Recent 2017-2018 Seismicity and News Seismic Hazard Zoning of Iran

On November 12, 2017, at 18:18 UTC, a major earthquake with moment magnitude Mw7.3 struck the Kermanshah province of Iran, causing extended damage and casualties. Thus, we explore seismicity preceding this earthquake, with the aim to understand whether the information from past events could provide some insights about the occurrence of this and other future large earthquakes. Taking into account the seism tectonic framework and high seismicity with destructive earthquakes as well as the large population density settled in the earthquake-prone areas, the necessity for the development of a database with field investigations for the seismic hazard and risk assessment is critical. It showed be noted that reliable seismic hazard studies depend on having a robust earthquake catalog, good knowledge of tectonic conditions and relevant attenuation model applied for the hazard analysis. The better input for hazard analysis results in more reliable the parameters and the seismic hazard assessments. The uncertainties associated with the seismic hazard analysis and level of success of the methodology in the region is also treated. In this regard, subjects such as data acquisition in earthquake recognitions, analysis of recorded strong motions, determination of physical damages, near-field effects like directivity and fling-step, and the importance of these analysis in hazard zoning are presented. After some earthquakes (such as the 2017 Mw7.3 Ezgeleh, Sare Pol Zahab, 1978 Mw7.4 Tabas earthquake, 1990 Mw7.3 Majil earthquake and 2003 Mw6.5 Bam earthquake), several questions were raised on the reliability of the seismic hazard zoning maps (e.g. Fig 1) and on the comparison between the recorded and previously assessed ground motions. This error originates from many parameters such as lack of enough data and a good knowledge about physics of complex earthquakes as well as inappropriate assumptions and models. Therefore, it is essential to revise maps permanently and to move forward in re-evaluation of seismic hazard algorithms and models. The construction of highways and urban developments has increased the potential areas for slop instabilities specially in mountainous areas. Such areas might be observed around Tehran, Tabriz, and along the major highways such as Hazard and Chalous across the Alborz Mountain belt. In active mountain ranges, landslides are important erosion processes. In tectonically active regions, the created uplift along with existed joints and faults can provide critical conditions for occurring landslides. On the other hand, earthquakes that are the aftermath of active tectonics can also trigger giant landslides. Giant landslides usually are of high volumes up to tens of km3,  the different samples of which have been reported in the world.