The violent wave motions generated by Medicanes and common storms generate seismic signals useful for the study and monitoring of extreme meteorological-marine phenomena.
Study meteorological-marine phenomena with seismology tools in order to obtain a better understanding of extreme events also resulting from climate change.
This is the objective of the Long-term analysis of microseism during extreme weather events research: Medicanes and common storms in the Mediterranean Sea, just published in the prestigious journal 'Science of the Total Environment'.
The study was conducted by a multidisciplinary research team from the Department of Biological, Geological and Environmental Sciences of the University of Catania (Alfio Marco Borzì, Andrea Cannata and Carmelo Monaco), the Etna Observatory of the National Institute of Geophysics and Volcanology (Flavio Cannavò and Vittorio Minio), of the Royal Observatory of Belgium (Raphael De Plaen and Thomas Lecocq), of the Department of Engineering of the University of Palermo (Giuseppe Ciraolo), of the Department of Geoscience of the University of Malta (Sebastiano D'Amico), of the National Center for Environmental Characterization and Protection of the Coastal Zone, Marine Climatology and Operational Oceanography of ISPRA (Carlo Lo Re and Marco Picone) and of the Department of Earth and Geoenvironmental Sciences of the University of Bari (Giovanni Scardino and Giovanni Scicchitano).
The Medicane (from MEDIterranean hurriCANE, i.e. Mediterranean hurricane) is a low pressure system identifiable as a small-scale tropical cyclone. It shares some characteristics with the latter, including heavy rains, winds and storm surges, but its duration and intensity are limited due to the reduced extension of the Mediterranean Sea. Despite this, it is capable of producing extensive damage along the exposed coasts, constituting a high risk factor due to the high population density and production infrastructure present.
The "common seasonal storms" are, however, the classic seasonal disturbances such as, for example, the Atlantic disturbances capable of producing rain, intense winds and consequently storm surges. The strong winds generated during these latest meteorological events cause an intensification of the wave motion with waves that can even exceed 3,5 meters in height.
"Between November 2011 and February 2023 at least 9 Medicanes and several common seasonal storms affected the Mediterranean Sea and the coastal areas of the various countries bordering it” explains Vittorio Minio.
Sea waves are capable of transferring solid energy to the Earth in the form of weak seismic waves, which are recorded by common seismic stations.
“The seismic signals produced by the impact of waves on the coast or by pressure fluctuations are known as 'microseism' and constitute an omnipresent signal on Earth, characterized by extremely low amplitudes”, adds Andrea Cannata “Through the analysis and integration of signals recorded by 104 stations installed in Italian, Maltese, Greek and French coastal areas, sea wave height data acquired from wave buoys and data on the state of the sea from hindcast maps (obtained from numerical modeling and validated by observations) it was highlighted how microseism contains valuable information for monitoring the temporal and spatial development of extreme meteorological-marine phenomena. In fact, during the days of progressive intensification of the analyzed events, the seismic stations installed in the areas affected by the meteorological phenomena showed a gradual increase in the energy content of the seismic waves. Furthermore, using two different localization methods based on seismic signals, it was possible to locate and follow the Medicanes in their movement".
The analyzes conducted made it possible to obtain the "seismic signature" and the "seismic magnitude" of Medicanes and common seasonal storms.
"Medicanes show a frequency content ranging from 0.18 Hz to 0.35 Hz, while common storms are characterized by higher frequencies (0.3 Hz to 0.7 Hz).” continues Alfio Marco Borzì “Even the different values of "seismic magnitude", which vary according to the spatial extension of the sea affected by waves with heights greater than three metres, obtained for the two types of meteorological phenomena, allow the distinction.
Since seismometers were among the first geophysical instruments to be installed and since we are now able to seismically distinguish Medicanes and common storms, the study of microseism could help reconstruct any changes in the intensity and/or frequency of these phenomena, caused by global warming”, concludes Borzì.
The work was financed by the ARCHIMEDE project (Prin 2022 PNRR call), by the i-waveNET project (Interreg Italia-Malta, notice 2/2019, priority axis 3) and by the PON project “Research and Innovation 2014-2020 Action IV.5 - Doctorates on green topics”.
Full citation of the publication: Borzì, Alfio Marco, et al. "Long-term analysis of microseism during extreme weather events: Medicanes and common storms in the Mediterranean Sea." Science of The Total Environment (2024): 169989.
Link to the study:
Satellite images of the Medicanes that affected the Mediterranean Sea from 2011 to 2023 (©NasaWorldview). The red star shows the position of the microseism source obtained from the analyzes conducted.