SPATIAL AND TEMPORAL VARIATION OF SEISMICITY IN BULGARIA BASED ON THE EARTHQUAKE CATALOG (1981–2019)

Emil Oynakov, Irena Aleksandrova, Maria Popova

Abstract:
This study statistically analyzed the earthquake catalogue for the period 1981– 2019, (Solakov et al., 2020). The catalogue consists of earthquakes localized on the territory of Bulgaria and its surroundings area (410 – 44.60N, 220 – 300E; 1024 events). The present data from the earthquake catalogue have been studied in two aspects – temporal variation and spatial distribution. For the region, original data were used without modification; were calculated: b-values, a-values, magnitude of completeness (Mc). A focal depth h = 0–60 km was chosen to calculate the b-values. Results obtained from a catalogue with dependent events present have no statistical significance. For this, dependent events were removed using the proposed declustering technique in the Zmap software (Wiemer and Wyss, 2000). Magnitude completeness Mc was calculated using the maximum curvature method (Wiemer and Wyss, 2000). The residual catalogue obtained after declustering, including 625 events with Mw ≥ 3.2, is used to estimate various parameters characterizing the temporal and spatial seismic activity in the spatial extent of the catalogue (b-value, a-value, etc.)

Keywords:
Catalogue, declusterization, b-value, magnitude completeness (Mc)

Problems of Geography, 2023, Vol.1-2, DOI: 10.35101/prg-2023.1-2.2

Author information:
Author: Emil Oynakov
E-mail: emil.ilievmg@gmail.com
Affiliation: National Institute of Geophysics, Geodesy and Geography – BAS, department of Geography, str. Acad. G. Bonchev, bl. 3, Sofia 1113, Bulgaria

Author: Irena Aleksandrova
E-mail: i.alex@abv.bg
Affiliation: National Institute of Geophysics, Geodesy and Geography – BAS, department of Geography, str. Acad. G. Bonchev, bl. 3, Sofia 1113, Bulgaria

Author: Maria Popova
E-mail: m.popova022@gmail.com
Affiliation: National Institute of Geophysics, Geodesy and Geography – BAS, department of Geography, str. Acad. G. Bonchev, bl. 3, Sofia 1113, Bulgaria

How to cite:
Oynakov, E., Aleksandrova, I., & Popova, M. (2023). Пространствена и времева вариация на сеизмичността в България на основа Каталога на земетресенията (1981-2019). Problems of Geography, 2023, Vol.1-2, p. 15-29. https://doi.org/10.35101/PRG-2023.1-2.2