Thickness of Cenozoic deposits and location and geometry of the Las Vegas Valley shear zone, Nevada, based on gravity, seismic-reflection, and aeromagnetic data

Langenheim, Victoria E.; Grow, John A.; Miller, J.J.; Davidson, Jonathan; Robison, E.

doi:10.3133/ofr98576

Cited by 13 publications

(15 citation statements)

References 24 publications

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“…Figure 5 shows the calculated velocities of the two Rayleigh-wave phases. The Rayleigh-wave velocity for the synthetics remains high in the LVV basin, because at 0.1 Hz the wavelength is 10-26 km and Rayleigh-propagation velocity is not strongly affected by the relatively shallow basin, with a thickness not exceeding 4.9 km (Langenheim et al, 1998(Langenheim et al, , 2001. The converted Rayleigh waves traveling in the thickest part of the LVV basin are traveling at 1 km=s.…”

Section: Differential Travel Timesmentioning

confidence: 97%

“…Comparing with Figure 1a,b, it is evident that outside the near-source area, the distribution and geometry of sedimentary basins controls where the higher (darker) ground motions will appear. NSZ is taking good advantage of the basin-depth inputs derived from Saltus and Jachens (1995) and Langenheim et al (1998Langenheim et al ( , 2001. Figure 8b shows the results of a test of the sensitivity of 3D Nevada ShakeZoning PGV predictions to the shallow geotechnical V S30 velocities of the Clark County Parcel Map Fig.…”

Section: Differential Travel Timesmentioning

confidence: 98%

“…1d). The basin models used to create this simulation are the results of Saltus and Jachens (1995) and of Langenheim et al (1998Langenheim et al ( , 2001. The Saltus and Jachens (1995) data yield a rough approximation of basin depths for the entire modeled region.…”

Section: Nevada Shakezoningmentioning

confidence: 99%

“…The Saltus and Jachens (1995) data yield a rough approximation of basin depths for the entire modeled region. Langenheim et al (1998Langenheim et al ( , 2001 collected additional gravity, borehole, and seismic-reflection data to provide a much more detailed basin model in and around LVV (grid maps in Fig. 1a,b; section in Fig.…”

Section: Nevada Shakezoningmentioning

confidence: 99%

“…In addition, ground-motion recordings of this earthquake are available from within LVV. The LVV is the main area of interest for shaking and hazard prediction due to its population, approaching two million; the availability of detailed basinsediment thickness models (Langenheim et al, 1998(Langenheim et al, , 2001; and detailed geotechnical velocities from the Clark County Parcel Map . Clark County, Nevada's Earthquake Parcel Mapping program was a systematic campaign of geotechnical shear-velocity measurements throughout urbanized southern Nevada, completed in 2011 and presented by .…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Validating Nevada ShakeZoning Predictions of Las Vegas Basin Response against 1992 Little Skull Mountain Earthquake Records

Flinchum¹,

Louie²,

Smith³

et al. 2014

Bulletin of the Seismological Society of America

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Over the last two years, the Nevada Seismological Laboratory has developed and refined Nevada ShakeZoning (NSZ) procedures to characterize earthquake hazards in the Intermountain West. Simulating the M L 5.6-5.8 Little Skull Mountain (LSM) earthquake validates the results of the NSZ process and the ground shaking it predicts for Las Vegas Valley (LVV). The NSZ process employs a physics-based finitedifference code from Lawrence Livermore Laboratory to compute wave propagation through complex 3D earth models. Computing limitations restrict the results to low frequencies of shaking. For this LSM regional model the limitation is to frequencies of 0.12 Hz, and below. The Clark County Parcel Map, completed in 2011, is a critical and unique geotechnical data set included in NSZ predictions for LVV. Replacing default geotechnical velocities with the Parcel Map velocities in a sensitivity test produced peak ground velocity amplifications of 5%-11% in places, even at low frequencies of 0.1 Hz. A detailed model of LVV basin-floor depth and regional basin-thickness models derived from gravity surveys by the U.S. Geological Survey are also important components of NSZ velocity-model building. In the NSZ-predicted seismograms at 0.1 Hz, Rayleigh-wave minus P-wave (R − P) differential arrival times and the pulse shapes of Rayleigh waves correlate well with the low-pass filtered LSM recordings. Importantly, peak ground velocities predicted by NSZ matched what was recorded, to be closer than a factor of two. Observed seismograms within LVV show longer durations of shaking than the synthetics, appearing as horizontally reverberating, 0.2 Hz longitudinal waves beyond 60 s after Rayleigh-wave arrival. Within the basins, the current velocity models are laterally homogeneous below 300 m depth, leading the 0.1 Hz NSZ synthetics to show insufficient shaking durations of only 30-40 s.

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Section: Differential Travel Timesmentioning

confidence: 97%

Section: Differential Travel Timesmentioning

confidence: 98%

Section: Nevada Shakezoningmentioning

confidence: 99%

Section: Nevada Shakezoningmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Validating Nevada ShakeZoning Predictions of Las Vegas Basin Response against 1992 Little Skull Mountain Earthquake Records

Flinchum¹,

Louie²,

Smith³

et al. 2014

Bulletin of the Seismological Society of America

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Guidelines and pitfalls of refraction microtremor surveys

Louie

Pancha²,

Kissane³

2021

J Seismol

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The geotechnical industry has widely adopted the refraction microtremor shear-wave velocity measurement technique, which is accepted by building authorities for evaluation of seismic site class around the world. Clark County and the City of Henderson, Nevada, populated their Earthquake Parcel Map with over 10,000 site measurements for building code enforcement, made over a 3-year period. 2D refraction microtremor analysis now allows engineers to image lateral shear-wave velocity variations and do passive subsurface imaging. Along with experience at a basic level, the ability to identify the “no energy area” and the “minimum-velocity envelope” on the slowness-frequency (p-f) image helps practitioners to assess the quality of their ReMi data and analysis. Guides for grading (p-f) image quality, and for estimating depth sensitivity, velocity-depth tradeoffs, and depth and velocity resolution also assist practitioners in deciding whether their refraction microtremor data will meet their investigation objectives. Commercial refraction microtremor surveys use linear arrays, and a new criterion of 2.2% minimum microtremor energy in the array direction allows users to assess the likelihood of correct results. Unfortunately, any useful and popular measurement technique can be abused. Practitioners must follow correct data collection, analysis, interpretation, and measurement procedures, or the results cannot be labeled “refraction microtremor” or “ReMi” results. We present some of the common mistakes and provide solutions with the objective of establishing a “best practices” template for getting consistent, reliable models from refraction microtremor measurements.

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Geophysical constraints on the location and geometry of the Las Vegas Valley Shear Zone, Nevada

Langenheim¹,

Grow²,

Jachens³

et al. 2001

Tectonics

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Thickness of Cenozoic deposits and location and geometry of the Las Vegas Valley shear zone, Nevada, based on gravity, seismic-reflection, and aeromagnetic data

Cited by 13 publications

References 24 publications

Validating Nevada ShakeZoning Predictions of Las Vegas Basin Response against 1992 Little Skull Mountain Earthquake Records

Validating Nevada ShakeZoning Predictions of Las Vegas Basin Response against 1992 Little Skull Mountain Earthquake Records

Guidelines and pitfalls of refraction microtremor surveys

Geophysical constraints on the location and geometry of the Las Vegas Valley Shear Zone, Nevada

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