Los Angeles faces the constant threat of a major earthquake, but new research offers a glimmer of hope. A simulation of a magnitude 7.8 earthquake on the south San Andreas fault suggests that the city might experience 50% less ground motion than previously anticipated. This could be a significant positive for Los Angeles, but experts caution that this is just one scenario and more research is needed to fully understand the potential impact of a large earthquake.
The study, which is yet to undergo peer review, updates computer modeling conducted during the 2008 Great Southern California ShakeOut. This project aimed to assess the consequences of a major earthquake on the San Andreas fault, which runs close to downtown Los Angeles. The ShakeOut predicted significant ground motion in downtown Los Angeles, leading researchers to question the accuracy of those simulations.
The previous simulations suggested that the basins surrounding the city, like the San Gabriel basin and the Los Angeles basin, would act as waveguides, funneling earthquake waves towards the city. However, the new study, using more detailed models and actual topography, suggests that the mountainous terrain around the fault has a scattering effect, reducing the intensity of earthquake waves entering the basins.
While the findings are encouraging, researchers emphasize that they are still far from a complete understanding of the potential impact of a major earthquake. More data from actual earthquakes is needed to refine these models and provide more accurate predictions. Additionally, the ground motion can vary greatly within Los Angeles, with areas near mountains experiencing more rigid ground and areas in the middle of the Los Angeles basin experiencing more loose sediment.
The presence of other fault networks near Los Angeles further complicates the picture. This study represents a significant step forward in understanding earthquake risks in Los Angeles, but it highlights the complexity of the problem and the need for continued research and data collection.
