Ground-motion prediction for subduction-zone earthquakes : insights from South and Central American data

Models to predict the ground motion for earthquakes that occur in subduction zones are of great importance for earthquake risk reduction and mitigation in many parts of the world where there is a significant hazard from large earthquakes along the subduction interface and from earthquakes within the subducting slab. Most existing ground-motion predictive equations for subduction-zone events are primarily based on strong-motion recordings from Japan, Cascadia, Mexico, Alaska and New Zealand. In contrast, few records from South and Central America have been included in global predictive equations to date, although a major proportion of the seismicity of these regions is related to subduction-zone processes. The development of a strong-motion database from subduction-type events in South and Central America is therefore an important and essential step for ground-motion prediction in these regions as well as other subduction zones in the world. In this project two databases of strong-motion records from subduction-zone events along the Peruvian-Chilean and the Central American subduction zones have been developed. The Central American database compiled during this study consists of 554 triaxial ground-motion recordings from both interface and intraslab-type events of magnitudes between 5.0≤MW≤7.7. The database compiled for South America consists of 98 triaxial ground-motion recordings from 15 subduction-type events of magnitudes 6.3≤MW≤8.4, recorded at 55 different sites in Peru and Chile, between 1966 and 2007. These datasets have then been used to investigate the extent to which global and regional models for subduction regimes could be applied for the prediction of ground motions from the subduction events in these regions, following a maximum-likelihood approach. Regional differences in the ground-motion amplitudes amongst the South and Central America subduction zones are examined and preliminary adjustments to existing equations are made in order to resolve the differences between observed ground motions and predictions from these equations. This has led to suggestions for the prediction of ground motions from subductionzone earthquakes in the South and Central American regions.EThOS - Electronic Theses Online ServiceAlban programmeGBUnited Kingdo