Seismic hazard for the Trans Adriatic Pipeline (TAP). Part 2: broadband scenarios at the Fier Compressor Station (Albania)

AbstractTo ensure environmental and public safety, critical facilities require rigorous seismic hazard analysis to define seismic input for their design. We consider the case of the Trans Adriatic Pipeline (TAP), which is a pipeline that transports natural gas from the Caspian Sea to southern Italy, crossing active faults and areas characterized by high seismicity levels. For this pipeline, we develop a Probabilistic Seismic Hazard Assessment (PSHA) for the broader area, and, for the selected critical sites, we perform deterministic seismic hazard assessment (DSHA), by calculating shaking scenarios that account for the physics of the source, propagation, and site effects. This paper presents a DSHA for a compressor station located at Fier, along the Albanian coastal region. Considering the location of the most hazardous faults in the study site, revealed by the PSHA disaggregation, we model the ground motion for two different scenarios to simulate the worst-case scenario for this compressor station. We compute broadband waveforms for receivers on soft soils by applying specific transfer functions estimated from the available geotechnical data for the Fier area. The simulations reproduce the variability observed in the ground motion recorded in the near-earthquake source. The vertical ground motion is strong for receivers placed above the rupture areas and should not be ignored in seismic designs; furthermore, our vertical simulations reproduce the displacement and the static offset of the ground motion highlighted in recent studies. This observation confirms the importance of the DSHA analysis in defining the expected pipeline damage functions and permanent soil deformations

Η Ελληνική βάση δεδομένων σεισμογενών πηγών: σεισμοτεκτονικές συνέπειες για τη Βόρεια Ελλάδα

The Greek area is one of the most tectonically and seismically active regions worldwide, resulting in the occurrence of plenty active tectonic structures, some of which have been thoroughly studied, some less, while some others still remain unexplored. This results in the existence of a wide variety of data from various surveys, both in quantity and quality, which are either diffused or hidden within the voluminous literature. This heterogeneity makes finding information a difficult and time-consuming process, making the design and compilation of a geodatabase necessary. The creation of such a geodatabase in this thesis is not only useful for scientific purposes, such as the suggestion of geodynamic models or the interpretation of the seismotectonic behavior of various areas. Seismic hazard assessment, which has a direct socio-economic impact, is another important research field for which a database can be an integral tool.Two parameters of active tectonic structures that are overwhelmingly absent from the available literature and attempted to be determined in this thesis: the maximum depth to which active faults reach and the slip-rate. For the former, rheological profiles were calculated to determine the brittle-ductile transition zone, and for the latter, fundamental mathematical equations of deformation were combined with imported data from the main strain axes of the broader Aegean resulting from GPS measurements.The Greek Database of Seismogenic Sources is a multi-tool which, among other things, can be used, as attempted in this thesis, in various geodynamic-seismotectonic models, in the determination of static stresses changes and ground displacement after fault slip - seismic activity, and for the contribution to seismic hazard.Ο Ελλαδικός χώρος ανήκει στις πιο τεκτονικά και σεισμικά ενεργές περιοχές παγκοσμίως, με αποτέλεσμα να συναντάται μια πληθώρα ενεργών τεκτονικών δομών από τις οποίες κάποιες έχουν μελετηθεί ενδελεχώς, κάποιες λιγότερο, ενώ κάποιες άλλες παραμένουν ακόμα ανεξερεύνητες. Αυτό έχει ως αποτέλεσμα την ύπαρξη μιας μεγάλης ποικιλίας δεδομένων από διάφορες έρευνες, τόσο σε ποσότητα όσο και σε ποιότητα, τα οποία είναι είτε διάχυτα ή κρυμμένα μέσα στην πολυάριθμη βιβλιογραφία. Η ανομοιογένεια αυτή κάνει την ανεύρεση πληροφοριών, μια δύσκολη και χρονοβόρο διαδικασία, με αποτέλεσμα η δημιουργία μιας βάσης δεδομένων να φαίνεται αναγκαία. Η δημιουργία μιας τέτοιας γεωβάσης που επιχειρήθηκε στη παρούσα διατριβή δεν είναι χρήσιμη μόνο για επιστημονικούς σκοπούς, όπως π.χ. για τη δημιουργία γεωδυναμικών μοντέλων ή την ερμηνεία της σεισμοτεκτονικής συμπεριφοράς διαφόρων περιοχών. Η εκτίμηση της σεισμικής επικινδυνότητας, η οποία και έχει άμεσο κοινωνικοοικονομικό αντίκτυπο, είναι μία ακόμη σημαντική έρευνα για την οποία μια βάση δεδομένων μπορεί να αποτελέσει αναπόσπαστο εργαλείο.Δύο παράμετροι των ενεργά τεκτονικών δομών που συντριπτικά απουσιάζουν από τη διαθέσιμη βιβλιογραφία και επιχειρήθηκε να προσδιοριστούν στη παρούσα διατριβή είναι το μέγιστο βάθος στο οποίο τα ενεργά ρήγματα φτάνουν και ο ρυθμός ολίσθησης. Για το πρώτο πραγματοποιήθηκαν ρεολογικά προφίλ για τον προσδιορισμό της θραυσιγενούς-πλαστικής ζώνης μετάβασης και για το δεύτερο συνδυάστηκαν θεμελιώδεις μαθηματικές εξισώσεις της παραμόρφωσης με εισαγόμενα δεδομένα από τους κύριους άξονες παραμόρφωσης του Ελλαδικού χώρου που προκύπτουν από μετρήσεις GPS.Η Ελληνική Βάση Δεδομένων Σεισμογενών Πηγών αποτελεί ένα πολύ-εργαλείο το οποίο μεταξύ άλλων μπορεί να χρησιμοποιηθεί, όπως επιχειρήθηκε στη παρούσα διατριβή, σε διάφορα γεωδυναμικά-σεισμοτεκτονικά μοντέλα, στον προσδιορισμό μεταβολής στατικών τάσεων και εδαφικών μετατοπίσεων μετά από ολίσθηση-σεισμική δράση, και για τη συμβολή στη σεισμική επικινδυνότητα

Rock-falls and liquefaction related phenomena triggered by the June 8, 2008, Mw=6.4 earthquake in NW Peloponnesus, Greece

A strong earthquake (Mw=6.4) occurred in NW Peloponnesus, Greece, on June 8, 2008. The focal mechanism shows a transcurrent kinematics, and based on aftershocks distribution the causative fault is a dextral strike-slip NNE-SSW trending structure. The shock generated severe secondary environmental effects like rock-falls and liquefaction phenomena inducing structural damages and ground failures mainly along the fault strike. Evidence of liquefaction was observed in the area of Kato Achaia and Roupakia villages, while rock-falls were triggered mainly close to the epicentre at the foothills of the Skolis Mountain. Based on a quantitative methodological approach, the ground deformation and failures generated by the event have been investigated. In particular, based on an immediate post-event survey, we mapped in detail the distribution of the earthquake-induced ground failures, defining the areas prone to liquefaction and their associated potential. Moreover, a rock-fall hazard zonation in the area of Skolis Mountain has been developed based on the shadow angle approach, confirming the validity of the safety run-out distance models

The Greek Database of Seismogenic Sources (GreDaSS): state-of-the-art for northern Greece

The Greek Database of Seismogenic Sources (GreDaSS) is a repository of geological, tectonic and active-fault data for the Greek territory and its surroundings. In this report, we present the state-of-the-art of an on-going project devoted to the building of the GreDaSS, which represents the results of decades of investigations by the authors and a myriad of other researchers working on the active tectonics of the broader Aegean Region. The principal aim of this international project is to create a homogeneous framework of all of the data relevant to the seismotectonics, and especially the seismic hazard assessment, of Greece and its surroundings, as well as to provide a common research platform for performing seismic hazard analyses, modeling and scenarios from specific seismogenic structures. In particular, we introduce and synthetically describe the results obtained (and included in the database) to date in the northern sector of continental Greece and the Aegean Sea. As a first step we collected all available (both published and unpublished) historical and instrumental seismicity data relevant to the determining of the causative faults. Following the experience of recent 'surprising' earthquakes (e.g. 1995 Kozani, and 1999 Athens), we realized the deficiency of such an approach, and decided to also include in the GreDaSS active faults (i.e. seismogenic sources) recognized on the basis of geological, structural, morphotectonic, paleoseismological and geophysical investigations. A second step is the critical analysis of all of the collected data for the extraction of the necessary seismotectonic information, enabling the recognition of as many seismogenic sources as possible, as well as their characterization and parameterization. The most updated version of the database consists of numerous seismogenic sources that are categorized into three types: composite, individual, and debated. In this report, we describe the major seismotectonic properties of all of the composite seismogenic sources and individual seismogenic sources in northern Greece, which imply the partitioning of the area into five sectors that show similar internal behavior. Northern Greece was chosen as a pilot area because the parameters and accompanied metadata of its seismogenic sources show a high level of confidence and completeness. The amount of information and the degree of uncertainty is different for the three types.

Rock-falls and liquefaction related phenomena triggered by the June 8, 2008, Mw=6.4 earthquake in NW Peloponnesus, Greece

A strong earthquake (Mw=6.4) occurred in NW Peloponnesus, Greece, on June 8, 2008. The focal mechanism shows a transcurrent kinematics, and based on aftershocks distribution the causative fault is a dextral strike-slip NNE-SSW trending structure. The shock generated severe secondary environmental effects like rock-falls and liquefaction phenomena inducing structural damages and ground failures mainly along the fault strike. Evidence of liquefaction was observed in the area of Kato Achaia and Roupakia villages, while rock-falls were triggered mainly close to the epicentre at the foothills of the Skolis Mountain. Based on a quantitative methodological approach, the ground deformation and failures generated by the event have been investigated. In particular, based on an immediate post-event survey, we mapped in detail the distribution of the earthquake induced ground failures, defining the areas prone to liquefaction and their associated potential. Moreover, a rock-fall hazard zonation in the area of Skolis Mountain has been developed based on the shadow angle approach, confirming the validity of the safety run-out distance models

Antimony’s Significance as a Critical Metal: The Global Perspective and the Greek Deposits

Antimony is widely acknowledged as a critical raw material of worldwide significance, based on its recognition by many countries. According to current projections, there is an anticipated increase in the demand for antimony in the forthcoming years. An issue of significant concern within the supply chain, which poses a substantial obstacle to sustainable development, is the global unequal allocation of abundant antimony resources. Most nations exhibited a high degree of dependence on a few countries for their net imports of antimony, resulting in a notable disruption and raising concerns regarding the supply chain. In most countries, antimony exploration and exploitation have been paused for a long period due to financial constraints associated with operations and environmental concerns. Nowadays, identifying additional antimony reserves, particularly in countries that heavily rely on new technologies and use significant amounts of antimony, is imperative and presents a pressing endeavor. Greece is recognized as one of the European Union member states with identified antimony deposits and a historical record of antimony exploitation. A thorough description, examination, and re-assessment of all existing data on the deposits and occurrences of antimony in Greece is presented. Most of Greece’s antimony deposits are related to hydrothermal processes, controlled by specific tectonic structures, and associated with Cenozoic magmatism. They are classified either as simple Sb-deposits, where the primary ore is a stibnite mineral, or complex polymetallic deposits with varying contents that include antimony minerals

The Geological Structure and Tectonic Complexity of Northern Thessaly That Hosted the March 2021 Seismic Crisis

Knowing the rich presence of active faults in northern Thessaly and the lack of any significant seismic activity since at least the mid-1940s, the 2021 seismic sequence did not surprise us. What did surprise us was the fact that (i) despite the great knowledge of the neotectonic faults in the area, the causative faults were unknown, or almost unknown; (ii) the direction of the 2021 faulting was different than the expected, and given that the focal mechanisms showed almost pure normal dip-slip motion, the extensional main axis was also different than the one we thought we knew for this area; and (iii) besides the co-seismic ruptures that occurred within the Domeniko-Amouri basin and along the Titarissios River valley, there is evidence of rupturing in the alpine basement of Zarkos mountains. After thoroughly reviewing both the alpine and neotectonic structural setting and all the available literature concerning the seismotectonic data and interpretations of the 2021 sequence, including investigations of our own, we end up in a complex tectonic setting with older alpine structures now operating as inherited faults, and we also suggest the possible occurrence of a roughly N-dipping, low-angle, detachment-type fault. This fault runs below Mt Zarkos, reaching at least the Elassona Basin, with splay faults bifurcating upwards from the main fault zone. Following this complexity, rupture of the first mainshock must have chosen a split route reaching the surface through the gneiss rocks of Zarkos and almost (?) reaching the basinal sediments of the local tectonic depressions. This seismic sequence is a perfect case study to shed some light on the tectonic and rupture processes in the context of both geodynamics and seismic hazard assessment

Seismic Hazard Assessment for the protection of Cultural Heritage in Greece: Methodological approaches for National and Local Scale assessment (pilot areas of Aighio, Kalamata and Heraklion)

The rich Greek cultural heritage has been always threatened by the intense seismic activity in the broader Aegean region. Τhe objective of the presented project is to develop an integrated tool for the engineers in order to protect the Greek monuments, museums and archaeological sites against strong earthquakes. In order to achieve this goal a GIS-based database was developed with a bidirectional purpose: to collect and combine all necessary data about the monuments and their regional geological and seismotectonic conditions and to assess seismic hazard for each and every monument using the most modern techniques. In this paper we present the structure and development of our database, we propose a methodological procedure for estimating seismic hazard in Greece which will be the basis for the structural assessment of historical structures. The preliminary results show that the estimated values of maximum ground acceleration, in several areas nearby large faults exceed those proposed by the earthquake protection code of Greece by a significant amount. Therefore an update of the protection code would be necessary. Subsequently the estimated values of maximum ground acceleration have been applied to three cases of monuments for the determination of the most vulnerable parts of the structure and the verification of the observed pathology