Rupture Process and Aftershocks Relocation of the 8 June 2008 Mw 6.4 Earthquake in Northwest Peloponnese, Western Greece

Konstantinou, Konstantinos I.; Melis, Νikolaos S.; Lee, S.-J.; Evangelidis, Christos; Boukouras, Konstantinos

doi:10.1785/0120080301

Cited by 29 publications

(16 citation statements)

References 42 publications

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“…The application is shown for the Movri Mountain earthquake, analyzed in paper 1 [see also Gallovič et al , 2009; Konstantinou et al , 2009; Cesca et al , 2010]. Here we reconsider the problem within the framework of the regularized SVD technique.…”

Section: Application To Real Datamentioning

confidence: 99%

Toward understanding slip inversion uncertainty and artifacts: 2. Singular value analysis

Gallovič¹,

Zahradnı́k²

2011

J. Geophys. Res.

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Seismic slip inversion is studied by means of singular value decomposition (SVD), with emphasis on the role of singular vectors and regularization of the solution. Because the stable part of the slip inversion result is given in terms of a linear combination of the leading singular vectors (representing directions in the model space most sensitive to data), the performance of the inversion depends simply on how well the real slip model can be expanded into these vectors. The analysis is demonstrated using a synthetic model of a symmetric bilateral rupture with two asperities. Inverting the data yields a persisting false asperity in the middle of the fault, regardless of the inversion scheme used, because such a model cannot be well represented by only the leading singular vectors. The parallel study of the singular vectors from the individual stations and the whole network is suggested in order to understand how to achieve balance between overregularized solutions (with possible slip inversion artifacts) and underregularized solutions (vulnerable to data errors). The ideas are applied to the Mw 6.3 Movri Mountain earthquake, 2008, Greece, showing a weak indication of an asymmetric bilateral rupture. We suggest that inversion methods, not working explicitly with singular vectors, may yield artifacts, the origin of which can be also often explained by the SVD technique. Therefore, practical earthquake studies should be broadly complemented by the analysis of the leading singular vectors, a simple tool to evaluate the efficiency and potential drawbacks of the slip inversion.

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Section: Application To Real Datamentioning

confidence: 99%

Toward understanding slip inversion uncertainty and artifacts: 2. Singular value analysis

Gallovič¹,

Zahradnı́k²

2011

J. Geophys. Res.

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“…The predominant slip occurred near the main shock hypocenter and at the SSW edge of the rupture area, with a maximum value of *0.8-1.0 m, at depths 21-25 km. This high slip patch occupies the deeper part of the northwestern patch, as the one suggested by Konstantinou et al (2009), although their patch is located in between *10 and 15 km. The mean slip value is suitable for the shallower rupture part, approximately to 15-20 km in depth.…”

Section: Slip Model and Displacement Fieldmentioning

confidence: 60%

“…Positive and negative changes are depicted in red and blue color, respectively. Frequency histograms of static stress changes calculated according to a the main rupture faulting type, b the faulting type assigned to the northern cluster in this study, and c with a strike of 295°T he Aftershock Sequence of the 2008 Achaia, Greece, Earthquake... previous ones (Konstantinou et al 2009;Serpetsidaki et al 2014) is that a much larger number of aftershocks (a few thousands instead of a few hundreds), for much longer period (years instead of weeks) and with exhaustive efforts for improving locations (a specific velocity model, stations delays in addition to HYPOINVERSE, double difference and cross-correlation techniques). The location uncertainties are attained to get diminutive values, supporting identification of the fine details of the activated area.…”

Section: Discussionmentioning

confidence: 94%

“…The 2008 main shock epicenter is shown by the asterisk inside a rectangle which defines our study area. KTFZ Kefalonia Transform Fault Zone, NAT North Aegean Trough fault that also coincides with the area that suffered most of the damage (Konstantinou et al 2009). Similar results were found by Zahradnik and Gallovic (2010) and particularly the large time delay of the main slip patch with respect to the origin time.…”

Section: Introductionmentioning

confidence: 99%

“…Relocation of 370 aftershocks in the period of 8 June-11 July 2008 with hypoDD and 1-D velocity model was performed by Ganas et al (2009). 438 events between 8 June until 13 July were relocated by Konstantinou et al (2009) who used catalog and differential travel times, with most aftershocks being located in areas of low slip (\25 cm) filling the regions of slip deficit. Serpetsidaki et al (2014) employed hypoDD and 1-D velocity model for the relocation of 872 events occurred in the first 4 months.…”

Section: Introductionmentioning

confidence: 99%

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The Aftershock Sequence of the 2008 Achaia, Greece, Earthquake: Joint Analysis of Seismicity Relocation and Persistent Scatterers Interferometry

Karakostas

Mirek²,

Mesimeri

et al. 2016

Pure Appl. Geophys.

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On 8 June 2008 an earthquake of M w 6.4 took place in the northwestern part of Peloponnese, Greece. The main shock was felt in a wide area and caused appreciable damage along the main rupture area and particularly at the antipodal of the main shock epicenter fault edge, implying strongly unilateral rupture and stopping phase effects. Abundant aftershocks were recorded within an area of *50 km in length in the period 8 June 2008-end of 2014, by a sufficient number of stations that secure location accuracy because the regional network is adequately dense in the area. All the available phases from seismological stations in epicentral distances up to 140 km until the end of 2014 were used for relocation with the double difference technique and waveform cross-correlation. A quite clear 3-D representation is obtained for the aftershock zone geometry and dimensions, revealing the main rupture and the activated adjacent fault segments. SAR data are processed using Stanford Method for Persistent Scatterers (StaMPS) and a surface deformation map constructed based on PS point displacement for the coseismic period. A variable slip model, with maximum slip of *1.0 m located at the lower part of the rupture plane, is suggested and used for calculating the deformation field which was found in adequate agreement with geodetic measurements. With the same slip model the static stress changes were calculated evidencing possible triggering of the neighboring faults that were brought closer to failure. The data availability allowed monitoring the temporal variation of b values that after a continuous increase in the first 5 days, returned and stabilized to 1.0-1.1 in the following years. The fluctuation duration is considered as the equivalent time for fault healing, which appeared very short but in full accordance with the cessation of onto-fault seismicity.

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Strain and rotation rate patterns of mainland Greece from continuous GPS data and comparison between seismic and geodetic moment release

2015

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We processed data from~100 continuous GPS stations to provide new insights into the crustal motion and deformation of central and western Greece. We used the derived velocity field to evaluate two-dimensional strain and rotation rate tensors, and we mapped the dilatation and maximum shear strain rates. In central Peloponnese and Epirus, we documented a 90°switch in the extension direction, which can be explained on the basis of the plate boundary configuration. Evidence for an extended deformation pattern in central Greece was found. Additionally, we detected two pairs of shear belts, one in Akarnania-NW Peloponnese and one in North Aegean. We delineated two rotational domains that dominate the present-day pattern. Moreover, we saw no geodetic evidence for North Anatolian Fault growth toward central Greece. We translated the geodetic strain rates into rates of seismic moment release and compared them with earthquake catalog-based moment rates. In the central Ionian Sea, the geodetic strain is completely released seismically, which is indicative of a fully coupled seismogenic zone. However, for most of the study area, the geodesy-based moment rates are at least 2 times higher than the earthquake-based rates. We attribute this mainly to earthquake catalog representativity over the long-term situation. However, for the Gulf of Corinth, it is unrealistic to associate the high ratio of geodetic to seismic moment rates only to incompleteness of the earthquake catalog; instead, long-term aseismic deformation must be an important mechanism accommodating a considerable portion of the strain budget, especially at its western part.

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Rupture Process and Aftershocks Relocation of the 8 June 2008 Mw 6.4 Earthquake in Northwest Peloponnese, Western Greece

Cited by 29 publications

References 42 publications

Toward understanding slip inversion uncertainty and artifacts: 2. Singular value analysis

Toward understanding slip inversion uncertainty and artifacts: 2. Singular value analysis

The Aftershock Sequence of the 2008 Achaia, Greece, Earthquake: Joint Analysis of Seismicity Relocation and Persistent Scatterers Interferometry

Strain and rotation rate patterns of mainland Greece from continuous GPS data and comparison between seismic and geodetic moment release

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