PRELIMINARY STUDY FOR EVALUATION OF EARTHQUAKE RISKTO THE HISTORICAL STRUCTURES IN KATHMANDU VALLEY(NEPAL)

摘要

In this study, an attempt to assess the seismic vulnerability of the historical infrastructures like templesand stupas of Kathmandu valley, Nepal was carried out. The estimation of periods of multi-tiered templeswas done by using empirical equations. To estimate the periods of soil, theoretical transfer function of SHwaves was used. It is found that there may not be severe impact to the temples located at the valley floorduring far field earthquakes due to difference in predominant period of temples, stupas and the ground.However, temples and stupas which have experienced some past earthquake motions could exhibit longernatural period due to existing cracks. In such cases, there are possibilities of resonance effect because theperiod of temples and stupas are closer to the predominant period of the ground. Likewise, the templeslocated at the border of the Kathmandu Valley may have severe damage from resonance effect due to theshort periods of temples and sites near rock outcrops. It is observed that most of the important templeslike Pashupatinath, Nyatpol, Gujeshwori, Krishna Mandir, Banglamukhi and stupa like Boudhnath aresituated over geological formations which may be at risk of liquefaction under sever seismic impact.These results are from the preliminary phase of analysis, and detailed field measurements such as theperiods of structures, soil and various sub-surface structures are necessary for the further investigation.