Seismic Waveform Data from Greece and Cyprus: Integration, Archival, and Open Access

Abstract

The National Observatory of Athens data center for the European Integrated Data Archive (EIDA@NOA) is the national and regional node that supports International Federation of Digital Seismograph Networks and related webservices for seismic waveform data coming from the southeastern Mediterranean and the Balkans. At present, it serves data from eight permanent broadband and strong-motion networks from Greece and Cyprus, individual stations from the Balkans, temporary networks and aftershock deployments, and earthquake engineering experimental facilities. EIDA@NOA provides open and unlimited access from redundant node end points, intended mainly for research purposes (see Data and Resources). Analysis and quality control of the complete seismic data archive is performed initially by calculating waveform metrics and data availability. Seismic ambient noise metrics are estimated based on power spectral densities, and an assessment of each station’s statistical mode is achieved within each network and across networks. Moreover, the minimum ambient noise level expected for strong-motion installations is defined. Sensor orientation is estimated using surface-wave polarization methods to detect stations with misalignment on particular epochs. A single data center that hosts the complete seismic data archives with their respective metadata from networks covering similar geographical areas allows coordination between network operators and facilitates the adhesion to widely used best practices regarding station installation, data curation, and metadata definition. The overall achievement is harmonization among all contributing networks and a wider usage of all data archives, ultimately strengthening seismological research efforts in the region.

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

“…The primary data used in this study are the recordings of the seismological stations of the CRL network and of the local stations of the Hellenic Unified Seismological Network (HUSN). These were acquired through the web services of the international Federation of Digital Seismograph Networks (FDSN); specifically, from the Réseau sismologique et géodésique français (RESIF; http://seismology.resif.fr/) (accessed on 9 July 2021), for stations of the CRL network, and from the National Observatory of Athens data center for the European Integrated Data Archive (EIDA@NOA; http://eida.gein.noa.gr/) (accessed on 9 July 2021), for stations of the HUSN [31]. In the following subsections, we present the various methodologies that were followed to process the available data and produce the results which are further described in Section 3.…”

Seismicity Patterns Prior to the Thessaly (Mw6.3) Strong Earthquake on 3 March 2021 in Terms of Multiresolution Wavelets and Natural Time Analysis

“…The goal of the present work is to test and evaluate the seismicity patterns in terms of MRWA and NT analyses, as applied in the evolution of seismicity prior to the recent Mw6.3 Thessaly strong event. The recent upgrading of the regional seismological networks [48] provides an accurate catalogue of microseismicity in the area and enables the The concept of natural time (NT) has been introduced recently to analyze possible pre-seismic signals [29,30,35]. The analysis of various complex systems in the NT domain enables the optimal extraction of signal information by reducing the uncertainties related to the conventional time, as well as the identification of long-range correlations in the evolution of the system, even in the presence of "heavy tails" [40].…”

“…The goal of the present work is to test and evaluate the seismicity patterns in terms of MRWA and NT analyses, as applied in the evolution of seismicity prior to the recent M w 6.3 Thessaly strong event. The recent upgrading of the regional seismological networks [48] provides an accurate catalogue of microseismicity in the area and enables the application of such methodologies. The earthquake catalogs used herein are taken from the Hellenic Unified Seismological Network (HUSN) (http://eida.gein.noa.gr/, last accessed on 27 May 2021), where instruments belonging to the HL (National Observatory of Athens, Institute of Geodynamics, 1997) [49] and HT (Aristotle University of Thessaloniki Seismological Network, 1981) [50] networks provide a complete spatial coverage in the broader area of Greece, with a magnitude of completeness (Mc) down to 2.0.…”

The Evolution of Preseismic Patterns Related to the Central Crete (Mw6.0) Strong Earthquake on 27 September 2021 Revealed by Multiresolution Wavelets and Natural Time Analysis

“…The upgrading of the regional seismological networks [46][47][48][49][50][51] provides complete spatial coverage in the broader area of Greece and an accurate catalog of microseismicity, with a magnitude of completeness (Mc) down to 2.0, in the studied area (see Figure 3 in [51]), enabling the application of such methodologies. The earthquake catalogs used herein are from the revised solutions reported by the Hellenic Unified Seismological Network [52].…”