Geographic coverage: The report focuses on the Lower Hutt and Porirua areas within the Wellington Region, New Zealand. 

This report presents a detailed assessment of ground shaking hazards in the Lower Hutt and Porirua areas, prepared as part of the Wellington Regional Council’s Natural Disaster Reduction Plan. It identifies zones with varying levels of expected seismic shaking based on geological composition, seismic recordings, and numerical modeling. The study defines four hazard zones in Lower Hutt and three in Porirua, graded from Zone 1 (least shaking) to Zone 5 (most shaking). Zone 5 areas are typically underlain by soft, flexible sediments that amplify seismic waves, while Zone 1 areas are bedrock or firm ground with minimal amplification. 
 
Two earthquake scenarios are considered: Scenario 1 involves a large, distant earthquake producing moderate shaking on bedrock, and Scenario 2 involves a major local earthquake along the Wellington Fault. The report quantifies expected ground motion parameters such as Modified Mercalli Intensity (MMI), peak ground acceleration, duration of shaking, and frequency amplification. For Scenario 1, Zone 5 areas may experience MMI VIII-IX (8-9), while Zone 1 areas may experience MMI V-VI (5-6). Scenario 2 predicts more intense shaking across all zones, with Zone 5 potentially reaching MMI X-XI (10-11). 
 
The report emphasizes the importance of local geology in influencing earthquake damage and recommends further site-specific studies to refine hazard boundaries. It also highlights implications for infrastructure planning, noting that repair costs increase significantly with higher MMI levels. The findings support informed decision-making for land use and emergency preparedness in the Wellington Region.