Physical Sciences and Mathematics Commons^™

Block Modeling With Multiple Fault Network Geometries And A Linear Elastic Coupling Estimator In Spherical Coordinates, Brendan J. Meade, John P. Loveless

Geosciences: Faculty Publications

Geodetic observations of interseismic deformation provide constraints on the partitioning of fault slip across plate boundary zones, the spatial distribution of both elastic and inelastic strain accumulation, and the nature of the fault system evolution. Here we describe linear block theory, which decomposes surface velocity fields into four components: (1) plate rotations, (2) elastic deformation from faults with kinematically consistent slip rates, (3) elastic deformation from faults with spatially variable coupling, and (4) homogeneous intrablock strain. Elastic deformation rates are computed for each fault segment in a homogeneous elastic half-space using multiple optimal planar Cartesian coordinate systems to minimize areal …

From Decades To Epochs: Spanning The Gap Between Geodesy And Structural Geology Of Active Mountain Belts, Richard W. Allmendinger, John P. Loveless, Matthew E. Pritchard, Brendan Meade

Geosciences: Faculty Publications

Geodetic data from the Global Navigation Satellite System (GNSS), and from satellite interferometric radar (InSAR) are revolutionizing how we look at instantaneous tectonic deformation, but the significance for long-term finite strain in orogenic belts is less clear. We review two different ways of analyzing geodetic data: velocity gradient fields from which one can extract strain, dilatation, and rotation rate, and elastic block modeling, which assumes that deformation is not continuous but occurs primarily on networks of interconnected faults separating quasi-rigid blocks. These methods are complementary: velocity gradients are purely kinematic and yield information about regional deformation; the calculation does not …

Predicting The Geodetic Signature Of Mw 8 Slow Slip Events, Brendan J. Meade, John P. Loveless

Geosciences: Faculty Publications

Elastic dislocation models of geodetic measurements

above subduction zones have led to the identification of

MW 6.0– 7.2 slow slip events (SSEs) that release elastic

strain over periods of days to months, but great (MW 8)

SSEs have remained unidentified. We extrapolate

observations of SSE duration and slip magnitude to show

that slip velocity decreases with event magnitude and

predict that the slip velocity of MW 8 SSEs is 50 mm/yr.

The slip velocity for great SSEs may never exceed the

plate convergence rate and thus never produce a reversal

in trench perpendicular motion. Instead, geodetically

constrained estimates of apparent …

Surface Cracks Record Long-Term Seismic Segmentation Of The Andean Margin, John P. Loveless, Richard W. Allmendinger, Matthew E. Pritchard, Jordan L. Garroway, Gabriel González

Geosciences: Faculty Publications

Understanding the long-term patterns of great earthquake rupture along a subduction zone provides a framework for assessing modern seismic hazard. However, evidence that can be used to infer the size and location of past earthquakes is typically erased by erosion after a few thousand years. Meter-scale cracks that cut the surface of coastal areas in northern Chile and southern Peru preserve a record of earthquakes spanning several hundred thousand years owing to the hyperarid climate of the region. These cracks have been observed to form during and/or shortly after strong subduction earthquakes, are preserved for long time periods throughout the …

Magma In A Beaker: Analog Experiments With Water And Various Salts Or Sugar For Teaching Igneous Petrology, John B. Brady

Geosciences: Faculty Publications

Solutions of water and a salt or sugar make excellent experimental analog magmas for teaching concepts of igneous petrology because of the comparatively low temperatures involved, the simplicity of the apparatus needed, and the responsiveness of familiar chemical systems. Boiling of these aqueous solutions on a hot plate can be used to increase the concentration of a dissolved salt or sugar to levels that may be predicted by steam-saturation curves. Sufficiently concentrated solutions will crystallize, partially or completely, upon cooling to room temperature. Binary temperature–composition phase diagrams for H₂O and KCl, NaCl, MgCl₂, CaCl₂, …