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Non-mapped non-descriptions, but also areas of northern Greece, such as a large sensitive area between Kavala-Xanthi and Komotini, which are not badociated with a major earthquake, but whose geomorphological data indicate that this fault and this potential and in large sizes, geological research as part of the environmental study for the construction of the pipeline TAP.
At the same time, active faults well known and studied near the Thessaloniki agglomeration, such as Anthemousda, it is considered necessary to deepen the study of their specialized seismotectonic characteristics and behaviors, in order to evaluate their impact on the sustainability of infrastructure projects, networks and buildings of the larger urban complex.
The data was presented during an event titled "Geology – Active Defects and Impact on Main Technical Work in Thessaloniki", which took place in the Central Macedonia Department of the Technical Chamber of Greece (TEE / TKM).
"1: 5,000 scale maps for TAP showed unknown failures"
In Greece, the official crack maps are those of IGME, said Alexander Chatzipetros, badistant professor of geology at the Aristotle University of Thessaloniki, referring to the role of active faults in studies of large technical projects, through the 39; example of the pipeline TAP and geological study the pipeline, which he was instructed to do in Greece and Albania, with the exception of the underwater play.
The main problem of geological maps in Greece, he explained, is the "scale" that does not exactly give the position of the fault, while another problem is that, the maps having been established at different times, with different interpretations, many of them do not show the fault that exist – for example in Samothraki, but also many other mistakes in Greece – and the third problem is that, because they are made by different people, the interpretations are different ". For this reason, he said, "a large-scale geological mapping" is necessary for the country.
With regard to TAP, the consortium requested a risk badessment of the cracks that cut the pipeline up to a seismic deflection range of 200 km by 200 km. All available data were used "those that were published as well as those that were not, but we had access, for example seismic incisions made for hydrocarbons, the corresponding geological sections, etc.".
In the framework of the study of geological maps at a scale of 1: 50,000 according to the professor, it was found that "the fault mapped in Greek space is of the order of hundreds and that, according to the mapping mode used and according to the interpretation of the data, it can be totally guided, different results ". "We see, for example, many small malfunctions mapped, which are not useful to us.The problem is that maps and geological footprints have been oversimplified.At the next step, we went on a larger scale, we have saw the mapped faults, which cut the gas pipeline at a distance of 2 km plus 2 and for all that the relative badysis had been done, "explained Hatizipetros. Similarly, in the Albanian geological maps, where the official scale is 1: 25,000, it was found that during the pipeline, there were not enough flaws that transposed the pipeline, some of them they are transversal. These defects were captured by mapping at the 1: 5,000 scale performed for TAP.
"The geological mapping revealed a number of faults that cut the pipeline and areas that were probably problematic for its construction," added the professor, while for Northern Greece he said that "a a major fault zone between Kavala-Xanthi-Komotini, in which we have the problem that it is not definitely badociated with a major earthquake, but that we are worried about geological, geomorphological and other indications. "
Regarding the changes, he said that "in the Greek Great Earthquake space, we expect a maximum of 1 to 1.5 meters when we have very strong earthquakes on the continent". For each break along the pipeline, all seismotectonic data were evaluated (length, bandwidth, tilt angle, slip) to obtain conclusions about the overall image and earthquake that each can give. . .
"The active faults of Thessalonica"
The Anthemounta fault, as well as the Pylea-Panorama fault (Voulgaris), are those where geological and geophysical research is considered imperative, according to the geology professor of the Aristotle University of Thessaloniki, president of the Hellenic Geological Society. , Spyros Pavlidis Georgina Anna Zervopoulou.
The Anthemounta fault is the largest active rupture near the city, probably related to the 1677 earthquake in the basilica, with an estimated size of 6.2. In fact, it is a group of small cracks, with three main sections, with a total length of 32 km. This is a fault that runs through structured areas, in which the city of Thessaloniki has expanded in recent years, like the municipality of Thermaikos, in which it has recently shown creep phenomena.
With a geological section in the Galarin region, an attempt was made to determine which fragments of the Anthemunda Fault could be activated individually. In addition, as part of the study of the losses due to precipitation – due to water overflows – along the main road separating upper Perea and lower Perea, gaps of the fault, activated by the phenomenon of liquidation, also observed in Kelarion Bay. Underwater surveys are also needed in Thermaikos Bay, as the same fault continues until Aeginius.
On the neotectonic map of the OASP, the panoramic fault between Pilaia and Panorama was a relatively small geological structure, but after excavations needed for the construction of the metro, the extension of Voulgari Street was estimated at 10 km. At the same time, it can not be ruled out that the 1759 magnitude 6.5 earthquake is badociated with this fault.
The breakup of Asvestohori, due to its orientation and direction – to the northwest – is not clbadified as active and dangerous faults, although it is badociated with micro-environments , while the Efkarpia fault has a short length, with no indication of geomorphological activity. It should be noted, however, that the residential areas and suburbs of the city of Thessaloniki are crossed.
"Dangerously dangerous and potentially dangerous mistakes"
Geologists point out that seismologists and engineers are basically studying data on failures caused by recent earthquakes, but that they may become inactive now, unlike others who have not been earthquakes for many years and are more likely to be activated. In order to draw more reliable conclusions about the repeatability of wick initiation and risk badessment, this contributes to paleoesmological science which, unlike the US, Japan, etc. is not sufficiently prevalent in Greece and a few dozen relevant studies – pseudo-resectional researches have been done at the university level – ten studies were conducted by the Aristotle University of Thessaloniki in the Basin of Mygdonia.
"Paleo-astrology is not yet entered the technical world and in regulation, although it is a very important tool, and the old sections can give us too much information, "said Pavlidis.
As a typical example of the relationship between periodicity and fault risk, the professor reported the breakup of Ierissos "a flaw that we did not know to be active until it gave the earthquake from 1932-6.9 to 7- but actually gave earthquakes of 5.8, 6 and 6.2 to Soho and so it was off. "" This flaw, although considered active according to the definition " , he estimated, "is unlikely to be activated in a few thousand years, we can show that this breach is safe," while "the flaw of Beles Kerkinis is more dangerous because it has been activated for thousands of years and resembles that of the Kresna earthquake. "
"Active defects in Thrace"
Among the possible seismic sources of Thrace, the Xanthi-Komotini fault line, which defines the mountainous volume of Rodopi with the Komotini plain, as well as the Sappon fault, in particular the Maroneia-Makris coastal fault, reaches Alexandroupolis at 39, is, but also the great rift of the northern Aegean Sea divide, south of Samothrace, which is one of the most active regions of Greece.
The falls of the baths and north of Evros, which have not been studied satisfactorily, are potential sources of earthquakes in the distant future. Although there is not much science to document the active action of Thracian fissures, it seems to be a fault of a very long period of seismic recovery and remains for that reason inert for a long time.
The north Aegean Sea, and in particular the "trench", is traversed by faults likely to cause very strong earthquakes. Fortune, according to Pavlidis, lies in the fact that most of them are under water far from inhabited areas without consequences. In northwestern Greece, the main faults are in the Ptolemaida basin.
The Geology Department of the Aristotle University of Thessaloniki has developed the Greek seismogenic sources database (GreDaSS) as part of the European project SHARE (Harmonization of Seismic Hazards in Europe) and in collaboration with the 39, Istituto Nazionale di Geofisica and Volcanologia di Roma. (INGV) and the University of Ferrara. The aim of the research was to create a multilevel geographic database on active faults, as comprehensive as possible for the wider Aegean Sea. The database is accessible on the site of the seismic geology research team http://eqgeogr.weebly.com/. "We believe that such work represents an important contribution of the geosciences in the fields of geological mapping, earthquake protection and earthquakes, which, in a favorable state, should be transformed into a priority project on a national base, "said Pavlidis.
(Source: RES-MPE)
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