Two earthquakes occurred on 11 August 2012 in East Azerbaijan province, NW Iran with Mw 6.3 at 12:23:15.9 and Mw 6.1;11 minutes after the first shock at 12:34:34.8 GMT time. In this study, we concentrated on the prope...Two earthquakes occurred on 11 August 2012 in East Azerbaijan province, NW Iran with Mw 6.3 at 12:23:15.9 and Mw 6.1;11 minutes after the first shock at 12:34:34.8 GMT time. In this study, we concentrated on the properties of the aftershock sequences in a duration of 7.5-month time-period data after the main shocks, recorded by Broadband Iranian Network (BIN). We obtained p, c and K parameters with the maximum likelihood method and the occurrence rate was modeled by the modified Omori formula. Besides, we showed that aftershocks of the aftershock in 7 Nov. 2012 (M = 5.6) also decay according to the modified Omori law. We investigated the spatial and temporal variations of b-values before and after the twin earthquakes with Mw 6.3 and Mw 6.1 approximately 20 km around North Tabriz Fault (NTF) in the region from 1996 to 2013 using Iranian Seismological Center (IRSC). We believed that a research of the past 17 years has clearly established that spatial b-value changes and seismicity rate are highly significant and meaningful. Moreover, our research led to a warning for a probable strong motion along NTF for the coming couple of years.展开更多
Seismic events are very complex spatial-temporal phenomena. Seismic catalogues, reporting information about spatial-temporal distribution of the main shocks, are nowadays available for many seismic areas in the world,...Seismic events are very complex spatial-temporal phenomena. Seismic catalogues, reporting information about spatial-temporal distribution of the main shocks, are nowadays available for many seismic areas in the world, very often major events mark the beginning of a series of earthquakes （aflershocks） whose frequency and energy are meanly decreasing in time down to the background level of activity. Azerbaijan is one of the most active segments of the Alpine-Himalayan seismic belt and marks the junction between the African-Arabian and Indian plate to the south, and Eurasian plate to the north. The cluster of earthquakes that struck near Varzeghan-Ahar was centered near the Gosha-Dagh fault, but preliminary data suggested that the fault was not responsible for the temblor. On the late afternoon of Saturday, August 11, 2012, the northwest of Iran was shaken by two of the strong earthquakes in Iranian history. First was hit by Mw （moment magnitude scale） = 6.4 Richter at local time 16：54 （12：23 GMT （Greenwich Mean Time））, and about 11 min later, an Mw = 6.3 struck 10 km to the west. The spatial-temporal clustering of micro earthquakes （aftershocks） near Varzeghan, is parameterized by means of a generalized passion model. The region has known faults but numerous smaller or deeply buried faults remain undated, according to the Geological Survey of Iran.展开更多
文摘Two earthquakes occurred on 11 August 2012 in East Azerbaijan province, NW Iran with Mw 6.3 at 12:23:15.9 and Mw 6.1;11 minutes after the first shock at 12:34:34.8 GMT time. In this study, we concentrated on the properties of the aftershock sequences in a duration of 7.5-month time-period data after the main shocks, recorded by Broadband Iranian Network (BIN). We obtained p, c and K parameters with the maximum likelihood method and the occurrence rate was modeled by the modified Omori formula. Besides, we showed that aftershocks of the aftershock in 7 Nov. 2012 (M = 5.6) also decay according to the modified Omori law. We investigated the spatial and temporal variations of b-values before and after the twin earthquakes with Mw 6.3 and Mw 6.1 approximately 20 km around North Tabriz Fault (NTF) in the region from 1996 to 2013 using Iranian Seismological Center (IRSC). We believed that a research of the past 17 years has clearly established that spatial b-value changes and seismicity rate are highly significant and meaningful. Moreover, our research led to a warning for a probable strong motion along NTF for the coming couple of years.
文摘Seismic events are very complex spatial-temporal phenomena. Seismic catalogues, reporting information about spatial-temporal distribution of the main shocks, are nowadays available for many seismic areas in the world, very often major events mark the beginning of a series of earthquakes （aflershocks） whose frequency and energy are meanly decreasing in time down to the background level of activity. Azerbaijan is one of the most active segments of the Alpine-Himalayan seismic belt and marks the junction between the African-Arabian and Indian plate to the south, and Eurasian plate to the north. The cluster of earthquakes that struck near Varzeghan-Ahar was centered near the Gosha-Dagh fault, but preliminary data suggested that the fault was not responsible for the temblor. On the late afternoon of Saturday, August 11, 2012, the northwest of Iran was shaken by two of the strong earthquakes in Iranian history. First was hit by Mw （moment magnitude scale） = 6.4 Richter at local time 16：54 （12：23 GMT （Greenwich Mean Time））, and about 11 min later, an Mw = 6.3 struck 10 km to the west. The spatial-temporal clustering of micro earthquakes （aftershocks） near Varzeghan, is parameterized by means of a generalized passion model. The region has known faults but numerous smaller or deeply buried faults remain undated, according to the Geological Survey of Iran.
