Spatiotemporal Properties of Seismicity and Variations of Shear-Wave Splitting Parameters in the Western Gulf of Corinth (Greece)

Kapetanidis, Vasilis; Michas, Georgios; Κaviris, George; Vallianatos, Filippos

doi:10.3390/app11146573

Cited by 9 publications

(8 citation statements)

References 83 publications

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“…Both the abovementioned hydraulic diffusivity and the migration rate are comparable with the respective values previously measured in fluid-associated earthquake triggering at the Western Corinth Gulf (e.g., [9,10,12,94,95]). Seismic swarms are commonly observed in areas related to volcanic activity, involving magmatic or hydrothermal fluids (e.g., the 2008-2009 swarm at Yellowstone Lake [96] or the 2008 swarm at Vogtland/NW Bohemia [97]), or induced by water injection in geothermal fields (e.g., the 1993 swarm in Soultz-sous-Foret, France [98]).…”

Section: Discussionsupporting

confidence: 86%

“…Thiva (Central Greece) is located at the transition zone between two major WNW-ESEand NW-SE-striking rifts: the Corinth Gulf in the south and the Euboekos Gulf in the east (Figure 1). The Gulf of Corinth is an area characterized by high seismicity [6,7] expressed through the frequent occurrence of seismic swarms [8][9][10][11][12]. [13] are shown, along with the locations of seismological stations of the Hellenic Unified Seismic Network (HUSN; red triangles) and GNSS stations (inverse yellow triangles).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

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

et al. 2022

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“…The sequences in the Corinth Gulf in particular are characterized by the highest background rate among the three areas (Table 5), meaning that a significant portion of clustered seismicity is not caused by the triggering of a main shock coseismic slip, but by the contribution of different triggering mechanisms. Many studies have focused on this area, suggesting pore-pressure changes due to fluid migration and aseismic creep as possible triggering mechanisms for the clustered seismicity [57,71]. In the North Aegean Sea, the swarm activity coexists with aftershock sequences, implying that for forecasting purposes, a finer regionalization might be more appropriate.…”

Section: Discussionmentioning

confidence: 99%

“…Nevertheless, there is a slight decrease in the occurrence of earthquakes (λ 1 = 1.23 events/day) in the second part of the catalog, starting from 02/2016 with transitions to state 1 (red color, Figure 3a) until almost the end of the catalog in 12/2019. This is probably related to the lack of seismic sequences during the last part of the study period compared to the previous intense seismic activity especially during the period 2013-2014 in the western subarea of the CG [57]. The rate threshold is set equal to λ thr = λ 2 , which we consider as the background rate during the study period.…”

Section: Triggered and Background Seismicity Separationmentioning

confidence: 99%

Identification and Temporal Characteristics of Earthquake Clusters in Selected Areas in Greece

2022

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The efficiency of earthquake clustering investigation is improved as we gain access to larger datasets due to the increase of earthquake detectability. We aim to demonstrate the robustness of a new clustering method, MAP-DBSCAN, and to present a comprehensive analysis of the clustering properties in three major seismic zones of Greece during 2012–2019. A time-dependent stochastic point model, the Markovian Arrival Process (MAP), is implemented for the detection of change-points in the seismicity rate and subsequently, a density-based clustering algorithm, DBSCAN, is used for grouping the events into spatiotemporal clusters. The two-step clustering procedure, MAP-DBSCAN, is compared with other existing methods (Gardner-Knopoff, Reasenberg, Nearest-Neighbor) on a simulated earthquake catalog and is proven highly competitive as in most cases outperforms the tested algorithms. Next, the earthquake clusters in the three areas are detected and the regional variability of their productivity rates is investigated based on the generic estimates of the Epidemic Type Aftershock Sequence (ETAS) model. The seismicity in the seismic zone of Corinth Gulf is characterized by low aftershock productivity and high background rates, indicating the dominance of swarm activity, whereas in Central Ionian Islands seismic zone where main shock-aftershock sequences dominate, the aftershock productivity rates are higher. The productivity in the seismic zone of North Aegean Sea vary significantly among clusters probably due to the co-existence of swarm activity and aftershock sequences. We believe that incorporating regional variations of the productivity into forecasting models, such as the ETAS model, it might improve operational earthquake forecasting.

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“…The use of the freely available CRL data highlighted that most seismicity is clustered, with the frequent occurrence of swarms, as the 2001 Agios Ioannis [Pacchiani and Lyon-Caen, 2010], the 2013 Helike [Kapetanidis et al, 2015[Kapetanidis et al, , 2021Kaviris et al, 2017] and the 2015 Malamata [De Barros et al, 2020] ones. Geodetic studies, from permanent and campaign GNSS network measurements and InSAR, identified the deformation sources of the Aigion [1995] and Efpalio [2010] earthquakes, as well as slow aseismic shallow slip [Elias and Briole, 2018].…”

Section: The Corinth Rift Laboratory (Crl)mentioning

confidence: 99%

The Near Fault Observatory community in Europe: a new resource for faulting and hazard studies

Chiaraluce

Festa²,

Bernard³

et al. 2022

Annals of Geophysics

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The Near Fault Observatories (NFOs) community is one of the European Plate Observing System (EPOS, http://www.epos-eu.org) Thematic Communities, today consisting of six research infrastructures that operate in regions characterised by high seismic hazard originating from different tectonic regimes. Earthquakes respond to complex natural systems whose mechanical properties evolve over time. Thus, in order to understand the multi-scale, physical/chemical processes responsible for the faulting that earthquakes occur on, it is required to consider phenomena that intersect different research fields, i.e., to put in place multidisciplinary monitoring. Hence, NFOs are grounded on modern and multidisciplinary infrastructures, collecting near fault high resolution raw data that allows generation of innovative scientific products. The NFOs usually complement regional backbone networks with a higher density distribution of seismic, geodetic, geochemical and other geophysical sensors, at surface and sometimes below grade. These dense and modern networks of multi-parametric sensors are sited at and around active faults, where moderate to large earthquakes have occurred in the past and are expected in the future. They continuously monitor the underlying Earth instability processes over a broad time interval. Data collected at each NFO results in an exceptionally high degree of knowledge of the geometry and parameters characterizing the local geological faults and their deformation pattern. The novel data produced by the NFO community is aggregated in EPOS and is made available to a diverse set of stakeholders through the NFO Federated Specific Data Gateway (FRIDGE). In the broader domain of the Solid Earth sciences, NFOs meet the growing expectations of the learning and communication sectors by hosting a large variety of scientific information about earthquakes as a natural phenomenon and a societal issue. It represents the EPOS concept and objective of aggregating and harmonising the European research infrastructures capabilities to facilitate broader scientific opportunity. The NFOs are at the cutting edge of network monitoring. They conduct multidisciplinary experiments for testing multi-sensor stations, as well as realise robust and ultra-low latency, transmission systems that can routinely accommodate temporary monitoring densification. The effort to continuously upgrade the technological efficiency of monitoring systems positions the NFO at the centre of marketing opportunities for the European enterprises devoted to new sensor technology. The NFOs constitute ideal test beds for generating expertise on data integration, creating tools for the next generation of multidisciplinary research, routine data analysis and data visualization. In particular focus is often on near-real time tools and triggering alarms at different levels are tested and implemented, strengthening the cooperation with the Agencies for risk management. NFOs have developed innovative operational actions such as the Testing Centre for Earthquake Early Warning and Source Characterisation (CREW) and detailed fast ground shaking and damage characterization. Complementing the recent growth of modern laboratory and computational models, the NFOs can provide interdisciplinary observations of comparable high resolution to describe the behaviour of fault slip over a vast range of spatial and temporal scales and aiding to provide more accurate earthquake hazard characterizations.

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Spatiotemporal Properties of Seismicity and Variations of Shear-Wave Splitting Parameters in the Western Gulf of Corinth (Greece)

Cited by 9 publications

References 83 publications

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

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

Identification and Temporal Characteristics of Earthquake Clusters in Selected Areas in Greece

The Near Fault Observatory community in Europe: a new resource for faulting and hazard studies

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