Transcript SOPAC_NAREF - Scripps Orbit and Permanent Array Center

SOPAC's Instantaneous Global Plate Motion Model:
Contributions to a North America Fixed Reference Frame
Yehuda Bock, Linette Prawirodirdjo, Peng Fang,
Paul Jamason, Shimon Wdowinski (TAU, UMiami)
Scripps Orbit and Permanent Array Center
Institute of Geophysics and Planetary Physics
Scripps Institution of Oceanography
University of California San Diego
La Jolla, California
2004 Joint Assembly
Montreal, CANADA
May 18, 2004
Introduction
SOPAC estimates monthly a global plate motion
model (17 major and minor plates) based on its
daily CGPS position time series.
 Longest time series are 13 years old, beginning
during the “GIG” experiment in January 1991.
Shortest time series are about 4 years old.
 Plate motion model is based on CGPS stations
whose data are publicly available so that it can be
easily used/replicated by other researchers.

GPS Data Analysis
Entire daily time series have been re-estimated by
SOPAC in a consistent manner after a reconciliation
of all site metadata in the SOPAC archive.
 Time series are from 24-hour GAMIT solutions of 20
sub-networks, including 4 global and 16 regional
sub-networks with overlapping sites.
 Sub-networks are combined daily with the GLOBK
glorg module, aligned by a 7-parameter similarity
transformation to ITRF2000 as realized by the IGS,
thereby maintaining the No-Net-Rotation condition of
ITRF2000 wrt to NNR-NUVEL-1A.

Time Series Analysis
Modeled with linear rates (velocities), annual and
semi-annual parameters, offsets (instrumental and
coseismic), and postseismic decay.
 Coefficients of a white noise plus flicker noise model
are estimated by MLE approach, and propagated to
uncertainties of time series parameters.

13-Year Daily (Unfiltered) Time Series at PIN1 & PIN2
PIN1 velocities:
N5.4±0.5;8.0±0.8
E-27.1±0.6;-27.0±0.8
U2.8±1.7;2.7±2.6
PIN2 velocities:
N5.4±0.5;7.5±0.7
E-27.4±0.7;-26.6±1.0
U2.6±1.3;4.1±1.9
RMS:
H 3-4mm;V 9mm
Typical NA Time Series Used in PMM
NA Time Series Excluded from PMM
Plate Motion Model
Stations that exhibit “anomalous” behavior are
excluded (e.g., elastic and seismic deformation,
significant vertical motion).
 Estimate Euler poles by minimizing site
velocities relative to ITRF2000.
 Include in the rigid plate motion estimates only
stations whose velocity residuals are less than
the 2 s velocity uncertainties.
 This leaves us with about 110 global sites.

Velocity differences between SOPAC and ITRF
velocities and comparison of velocity error ellipses –
95% confidence).
Vertical Motions
SOPAC Plate Motion Model
Plate
Lon.
Lat.

(ºE)
(ºN)
º/Myr
c 2
Error Ellipse (º)
smaj
smin
N
Azim.
Anta
-125.655
60.683
0.222±0.006
0.77
0.56
8
1.6
6
Aust
37.590
33.472
0.618±0.003
0.93
0.18
154
1.2
9
Eura
-99.691
57.246
0.260±0.002
0.81
0.18
52
1.1
18
Indi
-41.986
45.720
0.487±0.015
12.11
0.73
29
0.7
2
Noam
-84.702
-3.583
0.200±0.003
0.87
0.25
101
1.3
22
Nubi
-82.685
51.627
0.790±0.004
1.82
0.92
175
0.8
7
Pacf
110.161
-63.832
0.670±0.003
0.59
0.28
2
1.2
5
Soam
-135.798
-21.086
0.108±0.003
6.33
1.80
171
0.4
5
Soma
-106.378
51.305
0.326±0.017
3.87
1.40
36
1.6
3
North America Reference Frame
Examples of Use of Plate Motion Model
SOPAC Online Map Interface
Analysis of SCEC III Crustal Motion Model
Shen et al., 2003
Longitudinal Component
LatitudinalComponent
California Spatial Reference Center (CSRC)
Provide the necessary
geodetic services to ensure the
availability of accurate,
consistent, and timely spatial
referencing data.
 Monitor temporal changes in
geodetic coordinates due to
tectonic motion, earthquakes,
volcanic deformation and land
subsidence.
 Establish the legal spatial
reference system for California
(the “CSRS”).

California Spatial Reference System
SECTOR and CSRS Epoch 2004.0
CSRS Epoch 2004.0 is defined as the coordinates (and
velocities) computed by CSRC on 14 April 2004 using data up
to an including 27 March 2004, and will not change.
Monthly SOPAC PMM Updates
SOPAC estimates monthly a global plate motion
model (17 major and minor plates) to improve
precision and reliability as new data become
available.
 Plate motion model is based on CGPS stations
whose data are publicly available so that it can be
easily used/replicated by other researchers.
 The SOPAC PMM provides a baseline against
which anomalous motions (tectonic or otherwise)
can be detected.
