Justine Overacker, PhD
Justine Overacker is a Physical Scientist with the U.S. Geological Survey's California Water Science Center, working in the Groundwater Availability and Use program area.
Dr. Overacker specializes in creating techniques and models to assess groundwater availability and usage, with a focus on California's Central Valley. She utilizes geodetic measurements of land subsidence and near-surface geophysical methods to support her research.
Before joining the USGS, Dr. Overacker's research focused on vertical land motion and coseismic signals, leveraging data from the Nevada Geodetic Lab’s extensive network of over 20,000 Global Navigation Satellite System (GNSS) stations. She analyzed water mass removal in the High Plains aquifer by integrating GNSS, gravity satellite data, climate patterns, and groundwater information. Dr. Overacker also developed an automated approach to estimate earthquake displacements from GNSS time series. Additionally, she has experience working for a geodetic engineering startup and as a field geophysicist in industry, utilizing seismic and electromagnetic methods for oil and gas, mineral, and geothermal exploration.