station-specific traveltime tables in a 3d earth
DESCRIPTION
Station-Specific Traveltime Tables In a 3D earth. Goal: improve earthquake locations while minimizing computation effort through precomputation. Three-D earth model elliptical earth model ½ degree resolution, tetrahedral splines based on available structural information Crust 2.0 - PowerPoint PPT PresentationTRANSCRIPT
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Station-SpecificTraveltime Tables In a 3D earth
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Goal:
improve earthquake locations
while
minimizing computation effort through precomputation
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Three-D earth model
elliptical earth model
½ degree resolution, tetrahedral splines
based on available structural informationCrust 2.0Pn tomographySurface wave tomography
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Overall organization into interfaces
Small-scale organization into tetrahedra
Linear interpolation within tetrahedra implying rays that are circular arcs
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First Cut at building a 3-d MODEL
Simplified, 2-layer-crust version of Crust 2.0
on top of AK135 mantle
with sub-Moho velocities adjusted to match
Crust 2.0 Pn velocities
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Strategy
Compute differential traveltimes between
3D model
and
reference vertically-stratified model
one traveltime calculation for each station
gives traveltime correction for earthquake
anywhere in the US to that station
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Examples
Crust2 minus AK135differential traveltimes
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Shadow zone
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Sensitivity Test
Test grid of earthquake hypocenters
Current US station configuration
Traveltimes for 3D model
Location using AK135
Assess location error
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Stations east of California
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Location Errors: = 0.5 degree
Note: this preliminary calculation used data from a limited number of stations