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Deep Faults and Tectonic Sismogenic Knots in Albanides

Afat SERJANI, ProGEO-Albania, Sherbimi Gjeologjik Shqiptar, Tirana, Albania
E-mail: [email protected]
Abstract. It is impossible to predict the future earthquake activity, but with detailed geological-sismogenic studies, we can determine the areas of the most probability for the coming next earthquakes. In geological Map of Albania it is clearly seen block, geological construction of tectonic zones. There are formed plates of different sizes. In Ionian and Korabi tectonic zones there is noted the correlation the evaporite rocks with epicenters of earthquakes. It is discovered strong relation of the earthquakes with deep faults and tectonic knots. Just to this subject in case of different tectonic zones in Albania, it is concentrated this paper. Deep tectonic faults and tectonic knots in external and internal tectonic zones and in Albanian Alps and Cukali subzone there are evidenced and put in geological schemes, which are put at the end of the text..

1. Introduction.
We know where earthquakes happened in the past and hence where they may happen again if we determine in details, deep, tectonic faults, which generate earthquakes. There is opinion that Albanian territory, concerning the earthquake frequency is after Japan (Morelli C. 1969). According Sulstarova E., (1987), in Albania, since the 177 year before new era up to 1963, there are evidenced more than 200 macrosismic, earthquake shakes and eight of them were catastrophic for Durresi city. The earthquake of 26 November 2019 by a strong of 6.3 magnitudes caused extensive damages in Durresi and Tirana regions, terrified population and waked up seismologists and geologist. We can’t forgive, that such terrible earthquakes, in Albania are registered last century, in Dibra (1967), and in Shkodra (1979). It is discovered the strong relation of the earthquakes with deep faults and tectonic knots. That is why we decided to concentrate this subject to deep sizmogenic faults in different tectonic zones of our country.
Commonly, sismologists and geologists have argued that main factor of earthquakes in Albania is the collision of the African Plate (Adria micro plate) with Eurasian Plate, through Ionian zone, so called orogen (Sulstarova, Aliaj 1990, Aliaj 2020). Distribution of the earthquake’s epicenters shows that all earthquakes, which have happened since the ancient times are next or near with this contact in territory of Albania, up to Shkodra City, and with the Hellenic Trench south, in Greece (Papazahos et alt. 1993). It is clearly seen that seismicity decreased going from west to east. Ormeni Rr. (2006) has précised seismogenic zones with the representative epicenters: one meridional zone from Palasa to Shkodra and second, oblique from Vlora to Dibra.
A lot of earthquakes in territory of Albania are linked with deep faults distributed mainly in external tectonic zones. Never must forget the territories where have not been earthquakes up to know.
In geological Map of Albania (2004) there is clearly seen that all territory is divided in tectonic plates of different sizes. For simplification, we have done separate sheets of distribution of deep faults in External zones (Ionian, Kruja and Krasta, Fig.1), in inner tectonic zones (Mirdita and Korabi Fig. 2.), and in Albanian Alps and Cukali plates (Fig. 3.).
In Geological Map of Albania there are clearly noted some regularities concerning the deep faults such as: Deep faults of thrust character have smoothly angles up to medium angles; overthrusts from east to west have medium angles, and the angle of deeping it is going to grow from south to the north. In North of Albania there are seen deep faults of western depth. Confines of tectonic zones and subzones are separated by deep thrust faults, in all cases.
Thrust tectonic system in Albania, was discovered for the first time by S. Zuber (Papa A, 2001) and was supported later by Albanian geologists who were worked in prospection of oil and gas and mineral resources in Albania.
It is important to remember that shakes by earthquake are depending by geological formation where happened earthquake. The highest damages are caused in strong rocks such as magmatic and metamorphic rocks, in limestone and dolomite, while in flysch formation and in molasses, the earthquake shakes and strikes commonly, extinguishes gradually.
In western part, including Alps, there were shallow epicenters of earthquakes, in earth core, and not in mantel. Koçiaj S., (1989) has concluded that in eastern Albania the sizes and depth of blocks are biggest than in western part. It is supposed that core it is going to be thinner towards the west.

2. Deep faults and tectonic knets in external zones
In external tectonic zones there is evidenced the concordance between tectonic and sismogenic faults, conformed by solution of the earthquake’s focal mechanism (Sulstarova E., 1987). The main deep faults in Ionian zone have commonly, thrust character. Kruja zone is thrusted on Ionian zone and Krasta zone is thrusted on Kruja, while Mirdita zone it is thrusted on Krasta subzone south and on Cukali subzone north. Commonly, eastern anticline belts or chains in Ionian zone, there are thrusted on syncline belts, west.
Below there are presented deep faults and tectonic knots in Ionian zone from west to east:
1. Palasa-Dukat-Vlore-Seman. In Llogara, this deep fault coincides with the contact of Adria micro plate. This deep fault goes north to Patos-Verbas anticline (Velaj T., 1991), and further North West of Dumrea. 2. Deep fault in western flank of Fterra anticline chain. It comes from Sajadha (Greece) to Livadhja-Nivice Bubar-Fterra-Bolena-Matogjini, further north is covered by molasses formations of PAD. 3. Central Kurveleshi deep fault, which came from Greece to Bistrica-Zhulati-Gusmar phosphorite deposit to Vermik-Matogjini knot. It is everywhere accompanied by gypsum. In this deep fault there are outcropped volcanic and metamorphic rocks, in Picari, Zhulati, Gusmari and Vermiku (Serjani A., Bajo I., 1992). 4. Deep fault of over thrusted of Bureto- Çajupi-Berati anticline belt on the Lunxheri-Memaliaj-Gllava-Mbreshtan syncline belt up to Dumrea salt diapir. 5. Two parallel faults in Permeti syncline belt from Çarshova south to west of Çorovoda, to east of Poliçani, and going north up to Cerriku. The continuation north of these faults it is covered by molasses formation of Neogene of Tirana Basin. 6. The cover thrust of Kruja zone on Ionian zone, from Leskoviku south to Elbasani-Krraba-Priska-Borizan-Mamuras-Milot-Shengjin-Velipoje. 7. Thrust fault of Krasta zone overthrusted on Kruja zone. 8. Deep fault of Mirdita ophiolite zone on Krasta zone, in southern part and on Cukali subzone on north-eastern part, up to Fierza…
In Ionian zone there are formed some large tectonic knots, just in the places where deep faults there are crossed by transversal ones. They represent the areas of the most probability and danger for causing earthquakes. They are as following:
1. Palasa-Dukati tectonic knot. 2. Mursi-Çifliku. 3. Krongj-Bistrica-Delvina. 4. Zhulat-Kardhiq-Picar. 5. Luzat-Benca. 6. Bashaj-Matogjini. 7 Dumrea wide knot. 8. Leskoviku tectonic knot, where are closed Kruja, Krasta and Mirdita tectonic zones. 9. Elbasani tectonic knot, where is crossed Vlora-Dumre-Diber sismogenic fault with longitudinal faults. 10. Shkodra tectonic knot.
Mursia, Bistrica, Matogjini and Dumrea tectonic knots there are in salt rocks, forming salt diapirs.
Salt diapirs in Albania outcrop in Ionian and Korabi zones. They have get up to the surface through deep paleofaults mainly in places of the tectonic knots (Serjani & Qillo, 1998). The largest outcrops of salt rocks, there are related to the Vlora-Elbasan-Diber-Shkup (Scopie) regional sismogenic fault. Here is placed Dumrea salt diapir of about 220 km2; Mali Bardhe and Bellova large evaporate domes in Peshkopi region and Dibra outcrops in Northern Macedonia. These lasts there are placed just at knot of crossing: Vlora-Elbasan-Dibra-Shkup transverse sismogenic fault with Prespa-Ohrid-Dibra longitudinal fault. Usually, evaporites have acted as a detachment layer for thrusts, but have also been cut by thrusts which bring them to the surface (Velaj, at alt. 1999).
There is defined the connection of the deep faults and salt rocks with epicenters of earthquakes, there is conformity. The correlation of the deep faults with salt rocks is verified by geological data and by solution of the focal mechanism of earthquakes (Sulstarova, E., 1987, Muço B., 1994)

3. Tectonic faults and tectonic knots in inner tectonic zones.
Geological surveys in sc. 1: 50 000 and 1: 10 000 have found and mapped many faults, which can generate earthquakes. But in inner zones there are found many cover faults, which in some places are near to the surface. Ormeni Rr., and Marku S., (2009) have argued in case of Gjirica earthquake that it was a shallow earthquake linked with normal fault, placed inside the Vlore-Elbasan-Diber sismtectonic oblique belt, crossed with Korça-Dibra longitudinal fault. In Peshkopi Depression have been strong earthquakes during August 1942, November 1967, June 1978, and August 1978. In all cases earthquakes are accompanied by long after shakes. In Korabi zone, there are some intercalations of local faults, crossing faults, forming small blocks, which generate local earthquakes. In inner zones there the following deep faults:
1. The most long thrust fault is the contact of Mirdita zone, from Leskoviku south, up Shkodra and further north-east along with the contact of Cukali subzone and further along with western contact of Tropoja ultrabasic massive to Kosovo. 2. The second, longitudinal thrust fault it is that which accompanied the thrust contact of Korabi zone on Mirdita ophiolite, from east of Biza south to Ternova, west of Gurre Lura, to Bicaj and Shtigjen. 3. In northern part, there is a parallel thrust fault, in some places in fragmental form, of old Korabi formations with Mirdita ophiolites of Bulqiza ultrabasic massifs. Because of tectonic events in some places tectonic contacts are covered.
4. Inside of Mirdita zone, there are mapped some oblique faults such as: 4. Bushal fault, in ophiolite rocks, which goes from Qelaj west, up to Fushe-Arres, where is met with the fault coming from south, from Rubiku and turned in Dimal-Fushe Arrez, going northeast to Qafa e Malit-Shire-Kalimash-Kukes-Gjegjan-underneath the Koritnik Mountain. 5. Another longitudinal fault is that from Bardhaj to the north to Lushaj-Bardhaj-Kurbnesh, while to the north goes according the contact of Triassic/Cretaceous deposits, and with ultra basic rocks of Kuksi massif to Gjegjani tectonic knot.
6. in this map there is deep fault between Mirdita zone and Dry Mountain (Pogradeci-Korça region), representing carbonate frame of ophiolites 7. In mollase formation, of Korça inner depression there is mapped one meridional deep fault from Kloça south to Pogradeci north.
In Korça-Erseka region, there are mapped some geological, block faults such as: Qafa-Qarri-Kozeli-Q.Kazanit-Mollas, which generate local, shallow, and may be dangerous earthquakes. Some cover tectonic blocks there are mapped in the Kamenica pass region, in border, in Shales, Borova and Gostivishti region, north. Thrust tectonic here it is developed in carbonate formation of J3-Cr1 and in flysch formations of Pg.
The main tectonic knots in inner zones there are: 1. Fierza knot; 2.Bardhoc Gjegjan; 3.Fushe-Arrez; 4.Zerqan-Valikardh; 5. Bize-Zdrajc; which is located just in sismogenic, oblique fault Vlore-Dumre-Elbasan-Diber fault. 6. Topojan tectonic knot; 7. Helmes-Shtike tectonic knot; 8. Lekoviku knot is included in external zones. 9. Kurbneshi tectonic knot. 10. Shkodra knot.
It was difficult to examinate and to do the correlation of tectonic faults in inner tectonic zones, because they are distributed without any regularity, with different direction, and different sizes.

4. Deep faults and tectonic knots in Albanian Alps and in Cukali subzone.
There is clearly seen the plate geological construction of this area. Shkodra territory it is may be the most dangerous sismogenic knot in Albania. Some deep faults begun just from Shkodra tectonic knot and continue to the north and north east directions. The main deep faults in Albanian Alps zone and in Cukali subzone there are as following:
1. The first deep fault it is the fault of Mirdita zone on Cukali subzone. It seems as it comes from Shkodra knot, but in dead it comes from south. It is the thrust fault of Mirdita zone on Krasta subzone and in Shkodra region it turns his direction from northwest to north east. The author has the opinion that this deep, thrust fault it is the fault of Mirdita tectonic zone on Krasta subzone in south-east and on Cukali subzone north-east up to Fierza. 2. Deep fault which divided Kelmendi Subzone from Valbona subzone, it goes from Shkodra south to Gruemira, toward the north to Maja e Madhe in Radomira, Peja Pass and continues north to state confine. 3. The next deep fault of thrust character it is thrust tectonic of Cukali zone on Albanian Alps zone, which goes to north east up to Selimaj, where joined with thrust fault of Mirdita zone on Cukali subzone and goes further north of Mirdita zone on Albanian Alps zone. 4. At the most north part of Albanian territory it is separated by tectonic fault Vermoshi region from Kelmendi highland. 5. Gashi zone it is overthrusted on Albanian Alps zone.
In Albanian Alps territory there are some oblique faults, which can generate earthquakes as well. They are as following: 6.Oblique fault from Koshtica mountain (1762m) towards north-east up to Gropat e Selces, where turns to southwest up to west of Vukli and again turns direction towards the northeast up to Qafa e Panikut, and again to the south direction up to the end of Lepusha Valley and to Vejusha Mountain. We have the opinion that this fault of cover character in carbonate formation, is a shallow fault…
In Albanian Alps zone, there are mapped a lot of local longitudinal and oblique’s tectonic faults. Less is seen such faults in Cukali subzone. In Kelmendi subzone predominates longitudinal faults south-north, while in Valbona subzone predominate oblique faults west-east direction.
In Albanian Alps and Cukali subzone we have noted the following tectonic knots: 1. Fierza tectonic knot. 2. Tectonic knot between mountains of Trashani and Mardam in west and Zorzit Mountain in east. This knot can be named Nderhysaj tectonic knot. 3. Curraj I Eperm tectonic knot. 4. Barxolle-Oxbibaj tectonic knot. 10. Shkodra knot.

5. Conclusions
In Ionian zone there are widespread longitudinal tectonic faults, while in the inner tectonic zones there is not discovered any regularities.
In Albanian territory there are a lot of sismogenic deep fault and tectonic knots, which can generate earthquakes.
There is determined the concordance of deep faults and tectonic knots with salt rocks and with epicenters of the earthquakes.
The more dangerous areas, where can be earthquakes we consider:
1. The area of western deep faults next to seaside and next to the contact between African (Adria) Plate with orogen or Eurasian plate from Ionian Rivera south up to Shkodra tectonic knot. 2. The second more dangerous area, it is sismogenic, oblique belt with evaporates: Vlora-Elbasan-Diber.

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