Transcript PowerPoint

HTDP: A tool to correct survey data for tectonic motion
Chris Pearson, National Geodetic Survey
Richard Snay, National Geodetic Survey
Rob McCaffrey, Troy Geophysics
Updated model of the secular field
•
•
An analytical model representing
horizontal crustal motion
developed using DEFNODE
– Incorporates all major active
faults in a single model.
– Provides a more accurate
model of crustal deformation
in western US
data comprise
– 4890 GPS velocities
– 170 fault slip rates from
paleoseismic & paleomag studies
– 258 fault slip vectors taken from
earthquakes and geologic studies
Residuals
• Fit with all data sets is excellent
• Of 6462 original velocities, 1570 were
removed for the following reasons:
• either near volcanoes or unmodeled faults
(244),
• high uncertainties (754),
• anomalous velocities (343),
• not within the model region (228)
•
Data Type
GPS
Slip rates
Slip vectors
Total
Num. Data
9780.00
170.00
258.00
10208.00
Nrms
1.15
1.41
0.94
1.16
Wrms
0.98 mm/yr
1.23 mm/yr
12.9º
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Un-modeled deformation
• 6 circular regions were
excluded from the inversion.
These included 4 active
volcanic areas
• Mammoth Lakes Caldera,
Three Sisters Volcanoes,
Yellowstone Caldera and Mt
St Helens Volcano
• Two in southern CA are
associated with un-modeled
post seismic deformation
• We intend to expand the
model to cover these areas
– By fitting a model to the
smoothed residuals
Test of HTDP 3.0
• Testing of HTDP is underway
• So far we have used two data sets.
– The velocities used to develop HTDP
– Velocities for the CORS network
Rob’s data
NGS CORS data