Liquefaction potential index calculations at cone penetration test sites in California

This data release provides tabulated liquefaction potential index (LPI) values for a standard set of earthquake magnitudes (M) in the range 4.5-9, peak ground accelerations (PGA) in the range 0-1.0 g, and groundwater depths (GWD) in the range 0-15 m, as described in detail in Engler and others (2025). We use these data to rapidly interpolate LPI values for any M-PGA-GWD combination. The LPI results are computed at 1781 cone penetration test (CPT) sites in California (Holzer and others, 2010). Additionally, the CPT sites are classified using surface geology maps (Wentworth and others, 2023; Wills and others, 2015; Witter and others, 2006).

cpt_locations.csv
This file has one CPT site per row and includes the site’s coordinates and surface geology classes. 

cpt_lpi_table.csv
This file contains LPI results for each site across the range of M, PGA, and GWD values described in Engler et al. (2025). The LPI calculation details are given in the section titled “Liquefaction Potential Index,” and the LPI equation is given in Equation 1.

Each of these files has a column "CPTSite." This is an index that is used to relate the data in the two different files. 

In addition there is a README.txt file that also describes the contents of the files included in this data release.

References 
Engler, D.T., Thompson, E.M., Maurer, B.W., Geyin, M., Bürgi, P.M., Allstadt, K.E. and Jaiswal, K.S., 2025, Updating Regional-scale Geospatial Liquefaction Models with Locally Available Geotechnical Data: Seismological Research Letters, accepted. 

Holzer, T. L., 2010, Maps and documentation of seismic CPT soundings in the Central, Eastern, and Western United States: U.S. Geological Survey Open-File Report 2010-1136, 10 pp., https://doi.org/10.3133/ofr20101136.

Wentworth, C.M., Knudsen, K.L., and Witter, R.C., 2023, Quaternary deposits of the 9-county San Francisco Bay Region: An areally continuous digital map database prepared from Knudsen and others (2000) and Witter and others (2006): U.S. Geological Survey data release, https://doi.org/10.5066/P9OZNPUP.

Wills, C.J., Gutierrez, C.I., Perez, F.G., and Branum, D.M., 2015, A next generation Vs30 map for California based on geology and topography: Bulletin of the Seismological Society of America, 105(6), 3083–3091, https://doi.org/10.1785/0120150105.

Witter, R.C., Knudsen, K.L., Sowers, J.M., Wentworth, C.M., Koehler, R.D., and Randolph C.E., 2006, Maps of quaternary deposits and liquefaction susceptibility in the central San Francisco Bay Region, California: U.S. Geological Survey Open-File Report 2006-1037, 12 pp., https://doi.org/10.3133/ofr20061037.