This project includes an integrated research and education plan that incorporates local soil information into the regional evaluation of seismic hazards and expands visualization and analysis tools for the evaluation of three-dimensional geotechnical data. The project will focus on the regional evaluation and mapping of soil amplification and liquefaction. The research aim is to improve visualization and analysis tools that incorporate the overall variability as well as the spatial correlation of geotechnical data to improve regional evaluations of seismic hazards. More accurate, detailed maps of liquefaction and soil amplification susceptibility that account for inherent geologic variability will allow for an evaluation of the effect of this variability and therefore considerably improve the assessment of these seismic hazards over a regional scale. This in turn will allow communities to better plan and mitigate their effects on the built environment. This work will include the development of a three-dimensional visualization and analysis tool for mapping subsurface data and an extensive study of the effect of soil spatial variability on regional seismic hazards. The educational aim is both to encourage the next generation of engineers and scientists to work on seismic hazards and to educate all students about the cause of geologic hazards and associated risk so that they may be informed citizens. The educational component of the project will continue on-going initiatives in undergraduate education and expand into middle school education through the development and use of web-based GIS tools for seismic hazard and geotechnical education. The educational work involves partnerships between middle school teachers and undergraduates through summer research experiences and academic year outreach programs.
As part of this award, we investigated how to improve regional seismic hazard maps. Seismic hazard maps are developed for regions that are at risk for earthquakes. Seismic hazard maps can be developed to predict site amplification; a site amplification map will show spatial patterns of expected strong shaking if an earthquake were to occur. Seismic hazard maps can also be developed to predict liquefaction hazard. Liquefaction is a phenomena that occurs when an earthquake shakes the ground, and due to elevated pore pressures in saturated loose soil, the soil looses shear strength and can fail causing ground failure. In this NSF-sponsored effort, we developed improved methodologies for both site amplification and liquefaction hazard maps. An example site amplification map for Kobe, Japan is shown in the Figure 1. This map is developed using universal kriging (a geostatistical interpolation technique to combine a trend with point data where the trend in this case is related to the surficial geology map). We developed similar maps for liquefaction hazard for the Oakland, California. In the Oakland case study, we compard maps developed using different geotechnical data (standard penetration tests, cone penetration tests, and shear wave velocity measurements). We found that the map developed used shear wave velocity measurements best mapped the regional liquefcation pattern observed in the 1989 Loma Prieta earthquake. As part of this award, we also investigated using remotely sensed soil moisture and temperature data to identify liquefaction after an earthquake. Using this methodology, remotely sensed data can be used to quickly and efficiently map liquefied regions after an event. This could then be spot-verified by field visits. In parallel to the research activities, we worked with middle school earth science teachers to develop curriculum around geologic mapping, and local geology. We also developd a web-based interface that can be used to explore data related to geohazards and seismic hazard maps. The website uses Kobe, Japan and data related to the 1995 Hyogo-ken Nanbu earthquake to provide instructional materials and data about seismic hazards. The website can be found at gdc.cee.tufts.edu.
