Western U.S. Date of Last Event (DOLE) for use in time-dependent probabilistic seismic hazard analyses

This Data Release contains two compilations provide information on the date of the last known earthquake in the U.S. where available (conterminous U.S. and Alaska). There are two spatial datasets with different feature geometries — line features (“HistDOLE_v1”) and point features (“PaleoDOLE_v1”). The line features describe surface ruptures constrained by historical or near-historical observations (c. 1850). The point features describe paleoseismic observations of the most recent earthquake at a study location. These compilations support future development of time-dependent seismic hazard analyses. Given constraints in their (presently) narrow application, these data (particularly the point data) are not meant to be comprehensive of known or inferred paleoseismic observations across the U.S. For faults with both historic and paleoseismic observations of DOLE, the historic (line feature) takes precedence. For example, there are no paleoDOLE sites included along the 1857 Fort Tejon earthquake (southern San Andreas fault), although there are many paleoseismic sites along this stretch of fault. Instead, the 1857 extent is represented as a line feature in HistDOLE.

We include paleoseismic observations of the most recent earthquake (MRE) that:

Observe primary faulting evidence of the MRE in an excavation (trench) or natural exposure [i.e., exclude observations of scarps on surfaces of known or estimated age]
Use absolute geochronology [i.e., exclude estimates of MRE timing based on superposition, carbonate thickness, soil interpretations, etc...]
Are bounded by minimum and maximum ages [i.e., exclude MRE timings that are maximum age only; for instance, "one event in the past 8,000 years"]
Have a temporally "well constrained" MRE [i.e., exclude records where the age range of MRE timing may exceed the mean recurrence interval of the fault]
Provide additional information on top of the historical surface rupture extents [i.e., exclude sites that are along a historic surface rupture but do not make direct observation of the MRE. The line geometry (HistDOLE) supersedes the point geometry(PaleoDOLE), and duplication is not required]
Are described in a peer-reviewed, publicly available publication [i.e., exclude final technical reports, consulting reports, and other forms of “gray” literature]


Paleoseismic data were compiled from individual publications found through a comprehensive literature search, and studies referenced in the U.S. Quaternary Faults and Folds Database legacy reports (link), UCERF3 Appendix G (Weldon et al., 2013), Utah Working Group on Earthquake Probabilities, Scharer and Yule (2020), and Styron and Sherrod (2021).

Historical rupture extents were compiled from individual publications of surface rupture observations, generalized extents of 'historic' aged faults in the U.S. Quaternary Faults and Folds Database (link), and UCERF3 Time-Dependent rupture extents (link to supplement of Field et al., 2015).

References:
Field, Edward H., et al. (2015) "Long‐term time‐dependent probabilities for the third Uniform California Earthquake Rupture Forecast (UCERF3)." Bulletin of the Seismological Society of America 105.2A: 511-543.
Scharer, K. M., & Yule, D. (2020). A maximum rupture model for the southern San Andreas and San Jacinto faults, California, derived from paleoseismic earthquake ages: Observations and limitations. Geophysical Research Letters, 47(15).
Styron, R. H., & Sherrod, B. (2021). Improving paleoseismic earthquake magnitude estimates with rupture length information: Application to the Puget Lowland, Washington State, USA. Bulletin of the Seismological Society of America, 111(2), 1139-1153.
Weldon, R. J., Dawson, T. E., Biasi, G., Madden, C., & Streig, A. R. (2013). Appendix G: Paleoseismic sites recurrence database. US Geol. Surv. Open‐File Rept. 2013‐1165
Working Group on Utah Earthquake Probabilities (WGUEP), 2016, Earthquake probabilities for the Wasatch Front region in Utah, Idaho, and Wyoming: Utah Geological Survey Miscellaneous Publication 16-3, 164 p., 5 appendices.