M. Kouli, Sofia Peleli, V. Saltas, J. Makris, F. Vallianatos
In recent years, there is a growing interest concerning the development of a multi-parametric system for earthquakes’ short term forecast identifying those parameters whose anomalous variations can be associated to the complex process of such events. In this context, the Robust Satellite Technique (RST) has been adopted herein with the aim to detect and map thermal anomalies probably related with the strong earthquake of M6.3 occurred near the city of Larissa, Thessaly on March 3rd 2021 10:16:07 UTC. For this purpose, 10 years (2012-2021) of daily Night-time Land Surface Temperature (LST) remotely sensed data from Moderate Resolution Imaging Spectroradiometer (MODIS), were analyzed. Pixels characterized by statistically significant LST variations on a daily scale were interpreted as an indicator of variations in seismic activity. Quite intense (Signal/Noise ratio > 2.5) and rare, spatially extensive and time persistent, TIR signal transients were identified, appearing twenty five days before the Thessaly main shock (pre-seismic anomalies: February 6th, February 11th March 1st), the day of the main earthquake (co-seismic anomaly) and after the main shock (post-seismic anomalies: March 4th, 10th and 17th). The final dataset of thermal anomalies was combined with geological and structural data of the area of interest, such as active faults, composite seismogenic sources, earthquake epicenter and topography in order to perform preliminary spatial analysis.
{"title":"Robust Satellite Techniques for mapping thermal anomalies possibly related to seismic activity of March 2021, Thessaly Earthquakes.","authors":"M. Kouli, Sofia Peleli, V. Saltas, J. Makris, F. Vallianatos","doi":"10.12681/bgsg.27058","DOIUrl":"https://doi.org/10.12681/bgsg.27058","url":null,"abstract":"In recent years, there is a growing interest concerning the development of a multi-parametric system for earthquakes’ short term forecast identifying those parameters whose anomalous variations can be associated to the complex process of such events. In this context, the Robust Satellite Technique (RST) has been adopted herein with the aim to detect and map thermal anomalies probably related with the strong earthquake of M6.3 occurred near the city of Larissa, Thessaly on March 3rd 2021 10:16:07 UTC. For this purpose, 10 years (2012-2021) of daily Night-time Land Surface Temperature (LST) remotely sensed data from Moderate Resolution Imaging Spectroradiometer (MODIS), were analyzed. Pixels characterized by statistically significant LST variations on a daily scale were interpreted as an indicator of variations in seismic activity. Quite intense (Signal/Noise ratio > 2.5) and rare, spatially extensive and time persistent, TIR signal transients were identified, appearing twenty five days before the Thessaly main shock (pre-seismic anomalies: February 6th, February 11th March 1st), the day of the main earthquake (co-seismic anomaly) and after the main shock (post-seismic anomalies: March 4th, 10th and 17th). The final dataset of thermal anomalies was combined with geological and structural data of the area of interest, such as active faults, composite seismogenic sources, earthquake epicenter and topography in order to perform preliminary spatial analysis.","PeriodicalId":9519,"journal":{"name":"Bulletin of the Geological Society of Greece","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72612323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Boronkay, G. Stoumpos, M. Benissi, Georgios Rovolis, K. Korkaris, Despina Papastamatiou, Georgios Dimitriou, Anastasia Chrysikopoulou, Ioannis Miliotis, Aristidis Giakoumis, M. Novack, P. Marinos
The ground investigations for the construction of Athens Metro –including over 60.000 m of sampling boreholes and geological mapping of the underground tunnel face–, planned and carried out under the supervision of ATTIKO METRO S.A., offer important geological data that enrich and locally modify our knowledge for the geology of Athens Metropolitan Area (AMA). On the basis of these data, this paper presents the Geological Map of AMA as well as a revised tectonostratigraphic scheme for the area and geological profiles along several sections of the Athens Metro lines. The geological map is a synthesis of the geological data obtained from the ground investigations with the already published geological maps and includes a Mesozoic rock assemblage as well as the Neogene-Quaternary Athens Basin. The following basic conclusions can be drawn from the interpretation of these data: (a) The Athens Unit, the basement of AMA, is divided into four formations (from bottom to top), the Lower Athens Schist, the Upper Athens Schist, the Athens Sandstone-Marl Series and the Crest Limestone. (b) Ultrabasic rocks (serpentinite) constitute the basement of Athens Unit. (c) Serpentinite bodies at the eastern border of Athens Basin, have undergone almost complete metasomatism to listwanite along their tectonic contacts with Alepovouni Marble on top and Kessariani Dolomite at their base. (d) The limestone outcrops at the western border of Athens Basin (e.g., Karavas hill) form tectonic windows of Pelagonian Upper Cretaceous limestone underneath the Athens Schist and not klippen of Crest Limestone on top of it. The revised geological map also includes the Attica-Evia Fault, which is the dominant structure of the broader area, locally mapped by two sampling boreholes across the planned metro line 4.
在ATTIKO Metro s.a.的监督下，雅典地铁建设的地面调查-包括超过60,000米的取样钻孔和地下隧道面的地质测绘-提供了重要的地质数据，丰富和本地修改了我们对雅典大都会区(AMA)的地质知识。在这些资料的基础上，本文提出了AMA地质图，并对该地区进行了修正的构造地层方案和雅典地铁几段沿线的地质剖面。该地质图综合了地面调查获得的地质资料和已发表的地质图，包括了中生代岩石组合和新近系-第四纪雅典盆地。根据这些资料的解释，可以得出以下基本结论:(a) AMA的基底——雅典单元由下向上分为下雅典片岩、上雅典片岩、雅典砂岩-泥灰岩系和Crest灰岩4组。(b)超基性岩石(蛇纹岩)构成雅典股的基底。(c)雅典盆地东部边界的蛇纹岩体沿构造接触向listwanite发生了几乎完全的交代作用，顶部为Alepovouni大理岩，底部为Kessariani白云岩。(d)雅典盆地西缘的灰岩露头(如Karavas山)在雅典片岩下形成了Pelagonian上白垩统灰岩的构造窗口，而在其上形成了Crest灰岩的klippen。修订后的地质图还包括Attica-Evia断层，这是更广泛地区的主要结构，通过规划中的地铁4号线的两个采样钻孔进行局部绘制。
{"title":"Geological map of Athens Metropolitan Area, Attica (Greece): A review based on Athens Metro ground investigation data","authors":"K. Boronkay, G. Stoumpos, M. Benissi, Georgios Rovolis, K. Korkaris, Despina Papastamatiou, Georgios Dimitriou, Anastasia Chrysikopoulou, Ioannis Miliotis, Aristidis Giakoumis, M. Novack, P. Marinos","doi":"10.12681/bgsg.26895","DOIUrl":"https://doi.org/10.12681/bgsg.26895","url":null,"abstract":"The ground investigations for the construction of Athens Metro –including over 60.000 m of sampling boreholes and geological mapping of the underground tunnel face–, planned and carried out under the supervision of ATTIKO METRO S.A., offer important geological data that enrich and locally modify our knowledge for the geology of Athens Metropolitan Area (AMA). On the basis of these data, this paper presents the Geological Map of AMA as well as a revised tectonostratigraphic scheme for the area and geological profiles along several sections of the Athens Metro lines. The geological map is a synthesis of the geological data obtained from the ground investigations with the already published geological maps and includes a Mesozoic rock assemblage as well as the Neogene-Quaternary Athens Basin. The following basic conclusions can be drawn from the interpretation of these data: (a) The Athens Unit, the basement of AMA, is divided into four formations (from bottom to top), the Lower Athens Schist, the Upper Athens Schist, the Athens Sandstone-Marl Series and the Crest Limestone. (b) Ultrabasic rocks (serpentinite) constitute the basement of Athens Unit. (c) Serpentinite bodies at the eastern border of Athens Basin, have undergone almost complete metasomatism to listwanite along their tectonic contacts with Alepovouni Marble on top and Kessariani Dolomite at their base. (d) The limestone outcrops at the western border of Athens Basin (e.g., Karavas hill) form tectonic windows of Pelagonian Upper Cretaceous limestone underneath the Athens Schist and not klippen of Crest Limestone on top of it. The revised geological map also includes the Attica-Evia Fault, which is the dominant structure of the broader area, locally mapped by two sampling boreholes across the planned metro line 4.","PeriodicalId":9519,"journal":{"name":"Bulletin of the Geological Society of Greece","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77134743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Karakostas, C. Papazachos, E. Papadimitriou, M. Foumelis, A. Kiratzi, C. Pikridas, A. Kostoglou, Charalambos Kkallas, N. Chatzis, S. Bitharis, A. Chatzipetros, A. Fotiou, Chrysanthi Ventouzi, E. Karagianni, P. Bonatis, C. Kourouklas, P. Paradisopoulou, E. Scordilis, Dominikos Vamvakaris, I. Grendas, D. Kementzetzidou, A. Panou, G. Karakaisis, I. Karagianni, P. Hatzidimitriou, Odysseus Galanis
On 3 March 2021, the Mw6.3 Tyrnavos earthquake shook much of the Thessalia region, leading to extensive damage in many small towns and villages in the activated area. The first main shock was followed in the next day, on 4th of March 2021, by an “equivalent” main shock with Mw6.0 in the adjacent fault segment. These are the largest earthquakes to strike the northeastern part of Thessalia since the M6.3, 1941 Larissa earthquake. The main shocks triggered extensive liquefaction mainly along the banks of the Titarisios tributary where alluvial flood deposits most probably amplified the ground motions. Our seismic monitoring efforts, with the use of recordings of the regional seismological network along with a dense local network that was installed three days after the seismic excitation initiation, led to the improved understanding the geometry and kinematics of the activated faults. The aftershocks form a north–northwest–trending, east–northeast–dipping, ~40 km long distribution, encompassing the two main ruptures along with minor activated structures, consistent with the rupture length estimated from analysis of regional waveform data and InSAR modeling. The first rupture was expanded bilaterally, the second main shock nucleated at its northern tip, where from this second rupture propagated unilaterally to the north–northwest. The focal mechanisms of the two main shocks support an almost pure normal faulting, similar to the aftershocks fault plane solution determined in this study. The strong ground motion of the March 3 main shock was computed with a stochastic simulation of finite fault model. Coseismic displacements that were detected using a dense GPS / GNSS network of five permanent stations located the Thessaly region, have shown an NNE–SSW extension as expected from the nature and location of the causative fault. Coulomb stress changes due to the coseismic slip of the first main shock, revealed that the hypocentral region of the second main shock was brought closer to failure by more than 10 bars.
{"title":"The March 2021 Tyrnavos, central Greece, doublet (Μw6.3 and Mw6.0): Aftershock relocation, faulting details, coseismic slip and deformation","authors":"V. Karakostas, C. Papazachos, E. Papadimitriou, M. Foumelis, A. Kiratzi, C. Pikridas, A. Kostoglou, Charalambos Kkallas, N. Chatzis, S. Bitharis, A. Chatzipetros, A. Fotiou, Chrysanthi Ventouzi, E. Karagianni, P. Bonatis, C. Kourouklas, P. Paradisopoulou, E. Scordilis, Dominikos Vamvakaris, I. Grendas, D. Kementzetzidou, A. Panou, G. Karakaisis, I. Karagianni, P. Hatzidimitriou, Odysseus Galanis","doi":"10.12681/bgsg.27237","DOIUrl":"https://doi.org/10.12681/bgsg.27237","url":null,"abstract":"On 3 March 2021, the Mw6.3 Tyrnavos earthquake shook much of the Thessalia region, leading to extensive damage in many small towns and villages in the activated area. The first main shock was followed in the next day, on 4th of March 2021, by an “equivalent” main shock with Mw6.0 in the adjacent fault segment. These are the largest earthquakes to strike the northeastern part of Thessalia since the M6.3, 1941 Larissa earthquake. The main shocks triggered extensive liquefaction mainly along the banks of the Titarisios tributary where alluvial flood deposits most probably amplified the ground motions. Our seismic monitoring efforts, with the use of recordings of the regional seismological network along with a dense local network that was installed three days after the seismic excitation initiation, led to the improved understanding the geometry and kinematics of the activated faults. The aftershocks form a north–northwest–trending, east–northeast–dipping, ~40 km long distribution, encompassing the two main ruptures along with minor activated structures, consistent with the rupture length estimated from analysis of regional waveform data and InSAR modeling. The first rupture was expanded bilaterally, the second main shock nucleated at its northern tip, where from this second rupture propagated unilaterally to the north–northwest. The focal mechanisms of the two main shocks support an almost pure normal faulting, similar to the aftershocks fault plane solution determined in this study. The strong ground motion of the March 3 main shock was computed with a stochastic simulation of finite fault model. Coseismic displacements that were detected using a dense GPS / GNSS network of five permanent stations located the Thessaly region, have shown an NNE–SSW extension as expected from the nature and location of the causative fault. Coulomb stress changes due to the coseismic slip of the first main shock, revealed that the hypocentral region of the second main shock was brought closer to failure by more than 10 bars.","PeriodicalId":9519,"journal":{"name":"Bulletin of the Geological Society of Greece","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84900704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The new stratigraphic data and tectonic evolution of the Late Miocene-Quaternary basins developed in Eastern Albania are presented. The reviewed stratigraphic data for deposits filling the Ohrid, Prespa and Devolli basins show that they began to form in Late Miocene. The stratigraphic evidences from eastern Albania are confronted with the stratigraphic data from the lake basins in western North Macedonia and northwestern Greece that all show the same age of infilling. The Cenozoic tectonic evolution of Eastern Albania consists of two phases of extensional deformations, the first in Middle Eocene-Late Miocene (Pannonian/Tortonian) and the second starting in Late Miocene (Pontian s. l.). The two phases are separated by a short compressive phase at the Late Miocene (end of Pannonian/Tortonian) or pre-Pontian s. l. time. In Late Miocene (Pontian) began forming the system of the Ohrid, Prespa and Devolli basins developed along the Drini fault zone. The Korca, Kolonja, Kukesi and Tropoja basins began to form since Pliocene and the Peshkopi Basin since Early Pleistocene. Finally, only the Ohrid and Prespa lakes are still active. The Late Miocene-Pleistocene basins were filled by lacustrine, lacustrine-fluvial and terrestrial sediments of the great thickness and of varied lithology: conglomerates, gravels, sandstones, sands, claystone and marls with lignite seams. Molluscs, microflora and flora, ostracods and vertebrates are found. The Lake Ohrid is a tectonically active graben formed during two main phases of deformation: (1) a trans-tensional phase which generated a pull-apart basin, and (2) an extensional phase which leads to its present geometry. All basins in Eastern Albania are situated in a basin and range-like (graben and horst) geodynamical setting. The inferred stratigraphic and tectonic evolution of Late Miocene-Quaternary basins in Eastern Albania as well as the relief formation and thermochronological data show that the Late Miocene-Quaternary period which led to the recent geological structure of Albania and its rapid relief formation, can be accepted as ‘Neotectonic period’.
介绍了阿尔巴尼亚东部晚中新世—第四纪盆地的新地层资料和构造演化。通过对Ohrid、Prespa和Devolli盆地沉积物地层资料的整理，发现它们形成于晚中新世。阿尔巴尼亚东部的地层证据与北马其顿西部和希腊西北部湖盆的地层资料进行了对比，均显示出相同的充填年代。东阿尔巴尼亚新生代构造演化包括两个阶段的伸展变形，第一个阶段始于中始新世-晚中新世(潘诺尼-托尔顿期)，第二个阶段始于晚中新世(庞tian s. l.)。这两个阶段在晚中新世(潘诺尼期/托尔顿期末期)或前潘诺尼期被一个短暂的挤压期分开。晚中新世(Pontian)开始形成Ohrid体系，沿德里尼断裂带发育Prespa和Devolli盆地。Korca、Kolonja、Kukesi和Tropoja盆地形成于上新世，Peshkopi盆地形成于早更新世。最后，只有奥赫里德湖和普雷斯帕湖仍然活跃。晚中新世—更新世盆地为湖相、湖河相和陆相沉积，厚度大，岩性多样:砾岩、砾石、砂岩、砂石、粘土岩和褐煤缝泥灰岩。发现了软体动物、微生物群和植物群、介形虫和脊椎动物。奥赫里德湖是一个构造活跃的地堑，形成于两个主要的变形阶段:(1)反拉阶段，形成了拉分盆地;(2)伸展阶段，形成了现在的几何形状。阿尔巴尼亚东部的所有盆地都位于盆地和山状(地堑和地堑)地球动力学背景中。阿尔巴尼亚东部晚中新世—第四纪盆地的地层和构造演化，以及起伏形成和热年代学资料表明，导致阿尔巴尼亚近代地质构造和快速起伏形成的晚中新世—第四纪可以被认为是“新构造时期”。
{"title":"Stratigraphy and tectonic evolution of Late Miocene - Quaternary Basins in Eastern Albania: A Review","authors":"P. Pashko, S. Aliaj","doi":"10.12681/BGSG.22064","DOIUrl":"https://doi.org/10.12681/BGSG.22064","url":null,"abstract":"The new stratigraphic data and tectonic evolution of the Late Miocene-Quaternary basins developed in Eastern Albania are presented. The reviewed stratigraphic data for deposits filling the Ohrid, Prespa and Devolli basins show that they began to form in Late Miocene. The stratigraphic evidences from eastern Albania are confronted with the stratigraphic data from the lake basins in western North Macedonia and northwestern Greece that all show the same age of infilling. The Cenozoic tectonic evolution of Eastern Albania consists of two phases of extensional deformations, the first in Middle Eocene-Late Miocene (Pannonian/Tortonian) and the second starting in Late Miocene (Pontian s. l.). The two phases are separated by a short compressive phase at the Late Miocene (end of Pannonian/Tortonian) or pre-Pontian s. l. time. In Late Miocene (Pontian) began forming the system of the Ohrid, Prespa and Devolli basins developed along the Drini fault zone. The Korca, Kolonja, Kukesi and Tropoja basins began to form since Pliocene and the Peshkopi Basin since Early Pleistocene. Finally, only the Ohrid and Prespa lakes are still active. The Late Miocene-Pleistocene basins were filled by lacustrine, lacustrine-fluvial and terrestrial sediments of the great thickness and of varied lithology: conglomerates, gravels, sandstones, sands, claystone and marls with lignite seams. Molluscs, microflora and flora, ostracods and vertebrates are found. The Lake Ohrid is a tectonically active graben formed during two main phases of deformation: (1) a trans-tensional phase which generated a pull-apart basin, and (2) an extensional phase which leads to its present geometry. All basins in Eastern Albania are situated in a basin and range-like (graben and horst) geodynamical setting. The inferred stratigraphic and tectonic evolution of Late Miocene-Quaternary basins in Eastern Albania as well as the relief formation and thermochronological data show that the Late Miocene-Quaternary period which led to the recent geological structure of Albania and its rapid relief formation, can be accepted as ‘Neotectonic period’.","PeriodicalId":9519,"journal":{"name":"Bulletin of the Geological Society of Greece","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84823544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Scudero, G. De Guidi, R. Caputo, Vincenzo Perdicaro
Databases of tectonic stress indicators are commonly based on different types of observations at different spatial and temporal scales. Each single indicator can be variously representative of the real stress field and the relative importance of all the indicators should be accounted for before any following elaboration. We propose a semi-quantitative procedure which assigns weights to each indicator on the basis of its quality and its representative volume. In this way the indicators can be reliably combined to produce, for example, stress field maps or stress trajectories. The proposed weighting criterion has been applied to a dataset of 440 crustal stress indicators specifically compiled, gathering focal mechanisms and geological data from the literature, and original data from structural features derived from devoted fieldwork, for the southern part of the Calabrian Arc (Italy). This area represents an interesting case study because of its complex geodynamic and structural arrangement. Data were ranked and the orientation of the minimum horizontal stress (S h ) has been interpolated and smoothed on a regular grid. We drew maps of the principal stress axes and inferred the stress regimes over the investigated area. Results are in agreement with independent information from the literature and display the non-uniform orientation of the tectonic stresses and the occurrence of perturbations both at regional and local scale.
{"title":"A semi-quantitative method to combine tectonic stress indicators: example from the Southern Calabrian Arc (Italy)","authors":"S. Scudero, G. De Guidi, R. Caputo, Vincenzo Perdicaro","doi":"10.12681/BGSG.23485","DOIUrl":"https://doi.org/10.12681/BGSG.23485","url":null,"abstract":"Databases of tectonic stress indicators are commonly based on different types of observations at different spatial and temporal scales. Each single indicator can be variously representative of the real stress field and the relative importance of all the indicators should be accounted for before any following elaboration. We propose a semi-quantitative procedure which assigns weights to each indicator on the basis of its quality and its representative volume. In this way the indicators can be reliably combined to produce, for example, stress field maps or stress trajectories. The proposed weighting criterion has been applied to a dataset of 440 crustal stress indicators specifically compiled, gathering focal mechanisms and geological data from the literature, and original data from structural features derived from devoted fieldwork, for the southern part of the Calabrian Arc (Italy). This area represents an interesting case study because of its complex geodynamic and structural arrangement. Data were ranked and the orientation of the minimum horizontal stress (S h ) has been interpolated and smoothed on a regular grid. We drew maps of the principal stress axes and inferred the stress regimes over the investigated area. Results are in agreement with independent information from the literature and display the non-uniform orientation of the tectonic stresses and the occurrence of perturbations both at regional and local scale.","PeriodicalId":9519,"journal":{"name":"Bulletin of the Geological Society of Greece","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91411849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Papadimitriou, V. Kapetanidis, A. Karakonstantis, I. Spingos, I. Kassaras, V. Sakkas, V. Kouskouna, A. Karatzetzou, K. Pavlou, G. Kaviris, N. Voulgaris
On 30 October 2020 11:51 UTC, a Mw=6.9 earthquake struck the offshore region north of Samos Island, Greece, in the Gulf of Ephesos/Kuşadasi, causing two fatalities and 19 minor injuries at Samos Island, as well as 115 casualties and over 1,030 injuries in Western Turkey. Preliminary results indicate that the mainshock occurred on a northdipping normal fault, with a focal mechanism of 270o/50o/-81o. The selection of the fault plane is supported by evidence of uplift at western Samos and over 10 cm of subsidence at the northernmost edge of the central part of the island. The distribution of relocated hypocenters shows clustering of events, east of the mainshock’s epicenter, where most major aftershocks have occurred. To the west, a smaller group of aftershocks is observed, separated by a spatial gap in seismicity. The latter is likely related to the region of the fault plane where most of the co-seismic slip occurred, with Coulomb stress-transfer towards the western and eastern margins of the rupture triggering aftershock activity. The apparent complexity of the mainshock’s source time function, supported by preliminary results, could indicate the rupture of more than one structures. This could explain the relatively weak magnitude of the largest aftershock (Mw=5.0). The mainshock caused damage mainly to non-engineered constructions, i.e. old residential buildings, churches and monuments in Samos Island, and minor damage to the majority of the building stock of the island built according to the National Seismic Code. On the other hand, it caused severe damage at Izmir, especially to high-rise *Correspondence to: Panayotis Papadimitriou ppapadim@geol.uoa.gr DOI number: http://dx.doi.org/10.12681/ bgsg.25359
{"title":"First Results on the Mw=6.9 Samos Earthquake of 30 October 2020","authors":"P. Papadimitriou, V. Kapetanidis, A. Karakonstantis, I. Spingos, I. Kassaras, V. Sakkas, V. Kouskouna, A. Karatzetzou, K. Pavlou, G. Kaviris, N. Voulgaris","doi":"10.12681/bgsg.25359","DOIUrl":"https://doi.org/10.12681/bgsg.25359","url":null,"abstract":"On 30 October 2020 11:51 UTC, a Mw=6.9 earthquake struck the offshore region north of Samos Island, Greece, in the Gulf of Ephesos/Kuşadasi, causing two fatalities and 19 minor injuries at Samos Island, as well as 115 casualties and over 1,030 injuries in Western Turkey. Preliminary results indicate that the mainshock occurred on a northdipping normal fault, with a focal mechanism of 270o/50o/-81o. The selection of the fault plane is supported by evidence of uplift at western Samos and over 10 cm of subsidence at the northernmost edge of the central part of the island. The distribution of relocated hypocenters shows clustering of events, east of the mainshock’s epicenter, where most major aftershocks have occurred. To the west, a smaller group of aftershocks is observed, separated by a spatial gap in seismicity. The latter is likely related to the region of the fault plane where most of the co-seismic slip occurred, with Coulomb stress-transfer towards the western and eastern margins of the rupture triggering aftershock activity. The apparent complexity of the mainshock’s source time function, supported by preliminary results, could indicate the rupture of more than one structures. This could explain the relatively weak magnitude of the largest aftershock (Mw=5.0). The mainshock caused damage mainly to non-engineered constructions, i.e. old residential buildings, churches and monuments in Samos Island, and minor damage to the majority of the building stock of the island built according to the National Seismic Code. On the other hand, it caused severe damage at Izmir, especially to high-rise *Correspondence to: Panayotis Papadimitriou ppapadim@geol.uoa.gr DOI number: http://dx.doi.org/10.12681/ bgsg.25359","PeriodicalId":9519,"journal":{"name":"Bulletin of the Geological Society of Greece","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74453435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Xhaferri, Ruben Corijn, A. Sinojmeri, R. Swennen, Ç. Durmishi
This research is focused on the determination of the heavy mineral s (HM) load of the Vjosa and Mati river delta deposits along the Albanian coastline and it is based on X-ray Diffractometry. The Albanian coastline consists of sandy beaches at the north (Adriatic coastline) and rocky escarpments at the south (Ionian coastline). Several layers of heavy mineral deposits, up to 50 cm thick, with heavy mineral fraction up to 95% and 88% of total sample for Vjosa and Mati sediments respectively, are identified. The layers enriched in heavy minerals from Vjosa delta deposits are almost black in colour, while at Mati delta these layers are dark green coloured. Separation of the heavy from the light fraction was performed, in order to compare the different fractions between the two studied delta areas. The accumulation of HM occurs mainly in the fraction of 125-250 µm in the sediments of both deltas. The HM dominate in the magnetic field of 0.4-0.8 A/m. XRD analysis results show a great variety of minerals present in the delta samples which can be attributed to the wide variety of geological zones and lithologies that are intersected by the Vjosa and Mati rivers, respectively. In the 63-425 μ m fraction rich in heavy minerals of both delta systems considerable amounts of magnetite (up to 39.4% in Vjosa samples), chromite (up to 20.2% in Vjosa samples), garnet (up to 13.6% in Vjosa samples), ilmenite (up to 8.3% in Mati samples), rutile (up to 4.7% in Mati samples), hematite (up to 2.2% in Mati samples), and zircon (up to 2.1% in Vjosa samples) are observed. Rock forming minerals such as pyroxene, amphibole, and epidote compose significant percentages of this fraction. In addition, the presence of gold grains in Vjosa delta sediments is remarkable. Both catchment areas consist to a great extent of similar formations such as the Mirdita Ophiolite Zone and the Pindos Ophiolite complex, providing thus a similar HM fingerprint at both delta areas. Minerals that occur in higher abundances reflect the extensive presence in the drained areas of related parent rocks which are rich in these minerals and which are often more vulnerable to weathering. The samples of Vjosa river delta show high percentage of carbonate constituents , which is related to the presence of carbonate rocks of the Ionian and Kruja tectonic zones within which the hydrographic network of the Vjosa River has been developed. The samples of Mati river delta show lower abundance of carbonate minerals, reflecting the limited presence of carbonate rocks at the Kruja Zone, which occur in the catchment area of the river near its mouth.
{"title":"Study of Heavy Minerals from the Vjosa and Mati river delta sediments in Albania","authors":"E. Xhaferri, Ruben Corijn, A. Sinojmeri, R. Swennen, Ç. Durmishi","doi":"10.12681/bgsg.22989","DOIUrl":"https://doi.org/10.12681/bgsg.22989","url":null,"abstract":"This research is focused on the determination of the heavy mineral s (HM) load of the Vjosa and Mati river delta deposits along the Albanian coastline and it is based on X-ray Diffractometry. The Albanian coastline consists of sandy beaches at the north (Adriatic coastline) and rocky escarpments at the south (Ionian coastline). Several layers of heavy mineral deposits, up to 50 cm thick, with heavy mineral fraction up to 95% and 88% of total sample for Vjosa and Mati sediments respectively, are identified. The layers enriched in heavy minerals from Vjosa delta deposits are almost black in colour, while at Mati delta these layers are dark green coloured. Separation of the heavy from the light fraction was performed, in order to compare the different fractions between the two studied delta areas. The accumulation of HM occurs mainly in the fraction of 125-250 µm in the sediments of both deltas. The HM dominate in the magnetic field of 0.4-0.8 A/m. XRD analysis results show a great variety of minerals present in the delta samples which can be attributed to the wide variety of geological zones and lithologies that are intersected by the Vjosa and Mati rivers, respectively. In the 63-425 μ m fraction rich in heavy minerals of both delta systems considerable amounts of magnetite (up to 39.4% in Vjosa samples), chromite (up to 20.2% in Vjosa samples), garnet (up to 13.6% in Vjosa samples), ilmenite (up to 8.3% in Mati samples), rutile (up to 4.7% in Mati samples), hematite (up to 2.2% in Mati samples), and zircon (up to 2.1% in Vjosa samples) are observed. Rock forming minerals such as pyroxene, amphibole, and epidote compose significant percentages of this fraction. In addition, the presence of gold grains in Vjosa delta sediments is remarkable. Both catchment areas consist to a great extent of similar formations such as the Mirdita Ophiolite Zone and the Pindos Ophiolite complex, providing thus a similar HM fingerprint at both delta areas. Minerals that occur in higher abundances reflect the extensive presence in the drained areas of related parent rocks which are rich in these minerals and which are often more vulnerable to weathering. The samples of Vjosa river delta show high percentage of carbonate constituents , which is related to the presence of carbonate rocks of the Ionian and Kruja tectonic zones within which the hydrographic network of the Vjosa River has been developed. The samples of Mati river delta show lower abundance of carbonate minerals, reflecting the limited presence of carbonate rocks at the Kruja Zone, which occur in the catchment area of the river near its mouth.","PeriodicalId":9519,"journal":{"name":"Bulletin of the Geological Society of Greece","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73174654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Groundwater quality is substantial for social and economic activities in Greece since the majority of the cultivated land is irrigated by water abstracted from aquifers, via a large number of wells and boreholes. The main sources of groundwater pollution are the fertilizers used in agriculture, and the disposal of untreated wastewater from domestic and industrial use. The plain part of Almopia basin, North Greece, is a rural area with intense agricultural activities (including livestock), without significant industrial activity or urban centers. Mild touristic activity has been developed during the last decades in the area of Loutraki, due to the exploitation of the local geothermal field (Pozar springs) for balneotherapy. The aim of this paper is to evaluate the groundwater quality using conventional statistical methods, as well as to employ multivariate statistical methods (factor analysis, cluster analysis) in order to identify the main hydrogeological processes or human activities that affect and determine the water character. The area was selected because of the extended cultivating activities that take place within its boundaries and the availability of adequate data. According to the results of the implemented research, the groundwater samples are of good quality, whereas the chemical composition is mainly formed by the interaction between the water and the geological formations.
{"title":"Statistical approach of groundwater quality assessment at Almopia basin, Macedonia, North Greece.","authors":"C. Mattas, N. Veranis, G. Soulios, T. Kaklis","doi":"10.12681/bgsg.23487","DOIUrl":"https://doi.org/10.12681/bgsg.23487","url":null,"abstract":"Groundwater quality is substantial for social and economic activities in Greece since the majority of the cultivated land is irrigated by water abstracted from aquifers, via a large number of wells and boreholes. The main sources of groundwater pollution are the fertilizers used in agriculture, and the disposal of untreated wastewater from domestic and industrial use. The plain part of Almopia basin, North Greece, is a rural area with intense agricultural activities (including livestock), without significant industrial activity or urban centers. Mild touristic activity has been developed during the last decades in the area of Loutraki, due to the exploitation of the local geothermal field (Pozar springs) for balneotherapy. The aim of this paper is to evaluate the groundwater quality using conventional statistical methods, as well as to employ multivariate statistical methods (factor analysis, cluster analysis) in order to identify the main hydrogeological processes or human activities that affect and determine the water character. The area was selected because of the extended cultivating activities that take place within its boundaries and the availability of adequate data. According to the results of the implemented research, the groundwater samples are of good quality, whereas the chemical composition is mainly formed by the interaction between the water and the geological formations.","PeriodicalId":9519,"journal":{"name":"Bulletin of the Geological Society of Greece","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77952583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rzger Abdula, K. Kolo, M. Damoulianou, Victoria Raftopoulou, P. Khanaqa, S. Kalaitzidis
The aim of this study is to assess the type, thermal maturity and the petroleum generation potential of the Upper Jurassic Naokelekan Formation, occurring across the Kurdistan Region of Iraq, by applying organic petrographical methods and Rock-Eval analysis. The Rock-Eval data would indicate the presence of kerogen types III, IV and II as the main constituents. However, the qualitative petrographical evaluation revealed that the main organic constituents are solid hydrocarbons, in the form of microgranular migrabitumens, with minor amounts of pyrobitumens. These secondary particles have affected the results of the Rock-Eval analysis and would have led to misinterpretation of organic matter typification based on pyrolysis results only. The combined results of petrography and pyrolysis indicate an active petroleum system within the Upper Jurassic sequence, where hydrocarbons are generated and reservoired within suitable lithologies.
{"title":"Rock-Eval analysis and organic petrographical characterization of the Upper Jurassic Naokelekan Formation, northern Mesopotamian basin, Kurdistan Region-Iraq","authors":"Rzger Abdula, K. Kolo, M. Damoulianou, Victoria Raftopoulou, P. Khanaqa, S. Kalaitzidis","doi":"10.12681/BGSG.22842","DOIUrl":"https://doi.org/10.12681/BGSG.22842","url":null,"abstract":"The aim of this study is to assess the type, thermal maturity and the petroleum generation potential of the Upper Jurassic Naokelekan Formation, occurring across the Kurdistan Region of Iraq, by applying organic petrographical methods and Rock-Eval analysis. The Rock-Eval data would indicate the presence of kerogen types III, IV and II as the main constituents. However, the qualitative petrographical evaluation revealed that the main organic constituents are solid hydrocarbons, in the form of microgranular migrabitumens, with minor amounts of pyrobitumens. These secondary particles have affected the results of the Rock-Eval analysis and would have led to misinterpretation of organic matter typification based on pyrolysis results only. The combined results of petrography and pyrolysis indicate an active petroleum system within the Upper Jurassic sequence, where hydrocarbons are generated and reservoired within suitable lithologies.","PeriodicalId":9519,"journal":{"name":"Bulletin of the Geological Society of Greece","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73827062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Athos peninsula occupies the south-eastern part of the wider Chalkidiki peninsula in Central Macedonia, Greece. It is mainly built up by crystalline rocks belonging to the Serbo-Macedonian massif, traditionally constituting, along with the Rhodope massif, the Hellenic hinterland. According to the basic geological map of the peninsula, its northern part is mainly composed of marbles grouped into the Kerdyllion Unit, and biotite gneisses and two-mica gneisses grouped into the Vertiskos Unit of the Serbo-Macedonian massif, whereas the contact between the units is considered as a normal contact, although it has been re-evaluated as tectonic later on. Moreover, amphibolites and ultramafic rocks exist along with the previously mentioned rocks, making the geology and relationship between the two units much more complicated. Two detailed cross-sections and structural analysis permit us to revise the geology of the region concluding that the marbles, the amphibolite gneisses, formerly independent amphibolites, and the biotite gneisses belong to the Kerdyllion Unit that is strongly characterized by migmatization and anatexis, whereas the Vertiskos Unit is represented predominantly by two-mica gneisses that were not extensively, if at all, affected by these phenomena. Isoclinal folding and intense shearing with an overall top-to-the-S sense of shear resulted in the main fabric of the rocks and the mylonitic shear zone between the units. More importantly, the two-mica gneiss of the Vertiskos Unit is sandwiched between the rocks of the Kerdyllion Unit. We attribute both isoclinal folding and shearing to a Mesozoic tectonic event associated with an amphibolite facies metamorphism, leading to an Alpine reworking of the Serbo-Macedonian massif. This Alpine reworking continues during Eocene times with an ENE-WSW compression, giving rise to asymmetric to inverted folds, co-axially refolding pre-existing fabrics and structures. Our work strongly suggests that the overall structure and tectono-stratigraphy concerning the Vertiskos and Kerdyllion Units as well as the contact between them should not be based on the existence of the marbles, as traditionally followed up till now, but on the migmatization and anatexis processes that are almost absent from the rocks of the Vertiskos Unit.
{"title":"Geology and deformation of the Serbo-Macedonian massif in the northern part of the Athos Peninsula, Northern Greece: Insights from two detailed cross-sections","authors":"P. Neofotistos, M. Tranos, R. Heilbronner","doi":"10.12681/BGSG.22529","DOIUrl":"https://doi.org/10.12681/BGSG.22529","url":null,"abstract":"The Athos peninsula occupies the south-eastern part of the wider Chalkidiki peninsula in Central Macedonia, Greece. It is mainly built up by crystalline rocks belonging to the Serbo-Macedonian massif, traditionally constituting, along with the Rhodope massif, the Hellenic hinterland. According to the basic geological map of the peninsula, its northern part is mainly composed of marbles grouped into the Kerdyllion Unit, and biotite gneisses and two-mica gneisses grouped into the Vertiskos Unit of the Serbo-Macedonian massif, whereas the contact between the units is considered as a normal contact, although it has been re-evaluated as tectonic later on. Moreover, amphibolites and ultramafic rocks exist along with the previously mentioned rocks, making the geology and relationship between the two units much more complicated. Two detailed cross-sections and structural analysis permit us to revise the geology of the region concluding that the marbles, the amphibolite gneisses, formerly independent amphibolites, and the biotite gneisses belong to the Kerdyllion Unit that is strongly characterized by migmatization and anatexis, whereas the Vertiskos Unit is represented predominantly by two-mica gneisses that were not extensively, if at all, affected by these phenomena. Isoclinal folding and intense shearing with an overall top-to-the-S sense of shear resulted in the main fabric of the rocks and the mylonitic shear zone between the units. More importantly, the two-mica gneiss of the Vertiskos Unit is sandwiched between the rocks of the Kerdyllion Unit. We attribute both isoclinal folding and shearing to a Mesozoic tectonic event associated with an amphibolite facies metamorphism, leading to an Alpine reworking of the Serbo-Macedonian massif. This Alpine reworking continues during Eocene times with an ENE-WSW compression, giving rise to asymmetric to inverted folds, co-axially refolding pre-existing fabrics and structures. Our work strongly suggests that the overall structure and tectono-stratigraphy concerning the Vertiskos and Kerdyllion Units as well as the contact between them should not be based on the existence of the marbles, as traditionally followed up till now, but on the migmatization and anatexis processes that are almost absent from the rocks of the Vertiskos Unit.","PeriodicalId":9519,"journal":{"name":"Bulletin of the Geological Society of Greece","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90406067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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