پژوهشنامه زلزله شناسی و مهندسی زلزله
سال پانزدهم شماره 2 (پیاپی 56، تابستان 1391)

On the occasion of the 50th anniversary of the Buin-Zahra Earthquake of 1 September 1962, a case study on the seismicity of Qazvin plain in west Tehran area was performed, from which the results are presented herein. The methodology of the study is based on the field observation on the archeological sites and the macroseismic epicenters of the 20th century events in this region. In this article, it is tried to summarize the seismotectonic specifications of the Qazvin plain with an emphasis on the Buin-Zahra (1962) and Changureh (2002) earthquakes surface features. The probability of chain earthquakes in the western Tehran area is studied as well. The Estehard fault is located in the eastern end of the Ipak fault and the north Tehran fault is located in the eastern end of Eshtehard fault. This is important due to a seismic gap which exists in the western Tehran region. The population of Tehran and Karaj (in west Tehran) is an important factor due to seismic risk study in this active region.

The occurrence of 1962 Buin-Zahra and 2002 Avaj earthquakes are evidences of high seismicity of Qazvin province, Iran. In this regard, National Iranian Broadband Network pursues the aim of continuous monitoring of earthquake events all over the country. In this paper, the current capabilities and future development plans of this network have been presented. By completing the development of broadband network, all seismic events with magnitude greater than 2.0 will be recorded by the network. In continuation, the past seismicity of the Qazvin province, recorded by Iranian Broadband network, is analyzed and magnitude of completeness and the special pattern of seismic events have been presented.

It is obvious that foundations supporting vibrating equipments do experience elastic and elasto-plastic displacements. Consequently, the amplitude and frequency contents of the induced elastic vibrations should be eliminated to permissible limits. These limits are generally prescribed by the machine manufacturers. In fact, for some machinery foundations, the intensity of vibration may be objectionable for the equipment itself. In this condition, the operating vibrations should be controlled to prevent the resonance conditions in foundation-soil system. Besides, there are some environmental limitations in operating the high sensitive structures and equipments. In this case, the vibration may not be within a tolerable limit for sensitive equipment nearby. Consequently, the acceleration, velocity and displacement of the vibration should be eliminated to predefined values. In order to illustrate the above mentioned phenomenon, some guidelines for allowable vertical vibration amplitude for particular frequency of vibration will be presented in this paper. Finally, the test procedures, signal processing details and analysis results of two case studies in Iran will be explained. These cases which are located in Mahshahr and Qazvin have been studied in International Instit ute of Earthquake Engineering and Seismology.

This paper briefly discusses the effect of link beam’s eccentricity with respect to the inplane center line of coupled shear walls, on their behavior and capacity which is important for analysis and design. This investigation concen-trates on the nonlinear behavior of RC coupled shear walls which are selected from an eight story building having structural seismic dual system. This building was analyzed and designed according to the Iranian code of practice for seismic design (IS-2800), utilizing ETABS software and ACI-318 code of practice. Coupled shear wall was modeled according to the ABAQUS computing program with various ratio of eccentricity. Nonlinear static and dynamic analysis of this model is carried out for various ratios of eccentricities. A total of three earthquake records (Bam Eq., Roudbar Eq. and Tabas Eq.) were used in nonlinear dynamic analysis. Results indicate that due to the eccentricity of link beam, the out of plane bending moment, out of plane shear force exerted to the shear wall increase by increasing the eccentricity ratios; and the variation of their maximum values corresponding to the eccentricity ratios have regular pattern. On the other hand, the inplane shear force for all models decreases about 20 to 30 percent. The out of plane displacement of shear walls were considerably ignorable.

On September 1, 1962 a strong earthquake (Ms = 7.2) occurred in Qazvin Province, North-Central parts of Iran due to movement of Ipak Fault which affected a large part of the country. Its epicenter was located in Buin-Zahra region which resulted in complete destruction of the town and all the surrounding villages including Danisfahan, Takestan, Tofak, Rudak, Sagiz-Abad, Roostam-Abad, Aghche-Mazar and Ipak. It was also felt in Tehran and almost all other main cities around the epicenter. In this paper, at first the characteristics of the affected areas and the impacts of the event will be presented briefly and the challenges observed in disaster management, focusing on emergency response activities, will be explained. Then, comparing the impacts of the event with other earthquakes that occurred afterward, the shortages of disaster management system of the country will be discussed and some suggestions are presented to improve the existing conditions.

On Saturday night of 1st September 1962 (10 Shahrivar 1341), an earthquake with a magnitude of 7.2 Ms occurred in the west zone of Tehran and south of Qazvin which claimed 12,225 lives. This region has experienced major earthquakes throughout history with massive human casualties. This earthquake influenced government and administrative infrastructure. This paper includes a descriptive and library research using literature review and documents. On the basis of official documents related to 1962 that were extracted from the National Archive of Islamic Republic of Iran and the Documentation Center of the Diplomatic History of the Ministry of Foreign Affairs about Buin-Zahra earthquake, various aspects of this event were revealed. With a glance on the last 50 years related documents of this earthquake, they reflect information process, crisis management, internal and foreign assistance. The paper describes various aspects of this earthquake which can be considered as one of the major earthquakes in Iran history.