Attenuation Relations for Peak Horizontal and Vertical Accelerations of Earthquake Ground Motion in Iran: A Preliminary Analysis

Attenuation relations are developed based on information in the Iranian acceleration data bank (IADB) containing 279 entries from about 30 seismogenic areas across the country. The peak ground horizontal (PGH) and peak vertical accelerations (PGV), varies from a few cm/s2 to over 1000 cm/s2. Moment magnitudes (Mw) vary from about 3.0 to 7.4; and earthquake depths vary from near surface to over 100 km; however, except a majority of depth that are kept at 33 km in the locating process, most depths are about 10 km. Epicentral distances (EPD) vary from 2 km to nearly 250 km. The data bank also includes four site conditions, S. The least squared multi-stage regression solutions for acceleration attenuation are calculated for three cases. The predicted PGH and PGV accelerations are compared with uncorrected high accelerations components near the source of Bam earthquake of 2003; the high PGH acceleration is reproduced, but the estimated PGV acceleration is lower by a factor of 2 to 3. In addition, estimations based in this work are compared with several other studies and discrepancies are discussed.