Evaluating Earthquake Impacts in Oslo, Norway: A Multi-Method Approach

Effectively presenting seismic risk results is crucial for ensuring that stakeholders, including policymakers and first-responders can understand and utilize the information for decision-making and risk mitigation. In this study, we conducted a comprehensive seismic risk assessment for Oslo (capital of Norway), integrating both deterministic and probabilistic approaches to capture a holistic view of potential earthquake impacts. Based on the field data from exposed major faults in the Oslo rift margin and historical earthquakes in this region, the deterministic analysis examined three scenarios using SELENA software: i) an Mw 5.4 earthquake that occurred in 1904 in the Oslo rift zone; ii) a hypothetical Mw 6.0 event on the east side of the rift zone, and iii) a hypothetical Mw 6.0 event along an exposed fault zone in the central rift zone. These scenarios were selected to reflect a few possible seismic events with varying likelihoods and severities. For both, deterministic and probabilistic approaches, one specific neighbourhood in the Oslo city region emerged as the most affected area due to its dense population and older building stock, highlighting the critical interplay between physical hazard and community-specific vulnerability. The combination of deterministic and probabilistic approaches offers a detailed and nuanced understanding of seismic risks in Oslo. The findings underscore the need for targeted mitigation efforts and preparedness strategies, particularly in neighbourhoods that are more susceptible to seismic risks. By integrating these comprehensive risk assessments, the study provides valuable insights into the uneven distribution of seismic risk across Oslo. The results aim to inform local authorities and policymakers, aiding in the development of effective strategies to enhance the resilience of the city's infrastructure and population against future seismic events.