Focal mechanisms of shallow and intermediate depth earthquakes along the Hellenic Arc

Benetatos, Christoforos; Kiratzi, Anastasia; Papazachos, C. B.; Karakaisis, G. F.

doi:10.1016/j.jog.2004.02.002

Cited by 109 publications

(81 citation statements)

References 29 publications

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“…The orientation of the smallest principal stress is thus significantly oblique with respect to the strike of the Hellenic arc at this part (see Figure 1). This is incompatible with the interpretation given by Benetatos et al (2004) who analysed focal mechanisms of the Aegean region. They found EW-extension for the eastern Hellenic arc and interpret this as along-arc extension (their Figures 5+6).…”

Section: Discussioncontrasting

confidence: 77%

“…Furthermore, non-uniform methods were used to determine the fault plane solutions (for description of methods used to determine the fault plane solutions in the individual studies we refer to the relevant article or webpage). Only some authors (Taymaz et al, 1990;Benetatos et al, 2004) give information on the accuracy of their fault mechanisms which was considered when skipping multiple-occurring events (see below). However, we assume having good control on the error bounds as we can compare the solutions from different sources for the same event in a number of cases.…”

Section: Data Base and Procedures Appliedmentioning

confidence: 99%

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Deformation and stress regimes in the Hellenic subduction zone from focal Mechanisms

2005

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Fault plane solutions for earthquakes in the central Hellenic arc are analysed to determine the deformation and stress regimes in the Hellenic subduction zone in the vicinity of Crete. Fault mechanisms for earthquakes recorded by various networks or contained in global catalogues are collected. In addition, 34 fault plane solutions are determined for events recorded by our own local temporary network on central Crete in [2000][2001]. The entire data set of 264 source mechanisms is examined for types of faulting and spatial clustering of mechanisms. Eight regions with significantly varying characteristic types of faulting are identified of which the upper (Aegean) plate includes four. Three regions contain interplate seismicity along the Hellenic arc from west to east and all events below are identified to occur within the subducting African lithosphere. We perform stress tensor inversion to each of the subsets in order to determine the stress field. Results indicate a uniform N-NNE direction of relative plate motion between the Ionian Sea and Rhodes resulting in orthogonal convergence in the western forearc and oblique (40-50°) subduction in the eastern forearc. There, the plate boundary migrates towards the SE resulting in left-lateral strike-slip faulting that extends to onshore Eastern Crete. N110°E trending normal faulting in the Aegean plate at this part is in accordance with this model. Along-arc extension is observed on Western Crete. Fault plane solutions for earthquakes within the dipping African lithosphere indicate that slab pull is the dominant force within the subduction process and interpreted to be responsible for the roll-back of the Hellenic subduction zone.

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Section: Discussioncontrasting

confidence: 77%

Section: Data Base and Procedures Appliedmentioning

confidence: 99%

Deformation and stress regimes in the Hellenic subduction zone from focal Mechanisms

2005

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“…Strike-slip faulting (black colour) with a significant thrust component is found along subducted Benioff zone, in accordance with earlier studies (e.g. Papazachos et al, 2000, Benetatos et al, 2004, with the P-axes running almost parallel to the strike of the arc. A new feature is that the T axεs of deeper events (>100km) become almost horizontal under the volcanic arc, not showing down-dip extension as in earlier studies for shallower events (60-100km).…”

Section: Figure 8 -Average Focal Mechanisms Using the Approach Of Papsupporting

confidence: 90%

“…We also used data from the Euro Mediterranean Seismological Center (EMSC) and Harvard (CMT solutions) databases from 2003 to 2011, as well as solutions published in a large number of previous studies (e.g. Papazachos et al, 1983;Benetatos et al, 2004;Kiratzi and Louvari, 2003;Taymaz et al,1991;Louvari et al, 1999;Kiratzi et al,1991;Yilmazturk and Burton, 1999;Arvidsson & Ekstrom, 1998;Bernard et al, 1997;Louvari et al, 2001;Kiratzi and Louvari, 2003;Vamvakaris et al, 2006). …”

Section: Data Usedmentioning

confidence: 99%

“…The subduction is associated with the generation of volcanic activity along the Hellenic volcanic arc in southern Aegean (Fytikas et al, 1985), with the volcanic centre of Santorini in Central Cyclades, being the most active volcano of the area. Much work has been already done on active tectonics of the southern Aegean (Papazachos and Comninakis, 1971;McKenzie, 1970McKenzie, , 1978Hatzfeld et al, 1989;Benetatos et al, 2004;LePichon et al, 1995;Reilinger et al, 1997;Papazachos, 1999;McClusky et al, 2000;among others). Due to the tectonic complexity of the Aegean Sea we employed recent seismological data from the EGELADOS temporary network (October 2005-April 2007 to study the active tectonics in southern Aegean.…”

Section: Introductionmentioning

confidence: 99%

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Re-examining the stress field of the broader southern Aegean subduction area using an updated focal mechanism database

Kkallas¹,

Papazachos²,

Scordilis³

et al. 2017

geosociety

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We have employed the data of EGELADOS temporary network (October 2005-April 2007) to determine 88 focal mechanism solutions from Southern Aegean Sea using the RAPIDINV algorithm (Cesca et al., 2010). The new focal mechanism solutions determined, complemented with the previously available ones for Southern Aegean Seα provide the basis for a detailed examination of the stress field, using the distribution of P and T axes. To obtain the stress field we applied the method of Gephart and Forsyth (1984), namely the grid search inversion approach of Gephart (1990a,b), which incorporates the P and T axes of selected focal mechanisms. For the inversion, the initial stress solutions were computed by the “average” kinematic P and T-axis approach of Papazachos and Kiratzi (1992). The stress-inversion allows choosing the "ideal" fault plane corresponding to the minimum misfit rotation about an axis of general orientation which is needed to match an observed fault plane/slip direction with one consistent with the final stress model.

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Present‐day crustal stress field in Greece inferred from regional‐scale damped inversion of earthquake focal mechanisms

et al. 2017

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In this study we utilize regional and teleseismic earthquake moment tensor solutions in order to infer the contemporary crustal stress in the Greek region. We focus on crustal earthquakes and select only solutions with good waveform fits and well‐resolved nodal planes. A data set of 1614 focal mechanisms is used as input to a regional‐scale damped stress inversion algorithm over a grid whose node spacing is 0.35°. Several resolution and sensitivity tests are performed in order to ascertain the robustness of our results. Our findings show that for most of the Greek region the largest principal stress σ1 is vertically oriented and that the minimum principal stress axis σ3 are subhorizontal with a predominant N‐S orientation. In the SW Peloponnese the orientation of σ3 axes rotates clockwise and in SE Aegean counterclockwise. These results are in agreement with the generally accepted model that slab rollback combined with gravitational spreading of the Aegean lithosphere are the main causes of the extension. Transitions between different faulting types in NW Greece or in the Aegean occur within narrow zones in the order of tens of kilometers. A visual comparison of the principal horizontal stress axes and the principal strain axes derived from GPS observations shows good agreement, suggesting that the crust in the Greek region behaves largely in an elastic manner.

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Focal mechanisms of shallow and intermediate depth earthquakes along the Hellenic Arc

Cited by 109 publications

References 29 publications

Deformation and stress regimes in the Hellenic subduction zone from focal Mechanisms

Deformation and stress regimes in the Hellenic subduction zone from focal Mechanisms

Re-examining the stress field of the broader southern Aegean subduction area using an updated focal mechanism database

Present‐day crustal stress field in Greece inferred from regional‐scale damped inversion of earthquake focal mechanisms

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