable of raising violent wave motions. The pressure generated by sea waves capable of producing a signal picked up by seismic stations, from which scientists can extract useful information both for studying and for monitoring these extreme weather-marine phenomena.

I study

what emerges from the results of the study, published on Scientific Reports
conducted by researchers from the Department of Biological, Geological and Environmental Sciences of the University of Catania, the Etna Observatory of the National Institute of Geophysics and Volcanology (Ingv), the Department of Geoscience of the University of Malta, the Royal Observatory of Belgium , of the National Center for the environmental characterization and protection of the coastal strip, marine climatology and operational oceanography of Ispra and of the AC2 company.

The medicane Apollo

Between the end of October and the beginning of November 2021, eastern Sicily (in particular the provinces of Catania, Messina and Syracuse) was hit by heavy rains, gusts of wind and storm surges due to the presence of a medicane in the Ionian Sea, referred to as Apollo. A medicane is a low pressure system that can be defined as a small-scale tropical cyclone with heavy rains, winds and storm surges, but with a duration limited to a few days due to the reduced extension of the Mediterranean. The strong winds generated by the phenomenon cause an intensification of wave motion, with waves that can reach and exceed 3.5 meters in height.

Microseisms

The waves of the sea, through the impact on the coast or with the pressure fluctuations that propagate from the surface to the seabed, transfer energy to the mainland which is recorded by the seismographs as a signal characterized by very low amplitudes. Up until a few years ago, these micro-earthquakes were classified as background noise and discarded. In this work the signals recorded by 78 seismic stations installed in coastal areas in Italy, Malta and Greece, the data of significant height of the sea waves acquired from buoys and also the data on the state of the sea from test maps have been analyzed and integrated. of numerical models, explains Andrea Cannata, professor at the University of Catania.

Data and analytics

The period from October 20 to November 5, 2021 was considered to include the initial formation of Apollo, its peak (October 28-29) in terms of wind speed, rainfall intensity and wave height, and subsequent loss of intensity . During the days of progressive intensification of Apollo continues Cannata, the seismic stations installed in the Ionian area showed a gradual increase in the energy content of the microseisms in a particular frequency band (0.1-0.2 hertz). was thus identified and reconstructed there seismic signature of the medicane. Using two different tracking methods based on seismic signals, it was possible to follow Apollo’s movement during the days when it reached its maximum intensities, adds the professor. The position obtained from our seismic analyzes coincided with the real position of the medicane obtained from satellite images. The work conducted by the scholars therefore proposes a innovative approach for the study and monitoring of extreme marine weather events in the Mediterranean through the use of microseisms. This research paves the way for the development of a sea state monitoring system that integrates data acquired from different instruments such as wave buoys, geostationary satellites, high frequency HF radars and seismometers, the scientists explain.