Magnitude Scales in Central Greece

Κaviris, George; Papadimitriou, P.; Μακρόπουλος, Κ.

doi:10.12681/bgsg.16838

Cited by 12 publications

(7 citation statements)

References 23 publications

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“…2). More specifically, all the event locations were calculated using manually picked P-and S-wave arrival-times, the HYPOINVERSE algorithm [28] a regional 1-D velocity model, while the duration magnitude was calculated according to the formula described by relevant studies [28] [10]. A subset of the data catalogue corresponds to the Paliki (2014) and Lefkas (2015) earthquake sequence, in the vicinity of CLTFZ.…”

Section: Methodsmentioning

confidence: 99%

Cephalonia-lefkas Transform Fault Zone (CLTFZ) Complexity: Insights from 2015 Lefkas Earthquake Sequence

Karakonstantis

Pavlou

Kapetanidis

et al. 2019

JGEESI

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In order to define a better model for the Cephalonia-Lefkas Transform Fault Zone the sequence of 2015 Lefkas earthquake was examined. On 17 November 2015 (07:10 GMT) a major earthquake (Mw=6.4) occurred on the central-western part of Lefkas island. Several destructive events were located in the past in this fault zone, so an extensive seismotectonic study is feasible for that area. Manual analysis was performed using a custom velocity model that was determined for that purpose, applying the average travel-time residuals and location uncertainties errors minimization method. Several clusters belonging to the aftershock sequence were identified, whereas three are directly related to the causative fault, covering an area of about 25 km. The central one, which includes the mainshock, comprises of only a few aftershocks. The northern, within which the majority of aftershocks are located, lies in the central part of Lefkas island and the southern occurred close to the SW edge of the island. In addition, offshore clusters with distinct characteristics have been identified to the south, between Lefkas and Cephalonia islands. The temporal evolution of the aftershock sequence indicates that no migration was observed, given that after the occurrence of the mainshock the entire epicentral area was activated. Focal mechanisms of the Seismological Laboratory of the University of Athens showed dextral strike-slip faulting for both mainshock and major aftershocks of the sequence. Taking into account the spatial distribution of the aftershocks, supported by the tectonic and geomorphological settings of the region, a deformation pattern, consisting of the Cephalonia-Lefkas and Ithaca-Lefkas major fault zones which converge in the area of Vassiliki bay is proposed. The appearance of the southernmost clusters was interpreted by the positive Coulomb stress changes transfer due to major earthquake Mw=6.4.

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Section: Methodsmentioning

confidence: 99%

Cephalonia-lefkas Transform Fault Zone (CLTFZ) Complexity: Insights from 2015 Lefkas Earthquake Sequence

Karakonstantis

Pavlou

Kapetanidis

et al. 2019

JGEESI

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“…Initial locations for the earthquake sequence were acquired using the HypoInverse code [57], employing the P-wave velocity model of [58] for the neighboring Eastern Gulf of Corinth, as well as for Boeotia, obtained from recordings of the local CORNET network [59][60][61]. Other velocity models that were tried out (e.g., regional models for Central Euboea or Atalanti; [62]) provided similar results and comparable uncertainties; however, the [58] model was preferred for consistency with previous results for the 2020 Kallithea sequence, where the same model was used [36]. The importance of local velocity models for earthquake location has recently been demonstrated in the case of the 2019 Constance Lake (Central Europe) seismic sequence [63].…”

Section: Location and Relocation Of Seismicitymentioning

confidence: 99%

Investigation of the Thiva 2020–2021 Earthquake Sequence Using Seismological Data and Space Techniques

et al. 2022

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We investigate an earthquake sequence involving an Mw = 4.6 mainshock on 2 December 2020, followed by a seismic swarm in July–October 2021 near Thiva, Central Greece, to identify the activated structures and understand its triggering mechanisms. For this purpose, we employ double-difference relocation to construct a high-resolution earthquake catalogue and examine in detail the distribution of hypocenters and the spatiotemporal evolution of the sequence. Furthermore, we apply instrumental and imaging geodesy to map the local deformation and identify long-term trends or anomalies that could have contributed to stress loading. The 2021 seismic swarm was hosted on a system of conjugate normal faults, including the eastward extension of the Yliki fault, with the main activated structures trending WNW–ESE and dipping south. No pre- or coseismic deformation could be associated with the 2021 swarm, while Coulomb stress transfer due to the Mw = 4.6 mainshock of December 2020 was found to be insufficient to trigger its nucleation. However, the evolution of the swarm is related to stress triggering by its major events and facilitated by pore-fluid pressure diffusion. The re-evaluated seismic history of the area reveals its potential to generate destructive Mw = 6.0 earthquakes; therefore, the continued monitoring of its microseismicity is considered important.

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“…To homogenize the magnitudes, we used the relations proposed by [43,44] for converting to Mw. Then, we searched for waveform data in the archive of the Geodynamic Institute of the National Observatory of Athens (GI-NOA) through their EIDA node.Their database includes recordings provided by several Greek institutes, recorded by stations of the Hellenic Unified Seismological Network (HUSN) [45], and initially selected 33suitable stations, including 24 velocimeters and 9 accelerometers.The GI-NOA node also includes detailed station metadata, such as the response functions of both velocimeters and accelerometers [46]. We set a maximum event search radius of 100.0 km around each station of interest.…”

Section: Seismotectonic Setting Data Acquisition and Processingmentioning

confidence: 99%

Estimation of Earthquake Early Warning Parameters for Eastern Gulf of Corinth and Western Attica Region (Greece). First Results

Vallianatos

Karakonstantis

Sakelariou

2021

Sensors

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The main goal of an Earthquake Early Warning System (EEWS) is to alert before the arrival of damaging waves using the first seismic arrival as a proxy, thus becoming an important operational tool for real-time seismic risk management on a short timescale. EEWSs are based on the use of scaling relations between parameters measured on the initial portion of the seismic signal after the arrival of the first wave. To explore the plausibility of EEWSs around the Eastern Gulf of Corinth and Western Attica, amplitude and frequency-based parameters, such as peak displacement (Pd), the integral of squared velocity (IV 2) and the characteristic period (τc), were analyzed. All parameters were estimated directly from the initial 3 s, 4 s, and 5 s signal windows (tw) after the P arrival. While further study is required on the behavior of the proxy quantities, we propose that the IV 2 parameter and the peak amplitudes of the first seconds of the P waves present significant stability and introduce the possibility of a future on-site EEWS for areas affected by earthquakes located in the Eastern Gulf of Corinth and Western Attica. Parameters related to regional-based EEWS need to be further evaluated.

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Magnitude Scales in Central Greece

Cited by 12 publications

References 23 publications

Cephalonia-lefkas Transform Fault Zone (CLTFZ) Complexity: Insights from 2015 Lefkas Earthquake Sequence

Cephalonia-lefkas Transform Fault Zone (CLTFZ) Complexity: Insights from 2015 Lefkas Earthquake Sequence

Investigation of the Thiva 2020–2021 Earthquake Sequence Using Seismological Data and Space Techniques

Estimation of Earthquake Early Warning Parameters for Eastern Gulf of Corinth and Western Attica Region (Greece). First Results

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