Chapter 6: Electrical structure of the crust and upper mantle beneath the United States; Part 1, Methods for determining the conductivity profile

1989 ◽  
pp. 71-90 ◽  
Author(s):  
George V. Keller
Keyword(s):  
United States ◽  
Upper Mantle ◽  
The United States ◽  
Crust And Upper Mantle ◽  
Electrical Structure ◽  
Conductivity Profile

Earthquake energy release and isostasy

1964 ◽  
Vol 54 (2) ◽  
pp. 777-784
Author(s):  
Joseph W. Berg ◽  
Robert Gaskell ◽  
Verrill Rinehart
Keyword(s):  
United States ◽  
Energy Release ◽  
Upper Mantle ◽  
West Indies ◽  
Averaging Method ◽  
The United States ◽  
Crust And Upper Mantle ◽  
Earthquake Energy ◽  
East Indies ◽  
The Relationship

ABSTRACT The relationship between isostatic anomalies and average annual earthquake energy released was investigated. Data were used for the United States, West Indies, East Indies, Japan, Africa, and India. The above areas were subdivided into smaller areas, 5° on the side, and the data for the smaller areas were used to determine a relationship between the variables. Because the data were considerably scattered, an averaging method was used for smoothing. Results of the research indicate that (1) a relationship exists between the average annual earthquake energy released from regions and the isostatic relief (or gradient) of the regions, and (2) the isostatic relief can be used as an index of the strain level of the crust and upper mantle.

Crust and Upper Mantle Structure Beneath the Eastern United States

2021 ◽  
Author(s):  
Chengping Chai ◽  
Charles Ammon ◽  
Monica Maceira ◽  
Herrmann B. Robert
Keyword(s):  
United States ◽  
Upper Mantle ◽  
Mantle Structure ◽  
Eastern United States ◽  
Crust And Upper Mantle ◽  
Upper Mantle Structure

Assessment of seismic tomographic models of the contiguous United States using intermediate-period 3D wavefield simulation

2021 ◽  
Author(s):  
Tong Zhou ◽  
Ziyi Xi ◽  
Min Chen ◽  
Jiaqi Li
Keyword(s):  
United States ◽  
North America ◽  
Upper Mantle ◽  
Waveform Inversion ◽  
Selection Procedure ◽  
3D Models ◽  
Initial Model ◽  
Crust And Upper Mantle ◽  
Data Set ◽  
Wavefield Simulation

Summary The contiguous United States has been well instrumented with broadband seismic stations due to the development of the EarthScope Transportable Array. Previous studies have provided various 3D seismic wave speed models for the crust and upper mantle with improved resolution. However, discrepancies exist among these models due to differences in both data sets and tomographic methods, which introduce uncertainties on the imaged lithospheic structure beneath North America. A further model refinement using the best data coverage and advanced tomographic methods such as full-waveform inversion (FWI) is expected to provide better seismological constraints. Initial models have significant impacts on the convergence of FWIs. However, how to select an optimal initial model is not well investigated. Here, we present a data-driven initial model selection procedure for the contiguous US and surrounding regions by assessing waveform fitting and misfit functions between the observations and synthetics from candidate models. We use a data set of waveforms from 30 earthquakes recorded by 5,820 stations across North America. The results suggest that the tested 3D models capture well long-period waveforms while showing discrepancies in short-periods especially on tangential components. This observation indicates that the smaller-scale heterogeneities and radial anisotropy in the crust and upper mantle are not well constrained. Based on our test results, a hybrid initial model combining S40RTS or S362ANI in the mantle and US.2016 for Vsv and CRUST1.0 for Vsh in the crust is compatible for future FWIs to refine the lithospheric structure of North America.

scholarly journals P Wave Amplitude Decay Offers a Glimpse of Earth's Structure

Eos ◽  
2016 ◽  
Vol 97 ◽  
Author(s):  
Lily Strelich
Keyword(s):  
United States ◽  
Upper Mantle ◽  
Seismic Waves ◽  
Wave Amplitude ◽  
The United States ◽  
Deep Earthquake

Scientists look at deep earthquake signals to map how seismic waves lose energy in the upper mantle across the United States.

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