UCLA

The research presented in this thesis was directed toward improvement of the shear wave velocity profile database (VSPDB) in two principal respects and its application for sites in Utah. The first improvement of the VSPDB was related to quality assurance checks of information that has been uploaded to the database since about 2016. A tool was created in python to plot profiles and each of 4225 profiles were visually examined to identify errors. These errors include zero velocity values, depth errors, and incorrect data formatting. In many cases, potential errors could only be confirmed or corrected by reviewing source documents. Following these reviews, profiles for 621 sites were corrected (15%). The second improvement of the VSPDB involved replacing the original database structure, or schema, with a new version. The new schema includes a test table that allow multiple data types associated with a given test, such as a seismic cone penetration test, to be properly linked to each other. To implement the new schema, an entirely new version of the database was created. Data from the original database has been migrated to the new database, although this is not the case for all data fields. While all the VS fields have been migrated, additional work will be required to migrate other data types. The website to access the database (https://www.vspdb.org) will still access the old database until the remaining data types have been fully migrated. The VSPDB was supplemented with 259 profiles from 205 unique sites in Utah. This study region is of interest because ground motions from Utah are being considered in the NGA-West3 project, but prior to the present work, no information on site conditions was available in NGA databases. Three of the profiles were paired with Utah ground motion stations but 92 other stations lack a co-located profile. For this reason, a proxy-based model to predict the time-averaged velocity in the upper 30 m of the site (VS30) was developed that considers surface geology and surface gradient for Quaternary units in Utah. The available profile data did not allow the development of models for rock sites, for which VS30 was estimated using models for other regions.