Real-Time Mapping of PGA Distribution in Tehran Using TRRNet and peeqMap

Abstract

Tehran megacity, the political and economical capital of Iran with population of more than eight million residents, is situated in the seismically active zone of Alborz. The seismicity pattern of this zone shows occurrence of large earthquakes in long time periods (Masson et al. , 2005). Several large earthquakes such as the 855 A.D. M s 7.1, the 958 A.D. M s 7.7, and the 1117 A.D. M s 7.2 in the historical seismic catalog of Tehran and surrounding area proves that the city has a high level of seismic risk (Fig. 1). The last disastrous example among these earthquakes was in 1830, and the city is waiting for the next large earthquake (Ambraseys and Melville, 1982; Ashtari‐Jafari, 2010). Several active faults surround Tehran including North Tehran fault, Eyvanekey fault, North and South Ray faults (Fig. 1). Apart from existence of several active faults around the city, fast growth of population and urbanization in previous decades, and lack of strong regulations for urban development increased the vulnerability of Tehran to moderate to large earthquakes (Amini‐Hosseini et al. , 2009). Figure 1. Map showing major active faults (Hessami et al. , 2003), and seismicity around Tehran. Circles, epicenters of M s>6 earthquakes; numbers, the year of earthquake occurrence. The historical earthquakes are from Ambraseys and Melville (1982). Star, the epicenter of the 17 October 2009 ( M w 4.0). NRF and SRF in the dashed square area, closely surrounding the city, refer to South Ray fault and North Ray fault, respectively. Topographic contours at 200 m intervals of the boxed area are shown in Figure 3. Mindful of the seismic risk faced by the city, the Tehran Rapid Response Network (TRRNet) has been installed in the Tehran metropolitan area …