Ecophysiology of Great Basin and Sierra Nevada Vegetation on Contrasting Soils

1990 ◽  
pp. 143-178 ◽  
Author(s):  
Evan H. DeLucia ◽  
William H. Schlesinger
Keyword(s):  
Sierra Nevada ◽  
Great Basin

Sierra Nevada-Great Basin boundary zone: Earthquake hazard related to structure, active tectonic processes, and anomalous patterns of earthquake occurrence

1980 ◽  
Vol 70 (5) ◽  
pp. 1557-1572
Author(s):  
J. D. VanWormer ◽  
Alan S. Ryall
Keyword(s):  
Sierra Nevada ◽  
Great Basin ◽  
Temporal Variations ◽  
Mono Lake ◽  
Local Network ◽  
Low Velocity ◽  
Owens Valley ◽  
Walker Lake ◽  
Fault Plane Solutions ◽  
The North

abstract Precise epicentral determinations based on local network recordings are compared with mapped faults and volcanic features in the western Great Basin. This region is structurally and seismically complex, and seismogenic processes vary within it. In the area north of the rupture zone of the 1872 Owens Valley earthquake, dispersed clusters of epicenters agree with a shatter zone of faults that extend the 1872 breaks to the north and northwest. An area of frequent earthquake swarms east of Mono Lake is characterized by northeast-striking faults and a crustal low-velocity zone; seismicity in this area appears to be related to volcanic processes that produced thick Pliocene basalt flows in the Adobe Hills and minor historic activity in Mono Lake. In the Garfield Hills between Walker Lake and the Excelsior Mountains, there is some clustering of epicenters along a north-trending zone that does not correlate with major Cenozoic structures. In an area west of Walker Lake, low seismicity supports a previous suggestion by Gilbert and Reynolds (1973) that deformation in that area has been primarily by folding and not by faulting. To the north, clusters of earthquakes are observed at both ends of a 70-km-long fault zone that forms the eastern boundary of the Sierra Nevada from Markleeville to Reno. Clusters of events also appear at both ends of the Dog Valley Fault in the Sierra west of Reno, and at Virginia City to the east. Fault-plane solutions for the belt in which major earthquakes have occurred in Nevada during the historic period (from Pleasant Valley in the north to the Excelsior Mountains on the California-Nevada Border) correspond to normaloblique slip and are similar to that found by Romney (1957) for the 1954 Fairview Peak shock. However, mechanisms of recent moderate earthquakes within the SNGBZ are related to right- or left-lateral slip, respectively, on nearly vertical, northwest-, or northeast-striking planes. These mechanisms are explained by a block faulting model of the SNGBZ in which the main fault segments trend north, have normal-oblique slip, and are offset or terminated by northwest-trending strike-slip faults. This is supported by the observation that seismicity during the period of observation has been concentrated at places where major faults terminate or intersect. Anomalous temporal variations, consisting of a general decrease in seismicity in the southern part of the SNGBZ from October 1977 to September 1978, followed by a burst of moderate earthquakes that has continued for more than 18 months, is suggestive of a pattern that several authors have identified as precursory to large earthquakes. The 1977 to 1979 variations are particularly noteworthy because they occurred over the entire SNGBZ, indicating a regional rather than local cause for the observed changes.

scholarly journals Assimilated diet patterns of American black bears in the Sierra Nevada and western Great Basin, Nevada, USA

Ursus ◽  
2020 ◽  
Vol 2019 (30e3) ◽  
pp. 40
Author(s):  
Jennapher Teunissen van Manen ◽  
Carl W. Lackey ◽  
Jon P. Beckmann ◽  
Lisa I. Muller ◽  
Zheng-Hua Li
Keyword(s):  
Sierra Nevada ◽  
Great Basin ◽  
Black Bears ◽  
Diet Patterns ◽  
American Black ◽  
American Black Bears ◽  
Assimilated Diet

A comparison of western Great Basin paleoclimate records for the last 3000 yr: Evidence for multidecadal- to millennial-scale drought

2021 ◽  
pp. 183-199
Author(s):  
Steve P. Lund ◽  
Larry V. Benson
Keyword(s):  
Sierra Nevada ◽  
Tree Ring ◽  
Great Basin ◽  
Lake Level ◽  
Lake Basin ◽  
Walker Lake ◽  
Pyramid Lake ◽  
The Past ◽  
Hydrological Variability ◽  
Hydrologic Variability

ABSTRACT This paper summarizes the hydrological variability in eastern California (central Sierra Nevada) for the past 3000 yr based on three distinct paleoclimate proxies, δ18O, total inorganic carbon (TIC), and magnetic susceptibility (chi). These proxies, which are recorded in lake sediments of Pyramid Lake and Walker Lake, Nevada, and Mono Lake and Owens Lake, California, indicate lake-level changes that are mostly due to variations in Sierra Nevada snowpack and rainfall. We evaluated lake-level changes in the four Great Basin lake systems with regard to sediment-core locations and lake-basin morphologies, to the extent that these two factors influence the paleoclimate proxy records. We documented the strengths and weaknesses of each proxy and argue that a systematic study of all three proxies together significantly enhances our ability to characterize the regional pattern, chronology, and resolution of hydrological variability. We used paleomagnetic secular variation (PSV) to develop paleomagnetic chronostratigraphies for all four lakes. We previously published PSV records for three of the lakes (Mono, Owens, Pyramid) and developed a new PSV record herein for Walker Lake. We show that our PSV chronostratigraphies are almost identical to previously established radiocarbon-based chronologies, but that there are differences of 20–200 yr in individual age records. In addition, we used eight of the PSV inclination features to provide isochrons that permit exacting correlations between lake records. We also evaluated the temporal resolution of our proxies. Most can document decadal-scale variability over the past 1000 yr, multidecadal-scale variability for the past 2000 yr, and centennial-scale variability between 2000 and 3000 yr ago. Comparisons among our proxies show a strong coherence in the pattern of lake-level variability for all four lakes. Pyramid Lake and Walker Lake have the longest and highest-resolution records. The δ18O and TIC records yield the same pattern of lake-level variability; however, TIC may allow a somewhat higher-frequency resolution. It is not clear, however, which proxy best estimates the absolute amplitude of lake-level variability. Chi is the only available proxy that records lake-level variability in all four lakes prior to 2000 yr ago, and it shows consistent evidence of a large multicentennial period of drought. TIC, chi, and δ18O are integrative proxies in that they display the cumulative record of hydrologic variability in each lake basin. Tree-ring estimations of hydrological variability, by contrast, are incremental proxies that estimate annual variability. We compared our integrated proxies with tree-ring incremental proxies and found a strong correspondence among the two groups of proxies if the tree-ring proxies are smoothed to decadal or multidecadal averages. Together, these results indicate a common pattern of wet/dry variability in California (Sierra Nevada snowpack/rainfall) extending from a few years (notable only in the tree-ring data) to perhaps 1000 yr. Notable hydrologic variability has occurred at all time scales and should continue into the future.

scholarly journals Life Cycle and Mesoscale Frontal Structure of an Intermountain Cyclone

2010 ◽  
Vol 138 (7) ◽  
pp. 2528-2545 ◽  
Author(s):  
Gregory L. West ◽  
W. James Steenburgh
Keyword(s):  
Life Cycle ◽  
Sierra Nevada ◽  
Great Basin ◽  
Salt Lake ◽  
Salt Lake City ◽  
Confluence Zone ◽  
Frontal Structure ◽  
Lake City ◽  
Weather Changes ◽  
Upper Level

Abstract High-resolution analyses and MesoWest surface observations are used to examine the life cycle and mesoscale frontal structure of the “Tax Day Storm,” an intermountain cyclone that produced the second lowest sea level pressure observed in Utah during the instrumented period and the strongest cold frontal passage at the Salt Lake City International Airport in the past 25 years. A key mesoscale surface feature contributing to the cyclone’s evolution is a confluence zone that extends downstream from the Sierra Nevada across the Great Basin. Strong contraction (i.e., deformation and convergence) within this Great Basin confluence zone (GBCZ) forms an airstream boundary that is initially nonfrontal but becomes the locus for surface frontogenesis as it collects and concentrates baroclinicity from the northern Great Basin, including that accompanying an approaching baroclinic trough. Evaporative and sublimational cooling from postfrontal precipitation, as well as cross-front contrasts in surface sensible heating, also play an important role, accounting for up to 40% of cross-front baroclinicity. As an upper-level cyclonic potential vorticity anomaly and quasigeostrophic forcing for ascent move over the Great Basin, cyclone development occurs along the GBCZ and developing cold front rather than within the Sierra Nevada lee trough, as might be inferred from classic models of lee cyclogenesis. Front–mountain interactions ultimately produce a very complex frontal evolution over the basin-and-range topography of northern Utah. The analysis further establishes the role of the GBCZ in intermountain frontogenesis and cyclone evolution. Recognition of this role is essential for improving the analysis and prediction of sensible weather changes produced by cold fronts and cyclones over the Intermountain West.

Forcing Mechanisms for Washoe Zephyr—A Daytime Downslope Wind System in the Lee of the Sierra Nevada

2008 ◽  
Vol 47 (1) ◽  
pp. 339-350 ◽  
Author(s):  
Shiyuan Zhong ◽  
Ju Li ◽  
Craig B. Clements ◽  
Stephan F. J. De Wekker ◽  
Xindi Bian
Keyword(s):  
Pressure Gradient ◽  
Sierra Nevada ◽  
Great Basin ◽  
Regional Scale ◽  
Surface Wind ◽  
Formation Mechanisms ◽  
Climate Data ◽  
Local Pressure ◽  
Interesting Phenomenon ◽  
Downslope Wind

Abstract This paper investigates the formation mechanisms for a local wind phenomenon known as Washoe Zephyr that occurs frequently in the lee of the Sierra Nevada. Unlike the typical thermally driven slope flows with upslope wind during daytime and downslope at night, the Washoe Zephyr winds blow down the lee slopes of the Sierra Nevada in the afternoon against the local pressure gradient. Long-term hourly surface wind data from several stations on the eastern slope of the Sierra Nevada and rawinsonde sounding data in the region are analyzed and numerical simulations are performed to test the suggested hypotheses on the formation mechanisms for this interesting phenomenon. The results from surface and upper-air climate data analyses and numerical modeling indicate that the Washoe Zephyr is primarily a result of a regional-scale pressure gradient that develops because of asymmetric heating of the atmosphere between the western side of the Sierra Nevada and the elevated, semiarid central Nevada and Great Basin on the eastern side of the Sierra Nevada. The frequent influence of the Pacific high on California in the summer season helps to enhance this pressure gradient and therefore strengthen the flow. Westerly synoptic-scale winds over the Sierra Nevada and the associated downward momentum transfer are not necessary for its development, but strong westerly winds aloft work in concert with the regional-scale pressure gradient to produce the strongest Washoe Zephyr events.

The Normal-Faulting 2020 Mw 5.8 Lone Pine, Eastern California, Earthquake Sequence

2020 ◽  
Author(s):  
Egill Hauksson ◽  
Brian Olson ◽  
Alex Grant ◽  
Jennifer R. Andrews ◽  
Angela I. Chung ◽  
...  
Keyword(s):  
Sierra Nevada ◽  
Great Basin ◽  
Plate Boundary ◽  
Warning System ◽  
Seismic Energy ◽  
Normal Faulting ◽  
Owens Valley ◽  
Waveform Data ◽  
Earthquake Early Warning System ◽  
Rupture Length

Abstract The 2020 Mw 5.8 Lone Pine earthquake, the largest earthquake on the Owens Valley fault zone, eastern California, since the nineteenth century, ruptured an extensional stepover in that fault. Owens Valley separates two normal-faulting regimes, the western margin of the Great basin and the eastern margin of the Sierra Nevada, forming a complex seismotectonic zone, and a possible nascent plate boundary. Foreshocks began on 22 June 2020; the largest Mw 4.7 foreshock occurred at ∼6  km depth, with primarily normal faulting, followed ∼40  hr later on 24 June 2020 by an Mw 5.8 mainshock at ∼7  km depth. The sequence caused overlapping ruptures across a ∼0.25  km2 area, extended to ∼4  km2, and culminated in an ∼25  km2 aftershock area. The mainshock was predominantly normal faulting, with a strike of 330° (north-northwest), dipping 60°–65° to the east-northeast. Comparison of background seismicity and 2020 Ridgecrest aftershock rates showed that this earthquake was not an aftershock of the Ridgecrest mainshock. The Mw–mB relationship and distribution of ground motions suggest typical rupture speeds. The aftershocks form a north-northwest-trending, north-northeast-dipping, 5 km long distribution, consistent with the rupture length estimated from analysis of regional waveform data. No surface rupture was reported along the 1872 scarps from the 2020 Mw 5.8 mainshock, although, the dipping rupture zone of the Mw 5.8 mainshock projects to the surface in the general area. The mainshock seismic energy triggered rockfalls at high elevations (>3.0  km) in the Sierra Nevada, at distances of 8–20 km, and liquefaction along the western edge of Owens Lake. Because there were ∼30% fewer aftershocks than for an average southern California sequence, the aftershock forecast probabilities were lower than expected. ShakeAlert, the earthquake early warning system, provided first warning within 9.9 s, as well as subsequent updates.

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