[S02-P] Poster

[S02-P-13] Spectral Characteristics of the 2006 Quarry Blasts in the Tehran Region based on the TDMMO Network

^○Jamileh Vasheghani Farahani¹, Hiroe Miyake² (1.Institute of Geophysics, University of Tehran, Tehran, Iran, 2.The University of Tokyo, Tokyo, Japan)

Tehran, the capital city of Iran, is located between the Alborz and Central Iranian tectonic zones. The Tehran region has several active mines in the south and southeast of Tehran. They produce quarry blasts with small magnitudes. In this research, spectral characteristics were computed for data from the Tehran Disaster Mitigation and Management Organization (TDMMO) network in the Tehran region. Data catalog was selected from previous studies from discrimination between microearthquakes and quarry blasts in 2012 by adaptive neuro-fuzzy inference systems method. Data was selected and analyzed for one year duration from Jan to Dec 2006. A total of 42 events quarry blasts data was extracted from the quarry blast catalog. The Brune's model is used to estimate source parameters like corner frequency and fmax. We obtained spectral characteristics for stations with a criterion for the signal to noise ratio; where signal to noise ratio was larger than 2. Magnitude (Mw) for the quarry blasts was calculated from 1.1 to 2.4 at epicentral distances between 8.81 and 43.90 km. Mean of moment magnitude for all signals and stations from 42 events has been evaluated to be Mw=1.6, and also mean of seismic moment obtained; M0 =4.4E+11 Nm. Maximum and minimum seismic moment for events are calculated to be 3.80E+12 and 5.10E+10 Nm, respectively. Other parameters like mean of corner frequency and fmax for this research for all signals obtained 1.7 and 4.8 Hz, respectively. Moreover, the average stress drop by the quarry blasts in the Tehran region obtained about 2.4 MPa. Comparison between the previous studies for a crustal earthquake in the Tehran region in 2009 and this study showed that stress drop for quarry blasts (2.4 MPa) are a bit smaller than the crustal earthquake (3.3 MPa). Results for this research can be used for both seismological and engineering purposes.