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Peninsular India (10.0Њ N-28.0Њ N; 68.0Њ E-90.0Њ E) is one of the oldest and seismically most stable landmasses of the Indian plate. Recent seismic history, however, shows that more than five damaging earthquakes with magnitudes greater than M w 6.0 have occurred in this region, highlighting the importance of seismichazard assessment for the region. This article estimates the probabilistic seismic hazard associated with peninsular India with a zoneless approach incorporating the observed seismic activity and known geological characteristics of the region. The seismicity parameters for hazard assessment have been estimated incorporating completeness criteria for various spans of the catalog data. The spatial and temporal variations of seismic activity have been modeled using different source models. Seismic source zones for the region have been defined on the basis of large-scale geological features, which are used for assigning the maximum possible earthquake potential. Due to the poorly known attenuation characteristics of the study region, three appropriate attenuation models have been used for the estimation of groundmotion parameters. Hazard maps for peninsular India have been developed using a convolution scheme based on weighting and incorporating various uncertainties involved while modeling different parameters. The comparison of the probabilistic seismic-hazard map developed herein with the hazard map specified in the Indian Standards shows that the design parameters in the Indian Standards may significantly underestimate the seismic hazard in some regions of peninsular India.

SUMMARYTwo mode combination methods are presented for structures with non-classical (non-proportional) damping. They are of the same level of complexity as the well-known SRSS and CQC methods. They require only a single, real-valued participation factor for each mode, a single correlation coefficient, and standard relative displacement response spectra.A base-isolation study shows that the standard SRSS and CQC methods for classically damped structures give under-conservative response predictions, and that the proposed methods give accurate predictions.

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We review the definitions, population trends, and characteristics of megacities. Characteristics of megacities are, apart from their size, their complexity in terms of administration, infrastructure, traffic, etc., and at the same time the speed of change. Vulnerabilities and risk potential are discussed using the examples of Mexico City and Mumbai. We present the experience accumulated in the 6 years work of the Earthquakes and Megacities Initiative (EMI, http://www-megacities. physik.uni-karlsruhe.de/) with more than 20 large cities around the world, mostly located in the developing world. On this background we analyze obstacles that keep megacities from developing an efficient approach towards disaster mitigation and define a strategy that might overcome these problems. The key element of this strategy is the development of a Disaster Risk Management Master Plan (DRMMP) for cities. Currently the Istanbul Earthquake Master Plan (IEMP) serves as best example for an appropriate strategy for disaster reduction in megacities.Keywords Megacity AE Urbanization AE Vulnerability AE Disaster mitigation AE Risk management master plan Trends in urbanizationThe world has experienced rapid urbanization during the past few decades. While in the 1950s approximately 18% of the world's population was living in urban areas, this