Journal of Seismology and Earthquake Engineering
Year:2008 | Volume:10 | Issue:1|Papers Count:9

In this study, the teleseismic body waveform modeling of the far-field P- and SH-waveforms as well as spectral analysis of P-waves are used to determine the source parameters of March 14, 1998 Fandoqa earthquake (Ms 6.9). Its epicenter is located southeast of Iran at Kerman province on the Gowk fault system. Previous focal mechanism solutions indicate motion on right-lateral strike slip faults. Based on waveform modeling, the results of this study represent aright-lateral strike slip motion on a NW-SE striking fault with parameters: Fault plane (strike=158o, dip=54o and the rake of 200o) and auxiliary plane (strike=58o, dip=76o, rake=-35o), depth of 4km and seismic moment of 1.32E+19 N.m. The spectral analysis of the far-field P-wave pulses resulted in a fault length L ~20-26km, stress drop Ds ~23 bars and average displacement  ̄u ~ 1m. In this study, the variant models are also examined to determine the source dimension and it is found that both the Madariaga and Sato-Hirasawa models are more consistent with the surface faulting in this area.

Receiver function analysis in transition zone between the Zagros collision zone and the Makran subduction zone shows gradual increment of the Moho depth to ~58km into the north. The Moho depth is ~32km beneath western end of the Makran prism (58o E-26.6oN). Furthermore, crust thickening to ~58km is observed 60km west of the Zendan-Minab-Palami fault system (ZMP) that is unusual for this part of the Zagros. This implies deflection of the Arabian Platform west of the ZMP. The Moho upwarp under region of the Khurgu indicates that the mountain ranges were lifted enmasse as a result of crustal buckling under horizontal compression. Moho depth variation beneath other stations in eastern end of the Zagros is around ~45km and increases into north to~53km beneath Main Zagros Thrust (MZT). Strong PS conversion is observed under Zendan-Minab-Palami fault system in upper crust that could be related to unconsolidated material associated with this fault. Inversion of P travel time residuals suggests a low velocity zone beneath the transition zone in accordance with the receiver function result. This information implies under thrusting of the Arabian plate beneath the Central Iran and the gradual transition into thinner crust beneath the accretionary prism of the Makran.

Seismic performance of a symmetrical space frame structure resting on sliding bearing with restoring force device is studied considering all the six degrees of freedom. The sliding support is modeled as a fictitious spring with two horizontal degrees of freedom. In non-sliding phase the horizontal stiffness of sliding bearing is considered as very large whereas it is equal to zero during sliding phase. The El Centro, Turkey and Mexico earthquakes are adopted as the input motion. The response quantities obtained from the analysis are the acceleration, base shear, bending moment and displacement. In this study, the response of the isolated structure is compared with the response of the structure fixed at the base. Response of the isolation system with restoring force device is also compared with the response of the isolation system without restoring force device. In addition, the effects of coefficient of friction of sliding material, time period of the superstructure and the number of storeys on response of structure are also investigated. It is concluded from the study that the sliding bearing with restoring force device reduces the earthquake response of the structure. The restoring force device reduces the sliding and residual displacements without transmitting additional forces into the structure. Response of the isolated structure varies with the coefficient of friction of sliding material, time period of superstructure and number of storeys. Also, there exists an optimum coefficient of friction of sliding material for acceleration, base shear and bending moment at which acceleration, base shear and bending moment attains a minimum value.

In this article, the problem of determining pseudo dynamic pressure and its associated forces on a rigid vertical retaining wall is solved analytically using the horizontal slices method for both reinforced and unreinforced walls. The use of this method in conjunction with the suggested equations and unknowns offers a pseudo-dynamic method that is then compared with the results of an available software. In the proposed method, different seismic accelerations have been modeled at different soil structure heights. Reinforced soil pressure on a retaining wall and the angle of the critical failure wedge are calculated using the new formulation. It is shown that as the horizontal seismic acceleration coefficient increases the angle of the critical failure wedge is reduced and that the maximum extension force can be increased for each layer by using stronger and longer reinforcements. The results of the pseudo-dynamic method show that both vertical and horizontal seismic accelerations are essential coefficients for calculation of the required length and extension force of the reinforcements and that their importance increases as the vertical and horizontal seismic accelerations increase. Also, the location of the application point of the resultant pressure rises as the horizontal seismic acceleration coefficient increases.

Due to global warming large efforts have to be taken in order to find a CO2-free energy supply for private consumers as well as for industry. One of the so-called renewable energies is geothermal energy. A new geothermal power plant was built in Basel, Switzerland, in 2006. A few weeks after the first water injections a series of earthquakes occurred in the region, which seems to be connected with the pressing of water into the ground.