Thesis (M.S. in civil engineering)--Washington State University, December 2005. / Includes bibliographical references.

Thesis (Ph. D.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references. Also available via the World Wide Web.

Thesis (M.E.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references. Also available via the World Wide Web.

Την 8η Ιουνίου 2008, στις 15:25 τοπική ώρα (12:25 GMT) ένας σεισμός μεγέθους Mw 6.4 εκδηλώθηκε στη ΒΔ Πελοπόννησο, στη Δυτική Ελλάδα. Το επίκεντρο προσδιορίστηκε κοντά στο χωριό Μιχόι, στη Δημοτική Ενότητα Μόβρης, περίπου 35 km ΝΔ της Πάτρας. Στην παρούσα εργασία, έγινε μία μελέτη ανισοτροπίας στην επικεντρική περιοχή του σεισμού της 8ης Ιουνίου. Συγκεκριμένα, έγινε μία μελέτη για την ανίχνευση του φαινομένου διαχωρισμού των εγκαρσίων κυμάτων και της εξέλιξής του σε σχέση με την εκδήλωση του σεισμού της 8ης Ιουνίου. Χρησιμοποιήθηκαν οι καταγραφές από τον σεισμολογικό σταθμό του Ριόλου (RLS), καθώς είναι ο μόνος κοντινός σταθμός στο επίκεντρο του σεισμού της 8ης Ιουνίου που βρισκόταν σε συνεχή λειτουργία κατά τα χρονικά διαστήματα πριν και μετά την εκδήλωση του σεισμού. Για τη μελέτη του φαινομένου του διαχωρισμού των εγκαρσίων κυμάτων χρησιμοποιήθηκε η μέθοδος cross-correlation (Ando et al., 1983; Fukao, 1984). Μετά την επεξεργασία των δεδομένων, προσδιορίστηκαν οι παράμετροι του φαινομένου, φ (διεύθυνση ταλάντωσης της ταχύτερης συνιστώσας των εγκαρσίων κυμάτων) και dt (χρόνος καθυστέρησης μεταξύ των δύο συνιστωσών) για κάθε ένα σεισμικό γεγονός. Ο διαχωρισμός των εγκαρσίων κυμάτων (shear-wave splitting) είναι ένα φαινόμενο κατά το οποίο, τα εγκάρσια κύματα διαχωρίζονται σε δύο συνιστώσες, με διαφορετικές διευθύνσεις πόλωσης και διαφορετικές ταχύτητες διάδοσης. Ο διαχωρισμός αυτός πραγματοποιείται κατά την διάδοση των εγκαρσίων κυμάτων μέσα από ένα ανισοτροπικό μέσο (Crampin and Chastin, 2003; Crampin and Peacock, 2005). Σύμφωνα με τη θεωρία, ο διαχωρισμός των εγκαρσίων κυμάτων στον φλοιό, προκαλείται εξαιτίας της ύπαρξης μικρο-ρωγμών, μικρο-διαρρήξεων κορεσμένων με ρευστά. Οι μικρο-διαρήξεις αυτές έχουν συνήθως διευθύνσεις παράλληλες ή υπό-παράλληλες με αυτή της μέγιστης οριζόντιας συμπιεστικής τάσης σε μία περιοχή (Crampin, 1993). Η ανάλυση των δεδομένων κατέδειξε την ύπαρξη του φαινομένου διαχωρισμού των εγκαρσίων κυμάτων στην υπό μελέτη περιοχή. Τόσο πριν, όσο και μετά την εκδήλωση του σεισμού της 8ης Ιουνίου, οι διευθύνσεις πόλωσης της ταχύτερης συνιστώσας των εγκαρσίων κυμάτων ακολουθούν μία μέση διεύθυνση ΒΒΔ-ΝΝΑ. Η μέση διεύθυνση της ταχύτερης συνιστώσας δεν είναι σύμφωνη με τα χαρακτηριστικά του πεδίου των τάσεων στην περιοχή, όπως προσδιορίστηκαν από τους Konstantinou et al. (2011) και Hollenstein et al. (2008), με μία μέση διεύθυνση οριζόντιας συμπιεστικής τάσης Α-Δ. Η ΒΒΔ-ΝΝΑ διεύθυνση πόλωσης της ταχύτερης συνιστώσας οφείλεται πιθανόν στη δράση ενός πεδίου τάσεων γύρω και κάτω από τη θέση καταγραφής με τοπικά χαρακτηριστικά. Τέλος, παρατηρήθηκε μία αύξηση στις τιμές των χρόνων καθυστέρησης μετά την εκδήλωση του σεισμού της 8ης Ιουνίου. Η μέση τιμή των χρόνων καθυστέρησης πριν την εκδήλωση του σεισμού ήταν περίπου 27.3 ms, ενώ μετά την εκδήλωσή του 41.7 ms. H αύξηση των χρόνων καθυστέρησης, υποδηλώνει μία μεταβολή των ιδιοτήτων του μέσου στον ανώτερο φλοιό εξαιτίας της εκδήλωσης του σεισμού. Η εκδήλωση του σεισμού της 8ης Ιουνίου προκάλεσε πιθανόν την διεύρυνση και την επιμήκυνση των προϋπαρχόντων μικρο-διαρρήξεων του φλοιού, τη δημιουργία νέων και την επιπλέον πλήρωσή τους με ρευστά. / On June 8, 2008, at 15:25 local time (12:25 GMT) an Mw 6.4 earthquake occurred in the area of northwest Peloponnesus, Western Greece. The epicenter was located near Mihoi village, in the municipality of Movri, about 35 km southwest of Patras. In this paper, a crustal anisotropy analysis was performed in the epicentral area of Movri Mountain earthquake. Specifically, there was a study to detect shear-wave splitting phenomenon and its temporal evolution in relation to the occurrence of Movri Mountain earthquake. For the needs of the study, we used seismic records from the seismological station of Riolos (RLS). Riolos station is the nearest station from the epicenter of Movri Mountain earthquake which was in continuous operation during the periods before and after the occurrence of the earthquake. The method that was used to study shear-wave splitting phenomenon was the cross-correlation method (Ando et al., 1983; Fukao, 1984; Kuo et al., 1994). Through the data processing, splitting parameters φ (polarization direction of the fastest component of shear waves) and dt (time delay between the two components) were measured for each seismic event. Shear-wave splitting is a phenomenon in which shear-waves are separated into two components with different polarization directions and velocities. The phenomenon in the upper crust is caused by the existence of stress-aligned, fluid-filled micro-cracks/micro-fractures. The polarization directions of the fast components are usually parallel or sub-parallel to the direction of the maximum horizontal compressive stress (Crampin, 1993). Data analysis revealed the existence of shear-wave splitting phenomenon in the study area. Both before and after the occurrence of Movri Mountain earthquake, the polarization directions of the fast component of shear waves follow a general NNW-SSE direction. The observed mean fast polarization direction is not consistent with the estimated characteristics of the regional stress field of the broader area, as identified by Kontsantinou et al. (2011) and Hollenstein et al. (2008), who report a general E-W direction of the maximum horizontal compressive stress. The difference between the estimated fast polarization directions and the properties of the regional stress field shows the presence of a local stress field in the study area. Finally, an increase in time delays was observed after the occurrence of Movri Mountain earthquake. The average value of delay times before the occurrence of the earthquake was about 27.3ms, while after the occurrence was about 41.7ms. The increase in delay times which was observed after the occurrence of Movri Mountain earthquake possibly indicates changes in the properties of the medium in the upper crust. The occurrence of Movri Mountain earthquake caused the expansion/ lengthening of micro-cracks and its further filling with fluids.

L'existence de glissements lents a été observé pour la première fois en Californie, sur une portion de la faille de San Andreas (Steinbrugge et al., 1960,Tocher 1960). Ils ont ensuite été détéctés dans les années 90s avec l'avènement des GPS. Les interactions entre glissement lents, ou glissements asismiques (qui n'émettent pas d'ondes élastiques) et les glissements sismiques est cependant mal connue.Pourtant, cette question est fondamentale puisque des glissements lents ont été observés avant plusieurs séismes.Par exemple, l’installation d’un glissement lent avant le séisme d’Izmit de 1999 en Turquie a été mise en évidence grâce à l’analyse de signaux répétitifs (Bouchon et al., 2011). De même, en étudiant le comportement des séismes répétitifs avant le méga-séisme de Tohoku de 2011, deux séquences de glissement lent en direction du point d’initiation ont été observées (Kato et al., 2012). D’autres glissements lents précédents des séismes de grandes ampleurs ont été reportés, notamment au Mexique, avant le séisme de Papanoa (Radiguet et al., 2016) de magnitude 7.3 et au Chili, avant le séisme d’Iquique de 2014 de magnitude 8.2 (Ruiz et al., 2014).L'objectif de ce travail de thèse est de mieux caractériser les interactions qui existent entre glissements sismiques et asismiques dans une zone de subduction très largement instrumentée: le Japon.La très grande densité des réseaux Japonais (sismique courte et longue période, GPS) autorise des seuils de détection des glissements sismiques ou lents très bas, et permet d'utiliser des méthodes de réseaux afin de maximiser le rapport signal sur bruit. La recherche d'épisodes de déformation lente est basée sur plusieurs types d'observables et de méthodes, et est complétée par l'analyse des changements de taux de sismicité accompagnant ces épisodes. Cette thèse vise ainsi à mieux comprendre comment du glissement lent peut -ou non- accélérer l'occurrence de grands séismes, et les conditions requises pour se faire. / Transient aseismic slip events (that do not emit elastic waves) were first discovered on the San Andreas fault in central California in 1960 (Steinbrugge et al., 1960, Tocher 1960) and were later confirmed by the development and installation of GPS stations. Aseismic slip can occur on continental faults as well as on subduction zones. However, the interactions between aseismic and seismic slips are not fully captured yet. Understanding the mechanisms at stake on fault planes is fundamental since several large earthquakes were preceded by aseismic slip episodes.For example, the setting of a slow slip event before the 1999 Izmit earthquake in Turkey was evidenced by the observation of repeating signals at one station (Bouchon et al., 2011). Also, by studying repeating earthquakes before the 2011 Tohoku earthquake, two slow slip episodes that migrated towards the rupture intitiation were observed (Kato et al., 2012). Other transient slips preceding large earthquakes occurred, including in Mexico, before the M7.3 Papanoa earthquake (Radiguet et al., 2016) and in Chile, before the 2014 Iquique earthquake (Ruiz et al., 2014).The aim of this thesis is to better characterize the interactions between seismic and aseismic slip that can occur in a subduction zone largely instrumented: Japan.The very high density of the japanese monitoring networks(seismic networks, both at short and long periods, and GPS network), allows the detection ofseismic and aseismic slip events with low intensity / size, and is amenable to the use of arraymethods to improve the signal-to-noise ratio. The search for episodes of transient deformation will be based on several observables andtechniques, and is complemented by the analysis of the changes in earthquake rates concomittent to these episodes. This work thus gives new clues on how aseismic deformation can -or not- accelerate the occurrence of strong earthquakes, and on what are the conditions (tectonic, dynamic) for this to happen.

Les mouvements forts du sol générés par les séismes peuvent être reliés aux caractéristiques de la source sismique (chute de contrainte, vitesse de rupture, etc.), et aux conditions frictionnelles des failles. Ces caractéristiques sont généralement étudiées via l’analyse des enregistrements accélérométriques des grands séismes à basses fréquences (≤ 1 Hz). L'amélioration des réseaux accélérométriques a permis l’enregistrement de nombreux séismes de magnitudes faibles et modérées (Mw ≤ 6,0). Ces enregistrements contiennent des informations dans la bande de hautes fréquences (1 Hz - 50 Hz), qui ne peuvent pas être exploitées avec les méthodes sismologiques classiques.Pour exploiter ces données de mouvements forts des séismes de faible intensité dans l’objectif d’étudier étudier les conditions frictionnelles de l'interface de subduction, nous explorons deux méthodes pour comparer le contenu fréquentiel des séismes: la première basée sur les rapports spectraux et la deuxième basée sur les équations de prédiction du mouvement du terrain (GMPE). Ces méthodes ont été utilisées pour étudier la variabilité spatiale et temporelle du contenu fréquentiel des séismes rompant l'interface de subduction au nord du Chili et au Japon. Leurs avantages et limitations respectifs ont été analysés. Ces comparaisons méthodologiques nous ont a permis de confronter et de valider les résultats, et ainsi de proposer une nouvelle méthodologie fiable basée sur l'analyse des résidus de GMPE pour analyser le contenu fréquentiel des séismes.L'analyse des résultats obtenus a montré une dépendance avec la profondeur du contenu en fréquence des séismes de l’interface de subduction, concordant avec les observations de grandes ruptures de subduction [Lay et al., 2012]. En même temps, des variations du contenu fréquentiel des séismes ont été détectées le long de la fosse de subduction, ce qui nous a conduit à décrire une segmentation latérale de l'interface de subduction. Cette segmentation a été comparée avec la distribution spatiale de la sismicité, à la géométrie de l'interface de subduction et à ses conditions de glissement. Finalement, avant le séisme d’Iquique de 2014 (Mw 8.1) au nord du Chili, nous avons détecté une évolution temporelle du contenu en fréquence des séismes associée à l’occurrence d'un glissement lent précurseur au choc principal. / The strong ground motions generated by earthquakes can be related to the characteristics of the earthquakes source (stress drop, rupture velocity etc..), and therefore to the frictional conditions of the faults. These characteristics are usually studied by analyzing the low frequency band (≤ 1Hz) of the strong motion records of large earthquakes. The improvement of strong motion networks has generated large datasets of records of moderate and low magnitude earthquakes (Mw ≤ 6.0). These records contain informations in the high frequency band (1 Hz – 50 Hz), which cannot be exploited using classical seismological methods.In order exploit the strong motion records of low magnitude earthquakes to study the subduction interface’s frictional conditions, we explore two methods for comparing the earthquakes frequency content: the first one based on spectral ratios, and the second one based on the Ground Motion Prediction Equations (GMPEs). These methods have been used to investigate the spatial and temporal variability of the frequency content of subduction interface earthquakes in North Chile and Japan. Their respective benefits and limitations have been analyzed. These methodological comparisons allowed us to cross compare and validate the results, and to propose a new, reliable methodology based on the analysis of GMPEs residuals to compare the earthquakes frequency content.The analysis of the results showed a depth dependency of the frequency content of subduction earthquakes in agreement with the one derived from large megathrust ruptures [Lay et al., 2012]. Additionally, variations of the earthquake frequency content along trench have been detected, which may drive to a lateral segmentation of the subduction interface. This segmentation has been compared to the spatial distribution of the seismicity, the geometry of the subduction interface and its slippage conditions. Finally, before the occurrence of 2014 Iquique Earthquake Mw 8.1 in North Chile, a temporal evolution of the frequency content of the foreshocks has been detected, associated to a precursory slow slip of the subduction interface.

abstract: The San Andreas Fault (SAF) is the primary structure within a system of faults accommodating motion between the North American and Pacific plates. Physical models of faulting and characterizations of seismic hazard are informed by investigations of paleoseismology, slip distribution, and slip rate. The impact of earthquakes on people is due in large part to social vulnerability. This dissertation contributes an analysis about the relationships between earthquake hazard and social vulnerability in Los Angeles, CA and investigations of paleoseismology and fault scarp array complexity on the central SAF. Analysis of fault scarp array geometry and morphology using 0.5 m digital elevation models along 122 km of the central SAF reveals significant variation in the complexity of SAF structure. Scarp trace complexity is measured by scarp separation, changes in strike, fault trace gaps, and scarp length per SAF kilometer. Geometrical complexity in fault scarp arrays indicates that the central SAF can be grouped into seven segments. Segment boundaries are controlled by interactions with subsidiary faults. Investigation of an offset channel at Parkfield, CA yields a late Holocene slip rate of 26.2 +6.4/- 4.3 mm/yr. This rate is lower than geologic measurements on the Carrizo section of the SAF and rates implied by far-field geodesy. However, it is consistent with historical observations of slip at Parkfield. Paleoseismology at Parkfield indicates that large earthquakes are absent from the stratigraphic record for at least a millennia. Together these observations imply that the amount of plate boundary slip accommodated by the main SAF varies along strike. Contrary to most environmental justice analyses showing that vulnerable populations are spatially-tied to environmental hazards, geospatial analyses relating social vulnerability and earthquake hazard in southern California show that these groups are not disproportionately exposed to the areas of greatest hazard. Instead, park and green space is linked to earthquake hazard through fault zone regulation. In Los Angeles, a parks poor city, the distribution of social vulnerability is strongly tied to a lack of park space. Thus, people with access to financial and political resources strive to live in neighborhoods with parks, even in the face of forewarned risk. / Dissertation/Thesis / Ph.D. Geological Sciences 2011

Permettant de protéger les populations des inondations, de canaliser l'eau à des fins d'irrigation ou de production d'électricité, les digues en terre sont des ouvrages stratégiques dont la rupture peut avoir des conséquences dramatiques. La stabilité de ces ouvrages doit ainsi pouvoir être assurée, notamment en cas de séisme. Cependant, étant donné le très grand linéaire qu'ils représentent, la mise en œuvre de vastes campagnes de reconnaissances et de modèles numériques complexes n'est pas toujours envisageable dans les zones de sismicité modérée. L'utilisation d'outils simplifiés, faisant appel à des données facilement mesurables, se révèle indispensable pour fournir une indication sur la stabilité de tronçons de digue soumis à un chargement sismique. Les méthodes simplifiées existantes permettant d'estimer la réponse dynamique des remblais sont inadaptées au contexte des digues. En effet, alors que les digues sont pour la plupart construites dans des vallées sédimentaires, la majorité de ces méthodes, développées pour l’étude des barrages, supposent que l’ouvrage est fondé directement au rocher. Seules deux approches permettent de prendre en compte l’interaction entre l’ouvrage et son sol d’assise (effets de site) : la méthode de Sarma(1979) et celle de Papadimitriou(2014). Cependant, la première est basée sur des hypothèses très fortes (elle considère notamment un rocher rigide et un amortissement uniforme, qui plus est très fort) et la seconde se limite à des ouvrages ayant une hauteur supérieure à 20 si{m}. L'approche développée au cours de cette thèse repose sur des hypothèses plus réalistes, en considérant notamment des géométries adaptées à celles des digues, en prenant en compte les effets de site et en adaptant la dissipation d'énergie au niveau de sollicitation. Une étude paramétrique numérique (calcul de la réponse visco-élastique par éléments spectraux en deux dimensions) est utilisée pour couvrir un ensemble de configurations géométriques et mécaniques de digues. Pour prendre en compte la non-linéarité, les valeurs d'amortissement et de dégradation du module de cisaillement sont adaptées en chaque point des modèles à partir des résultats fournis par une série de calculs en linéaire équivalent 1D. Les réseaux de neurones artificiels, dont l'apprentissage est basé sur les résultats des simulations numériques, sont utilisés pour le développement d'une nouvelle méthode simplifiée. Des abaques sont réalisés, à partir des réseaux de neurones établis, pour offrir une alternative visuelle à leur utilisation "mathématiques". Les outils simplifiés auxquels aboutit cette thèse font appel à des paramètres facilement mesurables sur le terrain. Des méthodes géophysiques sont mises en œuvre au niveau de quatre sites de digues afin d'identifier le meilleur compromis de mesures permettant d'estimer les paramètres nécessaires à l'évaluation de la réponse dynamique de l'ouvrage. / Embankments are strategic facilities that, among other things, protect population from flooding and canalize rivers for energy production or for irrigation concerns. Since their rupture can lead to terrible consequences, they must remain stable, especially in case of earthquake. However, given the very large length of embankments, it is rarely possible to conduct complete investigations and complex numerical models in regions of moderate seismicity. Therefore, simplified tools to estimate the dynamic response of embankments using accessible embankments’ features are necessary to estimate their capacity to resist seismic loadings. Existing simplified methods, generally developed to assess the dynamic response of embankment-dams, turn out to be inappropriate to study the particular case of embankments along rivers – or other types of embankment, with small height and large length. The majority of these simplified methods do not take into account site effects: they assume the presence of rock directly at the base of the embankment, whereas most of large length embankments are located in alluvial valleys. Two methods only - Sarma(1979) and Papadimitriou(2014) - take into account the interaction between the embankment and its soil foundation. However, the first one relies on strong assumptions (among others, that the bedrock is considered rigid and that the viscous damping is supposed to be both spatially uniform and very large) and the second one is limited to tall embankments (higher than 20 si{m}).The method developed in this thesis relies on assumptions that are more realistic: it considers geometries adapted to large length embankments, it accounts for the presence of a soil foundation and includes an energy dissipation process consistent with expected levels of strain. A numerical parametric study is performed based on the computation with the spectral element method of the viscoelastic response of a large set of embankments spanning a wide range of geometrical and mechanical properties. In order to take into account nonlinearity, damping and shear modulus reduction are adapted in each point of the numerical models according to the results of a set of 1D linear equivalent computations. A new simplified method is derived from the obtained numerical results using artificial neural networks. Abacuses are produced from the neural networks so that engineers can have at their disposal a visual tool. This thesis leads to a simplified method that uses some accessible features of embankments as input parameters. The ability of classical geophysical methods to provide those input parameters is further estimated on four sites corresponding to different realistic configurations.

abstract: The dynamic Earth involves feedbacks between the solid crust and both natural and anthropogenic fluid flows. Fluid-rock interactions drive many Earth phenomena, including volcanic unrest, seismic activities, and hydrological responses. Mitigating the hazards associated with these activities requires fundamental understanding of the underlying physical processes. Therefore, geophysical monitoring in combination with modeling provides valuable tools, suitable for hazard mitigation and risk management efforts. Magmatic activities and induced seismicity linked to fluid injection are two natural and anthropogenic processes discussed in this dissertation. Successful forecasting of the timing, style, and intensity of a volcanic eruption is made possible by improved understanding of the volcano life cycle as well as building quantitative models incorporating the processes that govern rock melting, melt ascending, magma storage, eruption initiation, and interaction between magma and surrounding host rocks at different spatial extent and time scale. One key part of such models is the shallow magma chamber, which is generally directly linked to volcano’s eruptive behaviors. However, its actual shape, size, and temporal evolution are often not entirely known. To address this issue, I use space-based geodetic data with high spatiotemporal resolution to measure surface deformation at Kilauea volcano. The obtained maps of InSAR (Interferometric Synthetic Aperture Radar) deformation time series are exploited with two novel modeling schemes to investigate Kilauea’s shallow magmatic system. Both models can explain the same observation, leading to a new compartment model of magma chamber. Such models significantly advance the understanding of the physical processes associated with Kilauea’s summit plumbing system with potential applications for volcanoes around the world. The unprecedented increase in the number of earthquakes in the Central and Eastern United States since 2008 is attributed to massive deep subsurface injection of saltwater. The elevated chance of moderate-large damaging earthquakes stemming from increased seismicity rate causes broad societal concerns among industry, regulators, and the public. Thus, quantifying the time-dependent seismic hazard associated with the fluid injection is of great importance. To this end, I investigate the large-scale seismic, hydrogeologic, and injection data in northern Texas for period of 2007-2015 and in northern-central Oklahoma for period of 1995-2017. An effective induced earthquake forecasting model is developed, considering a complex relationship between injection operations and consequent seismicity. I find that the timing and magnitude of regional induced earthquakes are fully controlled by the process of fluid diffusion in a poroelastic medium and thus can be successfully forecasted. The obtained time-dependent seismic hazard model is spatiotemporally heterogeneous and decreasing injection rates does not immediately reduce the probability of an earthquake. The presented framework can be used for operational induced earthquake forecasting. Information about the associated fundamental processes, inducing conditions, and probabilistic seismic hazards has broad benefits to the society. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2018

Title: The source process of Greek earthquakes Author: Dana K ížová Department: Department of Geophysics Supervisor of the doctoral thesis: Prof. RNDr. Ji í Zahradník DrSc., Department of Geophysics Abstract: Investigations of moment tensor (MT) and its uncertainty are topical. This thesis is focused on isotropic component of three shallow earthquakes: Event A in Cretan Sea (Mw 5.3) and two events near Santorini island, B (Mw 4.9) and C (Mw 4.7). MT is inverted from full waveforms in an assumed 1D velocity model. The inverse problem is non-linear in centroid depth and time, and linear in six MT parameters, one is the MT-trace. Uncertainty of isotropic component is studied by a new approach (K ížová et al., 2013). The trace is systematically varied, and remaining parameters are optimized. The method reveals tradeoffs between the isotropic component, depth, time, and focal mechanism. From two existing velocity models, we prefer the one with lower condition number, in which a (positive) isotropic component is indicated for event B. To rapidly assess a likely existence of isotropic component, an empirical method is proposed (K ížová et al., 2016). It is based on comparison between depth- dependences of waveform correlation in full and deviatoric modes. Based on extensive synthetic tests, the method confirms a...