The study of Earth's interior provides the foundation for crustal and lithospheric studies in many different ways. It is not possible to completely understand North America's surface structure and composition without understanding the deep-Earth processes that have formed them. Surprisingly, deep-Earth geology addresses questions that are of societal importance, such as when the next magnetic field polarity flip will occur, with consequent effects on navigation and the amount of solar and cosmic radiation that reaches Earth's surface, and global sea level change caused by large changes in the mean temperature of the upper mantle.
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Visualizations
Many research facilities are using EarthScope instrument data to produce scientific models and visual representations.
SIO Visualization Center
EarthScope Voyager, Jr.
UC Davis KeckCAVES
Deep Earth Structure and Dynamics
A better understanding of deep earth and how the evolution of continental lithosphere is related to upper mantle processes is a primary goal of EarthScope. How and where are forces generated in the upper mantle and how and where are they transferred to the crust are important questions that need answers in order to obtain of this goal.
Maps of temperature (c, d) as estimated from tomographic models for S and P velocity (a, b, respectively) at a depth of 110 km. Faded colors indicate low resolution in the tomographic model. Regions where the two temperature derivatives differ by more than 150 degrees are indicated by hatching. These may be regions of partial melt, high volatile content, or with composition significantly different from the garnet lherzolite composition (67% ol) used in the computations. Figure from: S. Goes and S. van der Lee, 2001, Thermal structure of the North American uppermost mantle inferred from seismic tomography, J. Geophys. Res., in press.
Research Questions
- How and where are forces generated in the upper mantle and transferred to the crust?
- How is evolution of the continents linked to processes in the upper mantle?
- What is the level of heterogeneity in the mid-mantle?
- What is the nature and heterogeneity of the lower mantle and core-mantle boundary?
How EarthScope Is Aiding Resesarchers
EarthScope is providing a unique opportunity to learn about the deep-Earth structure, composition, and dynamics. The scientific questions that can be addressed in the framework of EarthScope fall into two broad classes. The first concerns the connection between the deep mantle and relatively shallow structures that are being sampled seismologically immediately beneath the North American continent. The second concerns the lower mantle and core, for which optimally sampled regions will be elsewhere (e.g., beneath the Pacific Ocean and Central America), with seismic waves traveling from earthquake sources in the western Pacific and South America through the deep mantle to rise again and be detected by USArray seismometers. We have thus chosen to group the questions roughly in order of increasing depth.