Almenn verkefni 2024

Heiti verkefnis : 

Nýtt eðlisfræðilegt mat á jarðskjálftavárlíkindum á Tjörnesbrotabelti Norðurlands

Verkefnastjóri : 


Stutt lýsing á verkefninu:


The Tjornes fracture zone (TFZ) in North Iceland has been the primary source of historically destructive earthquakes. The TFZ connects the active tectonic extension of the Mid-Atlantic Ridge offshore north of Central Iceland to the active tectonic extension in the Northern Volcanic Zone on land in northeast Iceland. Therefore, the earthquake hazard is high in the TFZ and performing a probabilistic seismic hazard assessment (PSHA) is vital for seismic risk mitigation and management. For a reliable PSHA, the state-of-the-art specification of its three key elements is required: (1) seismic source models, (2) seismic activity rates denoted by a magnitude frequency distribution (MFD), and (3) ground motion models (GMMs) that describe the ground-shaking parameter as a set of predictive variables such as magnitude, distance, and site effects. During the past years, intense efforts have been undertaken in hazard research in Iceland to address all the fundamental elements required for a reliable PSHA. Most notably, a new physics-based 3D fault system model has been produced for the unique bookshelf fault systems in South and North Iceland. The 3D fault system model is calibrated to the rate of tectonic plate motions across the transform zone, subdivides the zone based on the systematic spatial variation in maximum expected magnitudes and fault slip rates. Moreover, the new model allows the derivation of simple but self-consistent MFDs that is fully consistent with the latest and most reliable revision of the Icelandic historical catalogue. Furthermore, a new set of empirical GMMs at all frequencies of engineering interest (0.2-20 Hz) are calibrated using Icelandic data and informative priors for the physics-based saturation of near-fault peak motions at larger magnitudes. Therefore, considering the aforementioned developments, it is evident that a comprehensive revision of the physics-based PSHA for the TFZ is required.

Tilgangur og markmið:


The long-term goal of this project is to mitigate the devastating effects of future earthquakes in TFZ, North Iceland. For this purpose, a comprehensive PSHA will be conducted based on a new and complete physics-based earthquake source model, finite-fault earthquake catalogues and a novel backbone approach. Therefore, the short-term goals of this specific proposal are the following distinct research topics that will be produced at the end of the project: (1) Simulating physics-based finite-fault earthquake catalogues that are consistent with the latest and most reliable revision of the Icelandic historical catalogue (i.e., ICEL-NMAR); (2) evaluating different GMMs for Peak Ground Acceleration (PGA) and Pseudo-Spectral Acceleration (PSA) against Icelandic earthquake data and selecting the best GMM as the backbone model; (3) Presenting seismic hazard maps for the TFZ for different hazard levels (4) Presenting disaggregation maps to identify hazard-dominating events; (5) Comparing the results of this study with past PSHA results (i.e., European hazard modes and the Icelandic National Annex for Eurocode 8).