Timely earthquake warning systems which rely on recording the propagation of seismic waves are one of the features of the network operated by the Institute of Physics of the Earth’s Interior and Geohazards, a part of the Hellenic Mediterranean University (HMU) which is based in Chania.
Professor Filippos Vallianatos, of the University of Athens, who is the Institute’s Director and also holds the UNESCO chair on Solid Earth Physics and Geohazards Risk Reduction which is established at the Institute, has many years of experience in earthquake research. In a recent interview he told Haniotika Nea of proposals to extend the Institute’s network, with the installation of additional sensors, to areas such as the Samaria National Park.
At the Institute’s premises in Halepa data is collected from its seismological network, which numbers some 18 stations in the Southern Aegean, from Gavdos and Chania to Tinos and Santorini, and from the Southern Peloponnese and Kythera to the Dodecanese. In Crete there are seismological stations at Halepa, Rodopou, Palaiochora, Tria Monastiria outside Rethymnon, the Odigitria Monastery and Knossos in the nomos of Heraklion, and elsewhere. At the same time the Institute is developing geodetic stations for monitoring ground deformations in selected areas of Crete.
Staff of the Institute of Physics of the Earth’s Interior and Geohazards of the Hellenic Mediterranean University (HMU), which is based in Chania. From the right: Professors Filippos Vallianatos and Ioannis Makris, Assistant Professors Maria Kouli and Vasileios Saltas. Photo: Haniotika Nea.
At the Institute’s premises, the newspaper met the Director Professor Vallianatos, HMU Professor and lead researcher at the Institute Ioannis Makris, Assistant Professor and lead researcher Vasileios Saltas, and Assistant Professor and researcher Maria Kouli. Professor Vallianatos demonstrated the “nerve centre” of the seismological system, where data from a mild earthquake taking place at the time appeared shortly afterwards on the computer screens.
Referring to the recent earthquake south of Chania, he noted that “the stations of the network of the HMU’s Institute of Physics of the Earth’s Interior and Geohazards, which is part of the Hellenic Unified Seismological Network (HUSN), clearly recorded the signals from that earthquake. The first arrivals of these waves produce sufficient data to trigger the Emergency Warning Systems, which can minimise the effects of a strong seismic event. The planned extension of the network to areas such as the Samaria National Park, with the installation of new sensors, could be a help to mountaineers as well as to the residents of areas adjoining these systems ….”
According to the data received by the HMU’s network, the earthquake on 13th August was near to the surface (around 10 km deep), of 4.9 magnitude and a few kilometres south of the Samaria National Park. Mr Vallianatos noted that “this region constitutes a unique natural laboratory where geoscientists can study the orogenic processes of the formation of Alpine-type landforms resulting from the convergence of Africa and Eurasia and the disappearance of the remainder of the Tethys Ocean under the Aegean. These processes give rise to intense seismicity in the region, the best known earthquake thus produced being that of 365 AD, which released energy equivalent to a magnitude of 8.0 to 8.3 and produced a tsunami which overwhelmed the Eastern Mediterranean.” As regards the earthquake of 13th August, it was caused by “sudden compressive movements in the descent of the African lithosphere,” the Professor said.
Monitoring stations of the Seismological Network of Crete. Image: Fdsn.org/ Google Maps.
Mapping seismic accelerations in Chania
In addition, as it does after every seismic event in the area, the Institute produced a map of the distribution of strong seismic movements (peak ground acceleration or PGA) in the city of Chania, based on data from the network of PGA sensors installed in the city, which is unique in the territory of Greece. The system is a valuable resource for the development of civil protection plans. Its functioning is overseen by a post-doctoral researcher at the Institute, Giorgos Hatzopoulos.
The Institute’s activities
The HMU’s Institute of Physics of the Earth’s Interior and Geohazards is active in a broad spectrum of research being carried out in the scientific and technological fields of seismology, physics of the Earth’s interior and applied geophysics. It is engaged in close, long-term collaboration with research teams in Greece and almost all the Mediterranean countries, as well as the UK, Japan and the USA. It also collaborates with the UNESCO Disaster Risk Reduction directorate.
The Institute’s activities include:
– Research into seismic risk in urban and non-urban areas, as well as at sites of major infrastructure and technical works.
– Microzone studies in cities for the minimisation of seismic risk.
– Identification of pre-seismic signatures in areas of both weak and strong seismicity.
– Research into seismic sources and strong ground movements in relation to the planning of major works and infrastructure.
– Seismotectonic analysis for the location and monitoring of active faults, and others.
Professor Vallianatos pointed out that the Institute has been internationally recognised for its wide-ranging contributions to the understanding of seismicity.
(Haniotika Nea, 30/08/23)