Earthquake Source Properties of a Lower Crust Sequence and Associated Seismicity Perturbation in the SE Carpathians, Romania, Collisional Setting

Plăcintă, Anica Otilia; Borleanu, Felix; Popescu, Emilia; Rădulian, Mircea; Munteanu, Ioan

doi:10.3390/acoustics3020019

Cited by 5 publications

(1 citation statement)

References 64 publications

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“…We conclude that installation of new seismic sensor in around Opak Fault can decrease the Mc value. This result is consistent with previous research, which states that the decrease of Mc is directly related to to the seismic network improvements to monitor seismicity in the region [24,25]. The frequency magnitude distribution of both catalogs yields general b-value and a-value as well .…”

Section: Resultssupporting

confidence: 92%

Earthquake statistical performance due to increasing of the seismic network around Opak Fault, Yogyakarta

Fauzi Masykuri,

Setyo Yuliatmoko,

Dairoh

et al. 2023

E3S Web Conf.

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The seismic event in May 2006 underscored the critical necessity of continuous earthquake monitoring. Observational enhancement through adding more stations is very crucial to obtain a more refined data quality. From January 2009 to September 2019, BMKG PGR (Pusat Gempa Regional/Regional Earthquake Centre) VII documented approximately 1847 seismic events with magnitudes from 0.9 to 4.9. With the integration of additional seismic station into the array by December 2022, there was a notable increase of 1418 recorded events in the same magnitude interval. The earthquake observation average is increasing as well, from 15.4 events in a month to 20.5 events in a month. This study leverages this data to assess the impact of augmenting seismic stations proximal to the Opak Fault on seismicity parameters within that region. Employing ZMAP 6.0, a comparative analysis of seismicity parameters was conducted between the earthquake catalog from January 2009 to September 2019 and the expanded catalog from January 2009 to December 2022. Declustering process result 1790 and 3141 main earthquake events in each catalog. This research indicate that the inclusion of more stations significantly influences the Mc value and earthquake density, however, it does not have a significant effect on the b and a-value.

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Section: Resultssupporting

confidence: 92%

Earthquake statistical performance due to increasing of the seismic network around Opak Fault, Yogyakarta

Fauzi Masykuri,

Setyo Yuliatmoko,

Dairoh

et al. 2023

E3S Web Conf.

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Seismic attenuation tomography of Eastern Europe from ambient seismic noise analysis

Borleanu,

Petrescu,

Placinta

et al. 2023

Geophysical Journal International

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Summary The Eastern-Europe region (EER), is a complex geotectonic area that captures part of the Alpine-Himalayan Orogen, the subduction of multiple NeoTethys Branches and part of the East European Craton. It is one of the most exciting geological areas in Europe due to a diversity of tectonic processes acting within it: extensional basin evolution, oceanic subduction, post-collisional volcanism, as well as active crustal deformation associated with the push of the Adria plate or the pull of the actively detaching Vrancea slab. This makes EER an excellent natural laboratory to study the behavior of the lithosphere-asthenosphere system in a heterogeneous tectonic setting. To investigate the lateral heterogeneity and physical properties of the crust in the EER, we use ambient seismic noise data recorded by the vertical components of broadband stations that have been operational between 1999 and 2020 in Eastern Europe and surrounding regions. We used this significant amount of data and the latest processing techniques of the ambient seismic noise field based on the continuous wavelet transform to compute cross-correlations between various station pairs, turning every available seismic station into a virtual source. The coda of the inter-station cross-correlograms were used to determine coda quality factors (Qc) of Rayleigh waves in four different period ranges (3.0–5.0s, 5.0–10.0s, 10.0–20.0s and 20.0–30.0s) and to invert them in the 2D space, constructing the highest resolution attenuation tomography of the region. Our results reveal high attenuation features throughout the north-east Pannonian region, the Bohemian Massif, the East Carpathians, and the Moesian Platform. Nevertheless, our findings do not emphasize a close correlation between the depth of sedimentary basins and attenuation features identified at longer periods. In addition, Qc variations are larger at short periods, indicating higher heterogeneity in the uppermost crust of Eastern Europe. Our findings demonstrate the higher efficiency of noise correlation approaches relative to earthquake data analyses investigating Qc at low frequencies.

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Past Earthquake Simulations Using Ambient Seismic Noise in Vrancea, Romania

Petrescu

Plăcintă

Borleanu

et al. 2023

Seismological Research Letters

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The Vrancea seismic zone (VSZ), located in Romania, at the sharp bend of the southeast Carpathians, is an anomalous intraplate seismic nest releasing the largest strain in continental Europe. The last powerful earthquake in Vrancea occurred in 1977 causing significant damage to the densely populated cities in southeast Romania. The seismic infrastructure was underdeveloped at that time and the earthquake was not well recorded locally. Using ambient seismic noise recorded at modern broadband seismic stations around Vrancea in the year 2020, and the approximate moment tensor solutions of significant earthquakes Mw>6 since 1977, we reconstruct ground-motion waveforms recorded by modern seismometers decades after their occurrence. The virtual earthquake approach uses empirical Green’s functions from ambient noise cross correlations between pairs of seismic stations and adds the signatures of a model earthquake: double couple mechanism, buried source, and a realistic earth model in the epicentral area. Ambient noise data capture the signatures of complex subsurface structures and the 3D path effects, providing a more physically accurate representation of the seismic wavefield than purely synthetic data. Our new results demonstrate the viability of this innovative method and provide a unique opportunity for more accurate seismic hazard analysis in intraplate seismic zones with insufficient instrumental data.

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Earthquake Source Properties of a Lower Crust Sequence and Associated Seismicity Perturbation in the SE Carpathians, Romania, Collisional Setting

Cited by 5 publications

References 64 publications

Earthquake statistical performance due to increasing of the seismic network around Opak Fault, Yogyakarta

Earthquake statistical performance due to increasing of the seismic network around Opak Fault, Yogyakarta

Seismic attenuation tomography of Eastern Europe from ambient seismic noise analysis

Past Earthquake Simulations Using Ambient Seismic Noise in Vrancea, Romania

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