Jonathan is an Emeritus at the Tucson office of the Geology, Minerals, Energy, and Geophysics Science Center. He received a PhD degree in geology from Stanford University in 1978. Since joining the USGS in 1977, he has performed a variety of applied- and basic-research investigations.
Among these, his research into the long-term history of the San Andreas Fault in southern California stands out.
Education and Certifications
Ph.D., Geology, Stanford University, 1978
M.S., Geology, University of California, Riverside, 1971
B.S., Geology, University of California, Riverside, 1969
Affiliations and Memberships*
San Bernardino National Forest
San Gorgonio Pass Water Agency
San Bernardino Valley Municipal Water Agency
U.S. Bureau of Land Management
Joshua Tree National Park,
San Bernardino County Geologist
Riverside County Geologist
Southern California Earthquake Center (SCEC)
Science and Products
San Andreas Fault System in Southern California
Hydrogeology and simulation of groundwater flow in the Lucerne Valley groundwater basin, California
Geology and hydrogeology of the Yucaipa groundwater subbasin, San Bernardino and Riverside Counties, California
Late Quaternary slip history of the Mill Creek strand of the San Andreas fault in San Gorgonio Pass, southern California: The role of a subsidiary left-lateral fault in strand switching
Basin thickness variations at the Junction of the Eastern California Shear Zone and the San Bernardino Mountains, California: How thick could the Pliocene sections be?
Evaluation of the Source and Transport of High Nitrate Concentrations in Ground Water, Warren Subbasin, California
Science and Products
- Science
San Andreas Fault System in Southern California
Southern California is home to nearly 24 million people and countless visitors who live, recreate, consume resources, and face the risk of natural hazards in the region. This project produces high-quality, multi-purpose geologic maps, databases, and reports that portray our understanding of the region’s four-dimensional geologic framework. We conduct stratigraphic, structural, geomorphological... - Publications
Hydrogeology and simulation of groundwater flow in the Lucerne Valley groundwater basin, California
The Lucerne Valley is in the southwestern part of the Mojave Desert and is about 75 miles northeast of Los Angeles, California. The Lucerne Valley groundwater basin encompasses about 230 square miles and is separated from the Upper Mojave Valley groundwater basin by splays of the Helendale Fault. Since its settlement, groundwater has been the primary source of water for agricultural, industrial, mGeology and hydrogeology of the Yucaipa groundwater subbasin, San Bernardino and Riverside Counties, California
The Yucaipa groundwater subbasin (referred to in this report as the Yucaipa subbasin) is located about 75 miles (mi) east of of Los Angeles and about 12 mi southeast of the City of San Bernardino. In the Yucaipa subbasin, as in much of southern California, limited annual rainfall and large water demands can strain existing water supplies; therefore, understanding local surface water and groundwateLate Quaternary slip history of the Mill Creek strand of the San Andreas fault in San Gorgonio Pass, southern California: The role of a subsidiary left-lateral fault in strand switching
The fault history of the Mill Creek strand of the San Andreas fault (SAF) in the San Gorgonio Pass region, along with the reconstructed geomorphology surrounding this fault strand, reveals the important role of the left-lateral Pinto Mountain fault in the regional fault strand switching. The Mill Creek strand has 7.1–8.7 km total slip. Following this displacement, the Pinto Mountain fault offset tBasin thickness variations at the Junction of the Eastern California Shear Zone and the San Bernardino Mountains, California: How thick could the Pliocene sections be?
We estimate the thickness of Neogene basin fill along the junction of the Eastern California Shear Zone and the North Frontal thrust system of the San Bernardino Mountains using gravity data with geologic and well log constraints. The geometry of the basin fill is of interest for groundwater assessment and location of potential faults, as well as providing an upper bound on the thickness of any poEvaluation of the Source and Transport of High Nitrate Concentrations in Ground Water, Warren Subbasin, California
Ground water historically has been the sole source of water supply for the Town of Yucca Valley in the Warren subbasin of the Morongo ground-water basin, California. An imbalance between ground-water recharge and pumpage caused ground-water levels in the subbasin to decline by as much as 300 feet from the late 1940s through 1994. In response, the local water district, Hi-Desert Water District, ins
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government