Ramezan Ramezani Omali, Mehdi Saeidian, Naser Hafezimoghadas,
Volume 9, Issue 1 (6-2015)
Abstract
Determination of Faults activity rate is among the most important parameters of evaluating faulting hazards. In this paper, active faults on region of Shahid Rajai dam of Sari with radius 100 km based on fractal dimension of faulting and earthquake as well as evaluation of slip rate were classified and those Activity rate were assessed. In order to determine of fractal dimension of faulting and earthquake, Box-counting method was used. For estimate of slip rate beginning the seismicity parameters (a&b) of study area was estimation. Then these parameters were normalized for each fault. Based on the existing relationships and having a&b for each fault, the seismic moment of fault was calculated. Finally according to extant relations for evaluation of seismic moment rate, slip rate of each fault was determined and the faults of study area were classified accordingly. By grading based on fractal dimensions, the faults of North- Alborz, Damghan and Garmsar have been the most active faults in the study area during the last 100 years and according to evaluations of active rate of faulting and earthquake based on fractal dimensions, generally set in category BD and their activity approved. The faults with very low slip rate and with long return period of earthquake, are possible causes of occurrence large earthquakes (856 AD) Gomes and inducement fault namely Damghan Fault is an example of these faults. The faults of Astaneh, Rameh and Cheshmeh-ali have been low slip rate and thereupon be able to develop high seismic moment rate. According to earthquake events in privacy of New faults introduced (Khorram-abad, Majid,…), the high activity rate of these faults seem logical
Dr. Ali Misaghi, Dr. Mohammd Raeesi,
Volume 19, Issue 4 (12-2024)
Abstract
In this comprehensive study, we investigate the spatial distribution of landslides, strong motion data, and seismic intensity patterns associated with the June 20, 1990, earthquake, which registered a moment magnitude (Mw) of 7.4. Our primary objective is to elucidate the rupture characteristics of this significant seismic event. A focal point of our analysis is the southeastern segment of the coseismic rupture zone. By integrating geological field observations with seismological data, we aim to determine the extent and nature of the rupture along this segment. Our findings indicate that the southeastern segment experienced only a partial rupture during the 1990 earthquake. This partial rupture is evidenced by the distribution and density of landslides, variations in ground motion recordings, and the observed intensity patterns. The incomplete rupture of this segment suggests that it retains a considerable amount of accumulated strain energy, which was not fully released during the 1990 event. Consequently, this segment remains a potential source for future seismic activity. The implications of these findings are significant for seismic hazard assessment and risk mitigation in the region. Understanding the rupture dynamics and the potential for future seismic events is crucial for developing effective preparedness and response strategies. Our study underscores the importance of continuous monitoring and detailed geological and seismological investigations to better anticipate and mitigate the impacts of future earthquakes.
