NEW NEOTECTONIC FEATURES MAP COMPILATION OF THE SIERRA NEVADA, CALIFORNIA AND NEVADA

We present a newly compiled map of Neotectonic Features for the Sierra Nevada, prepared as part of the upcoming Sierra Nevada Digital Earth Science Atlas. This map, prepared at 1:400k scale, shows Quaternary faults, historical seismicity, recent volcanism, and geothermal features data layers that express recent tectonism.

Quaternary faults were compiled and slightly modified from the USGS and CGS Quaternary Faults database and were generalized for display at 1:400k scale. These features show the strike-slip and normal faulting that defines the Walker Lane, marking the broad transition between the Sierra Nevada block to the west and the Basin and Range province to the east. In the southwest portion of the study area the San Andreas fault system reflects the dominant transform plate boundary. The paucity of Quaternary faults within the Sierra Nevada and the Great Valley reflects the low deformation rates within the block, although some Quaternary faults are present at the boundary of the two regions.

Historical seismicity data for earthquakes of M >= 3.5 were compiled from multiple sources, including the USGS Advanced National Seismic System, CGS, and the Northern California Earthquake Data Center. Seismicity has been concentrated along faults of the Walker Lane, at volcanic centers east of the Sierra, along the southeast margin of the San Joaquin Valley, and in the Big Bend region of the San Andreas fault, and is associated with recent large earthquakes, such as the 2019 Ridgecrest sequence. The Sierra Nevada and the Great Valley have experienced much sparser historical seismicity.

Volcanic centers with documented late Pleistocene to Holocene eruptions were compiled. The Lassen volcanic center (just beyond the northwest map extent) represents the southern extent of the modern Cascade arc and erupted as recently as 1914-1917 AD. All other volcanic centers are distributed along the eastern boundary of the Sierra and are associated with extensional and transtensional tectonics in this region. Here, at least three eruptions have occurred in the past ~700 years.

Geothermal features include hot springs, fumaroles, and areas of CO₂ seepage, many of which are genetically associated with ongoing magmatism or spatially associated with Quaternary faults, which can serve as conduits for magmatic gases and hydrothermal fluids.