NEW VERSION OF THE HORIZONTAL TIME DEPENDANT POSITIONING (HTDP) TOOL

May 20, 2008

NEW VERSION OF THE HORIZONTAL TIME DEPENDANT POSITIONING (HTDP) TOOL

NOAA's National Geodetic Survey recently released version 3.0 of
the HTDP software for transforming positional coordinates and/or geodetic=

observations across time and between spatial reference frames.

Read more at:

        http://www.ngs.noaa.gov/PC_PROD/HTDP/news.shtml

NOAA=E2=80=99s National Geodetic Survey recently released version 3.0 of =
the Horizontal Time-Dependent Positioning (HTDP3.0) software=20
for transforming positional coordinates and/or geodetic observations acro=
ss time and between spatial reference frames. Users=20
may also apply HTDP3.0 to predict velocities and displacements associated=
with crustal motion in any of several popular=20
reference frames; including NAD 83, WGS 84, and ITRF.

HTDP3.0 introduces a new model for horizontal crustal velocities across w=
estern CONUS within the region bounded in latitude by=20
31=C2=BAN and 49=C2=BAN and in longitude by 100=C2=BAW and 125=C2=BAW. D=
eveloped by Dr. Robert McCaffrey, this velocity model represents western =

CONUS as a collection of elastic, rotating crustal blocks that are separa=
ted by geologic faults. Dr. McCaffrey used 4,890=20
GPS-derived horizontal velocities, 170 fault slip rates, and 258 fault sl=
ip vectors to estimate various model parameters (block=20
motion, internal block deformation, and fault slip rates).

HTDP3.0 also introduces a model for the displacements associated with the=
magnitude 7.9 Denali earthquake that devastated=20
central Alaska on November 3, 2002. This earthquake model was developed =
by researchers at the University of Alaska at Fairbanks.