S U M M A R Y In general, seismic slip along faults reduces the average shear stress within earthquake source regions, but stress drops of specific earthquakes are observed to vary widely in size. To advance our understanding of variations in stress drop, we analysed source parameters of smallmagnitude events in the greater San Gorgonio area, southern California. In San Gorgonio, the regional t...

An earthquake of M, = 5.3 occurred at 32°58.7'N, 117°51.5'W southwest of Oceanside in San Diego County at 13:47 13 July 1986 (UT). This main shock was followed by an extensive aftershock sequence, with 55 events of ML > 3.0 during July 1986. The epicenters of the main shock and aftershocks are located at the northern end of the San Diego Trough-Bahia Soledad fault zone (SDT-BS) where it changes...

This paper presents structural evidence of extensional activity in Central Alborz during Mesozoic. The structural evidence of homogenous early stage stretching such as layer-parallel to oblique boudinage of Permian and Triassic rocks in various portions of the study area accompanied by extensional-fibrous fractures were followed with more advanced extensional features. These extensional structu...

The characteristics of near-fault ground motion are investigated considering heterogeneous slip distribution on the fault plane. Areas on the fault plane with large slip in compare with the average slip on the fault are known as asperity. The characteristics of strong ground motions in near-fault area are strongly affected by faulting parameters such as asperity location, maximum slip of asperi...

The transition from subduction to transform motion along horizontal terminations of trenches is associated with tearing the subducting slab and strike-slip tectonics in overriding plate. One prominent example northern Tonga zone, where abundant faulting NE Lau back-arc basin plate boundary asymmetric rollback. Here, we address fundamental question: how does this subduction-transform influence s...

This thesis investigates continental deformation at many different spatial and temporal scales and at several plate-tectonic settings. Our main purpose is to understand how the continental crust behaves under applied forces, both over geologic times and over shorter time scales such as the seismic cycle. The thesis consists of separate investigations of long-term and short-term plate boundary d...