Database of the Strong Ground Motion Near-Fault of Iran

Historical background attention to seismic events in the near-field ground motion goes back to the Parkfield (1966) and San Fernando (1971) earthquakes. In fact, the occurrence of earthquakes and the concentrated presence of population centers in earthquake- stricken areas have further clarified the destructive nature of seismic events in near-fault area for structural and earthquake engineers. Recognition and collection of recorded data from earthquakes in the near-fault area that have different effects can be effective in reducing damage to structures and can also be used in seismological studies and engineering research; therefore, forming a Database of  the near-field ground motions is necessary and vital. The most important effects of strong ground motion in the near-field are   long-period pulses due to the rupture directivity effect in the vicinity of the earthquake source, which appears   mainly in the direction perpendicular to the fault and in a short time, apply a lot of energy to the structure.In this study, the near-field records of Iranian earthquakes to evaluate the status of pulses long-period have been investigated. The studied seismic database includes 450 events of recorded earthquakes in Iran, which have been recorded and stored since the establishment of the Iran strong motion network until 2014.All of the selected earthquakes have characteristics of magnitude, epicentral distance, geological characteristics (soil type), location of accelerometer, date and time of event, focal depth, maximum ground surface acceleration, maximum ground surface velocity, and maximum ground surface displacement. It should be noted that the moment magnitude of all selected events is equal to a value between 5 and 7, and their epicentral distance is less than 30 km from the event location.Near-field records have been separated from other data due to their Forward Directivity and pulses long-period, and a total of 77 records of near-fault strong ground motion were identified with Forward Directivity.The selected data have the special characteristics of near-fault records that have pulses in the acceleration or velocity time history record, and their characteristics include a short period of strong ground motion, rupture directivity effects, and low-frequency pulses in velocity time history. The selected data in this study have the characteristics and values that have been mentioned, so it is possible that there are other data that have the characteristics of near-fault records and have long-period pulses in the earthquake record and at a distance of more than 30 km or outside from the moment magnitude range of 5-7.In general, the result of this research has led to the preparation of the database of the near-fault with the country's pulse-like records from the beginning of its establishment (in 1973 using the SMA1 analog accelerometer) until 2014 of the Iran strong motion network of the research center of the Ministry of Roads and Urban Development. The database collected in 60 stations (77 records) has provided comprehensive and reliable information about parameters such as moment magnitude, epicenter distance, focal depth, soil type, Predominant Period (Tp), Endurance Time. This database can be used as a reference to be used in projects, reports and researches of students at different levels of education, technical and engineering offices and companies, seismic hazard analysis studies, earthquake engineering projects and researches that require the use of near-field ground motion in Iran. The use of this refined database for the design of important structures in addition to the development of earthquake engineering knowledge is very important