Akademik Veri Yönetim Sistemi
LATİN AMERİKA 8. ULUSLARARASI BİLİMSEL ARAŞTIRMALAR KONGRESİ, Habana, Küba, 1 - 05 Mayıs 2024, ss.105-114
In this study, by
achieving the regional and temporal analyses of earthquake occurrences in the
Lake Van and its surroundings, the seismicity rate changes at the beginning of
20224 were tried to reveal. For this purpose, evaluations for the future
earthquake hazard were made by considering the relationships between
seismotectonic variables such as b-value
which defines the magnitude-frequency relation of earthquakes, return periods,
occurrence probabilities and Z-value
describing seismic quiescence. Due to the large/destructive 2011 Van (Mw=7.2),
2012 Karagündüz-Van (Mw=5.0), 2021 Lake Van (Mw=5.0) and 2022 Muradiye-Van (Mw=5.3)
earthquakes in which occurred recent years, seismicity studies in this region
has become very important. For the regional and temporal analyses, in about
60-year period between 1964 and 2024, a data set including 24,774 earthquakes
with magnitudes ranging as 1.0£Mw£7.2 within the boundaries of
longitudes 42.0°E-44.0°E and 38.0°N-39.5°N was used. However, for seismic
quiescence analysis, a data set which was declustered by taking Mw≥2.5 and
including 4545 earthquakes was used. Completeness magnitude, Mc-value, was accepted as 2.5 and b-value was estimated as 1.03±0.08. This b-value
means that magnitude-frequency distribution of earthquakes in and around the
Lake Van is well represented by the accepted average value of b=1.0. Regionally, small b-values (<0.8), were observed in
Tendürek fault, Çaldıran fault, the north of Erciş fault, Yeniköşk fault,
around Van and Erçek Fault Zones, in the southeast of the Lake Van, around
Nemrut fault and in Gevaş and Tatvan. Occurrence probabilities of earthquakes
with magnitudes Mw=5.0, 6.0 and 7.0 in the intermediate (10 years) were
calculated as ~ 65%, ~ 10% and ~ 1%, respectively. Return periods of
the earthquakes with these magnitudes were estimated as ~ 10 years, ~ 100 years and ~ 1000 years, respectively. The regions where
seismic quiescence is observed at the beginning of 2024 include the areas
covering the Çaldıran and Erciş faults, just south of Saray fault, the vicinity
of Yeniköş and Van Fault Zones, the north of Gevaş and the vicinity of
Malazgirt fault. The regions where small b-value
and high Z-value were observed can be
considered as hazard areas in terms of future earthquake occurrences. Therefore,
describing earthquake characteristics by evaluating different seismotectonic variables
together will contribute to earthquake hazard studies in the
short/intermediate/long terms.