July 2026 Meeting of the Chapter

Modern seismic design leans on a single parameter — V_S30, the average shear-wave velocity in the upper 30 meters — to classify a site, pick its code coefficients, and predict how it will shake. ASCE 7-22 builds on this through site-class-based multi-period response spectra, which suffice for most sites. But a 30-meter average can’t always capture ground response governed by deeper structure. This talk climbs the ladder of site-effect evaluation using recent Hudson Geotechnics case studies: Menifee Valley Business Park (Chapter 21.2 ground motion hazard analysis), a Perris warehouse (Chapter 21.1 site response analysis), and Children’s Hospital Los Angeles (non-ergodic site response analysis with deep passive imaging to ~3,000 feet). The throughline is a question: when is V_S30 enough, and what justifies going beyond it? Attendees will leave with a framework for matching analysis complexity to the site — and a healthy skepticism toward the one number we ask to rule them all.

Kenneth (Ken) Hudson is a specialist in geology, strong ground motions, and engineering seismology. He obtained a BS in Earth Science with emphases in geology and geophysics in 2016 and a MS in geophysics in 2017 from the University of California, Santa Barbara. Dr. Hudson began working in industry in 2017 and then began attending courses at the University of California, Los Angeles simultaneously in 2018 where he obtained a MS and PhD in Geotechnical Engineering in 2020 and 2023, respectively.

As a licensed Professional Geologist in the state of California, Dr. Hudson has worked on geologic, geotechnical, and seismic design aspects for high-rise buildings, rail transportation systems, hospitals, schools, and other public and private facilities in the greater Los Angeles Area and internationally. Dr. Hudson has extensive geologic field experience and expertise in large scale computational and statistical analyses for application in geologic and geotechnical problems.