SOPAC's Instantaneous Global Plate Motion Model:

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 AssemblyMontreal, CANADA

May 18, 2004

Contributions to a North America Fixed Reference Frame

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.

Introduction

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.

GPS Data 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.

Time Series Analysis

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

13-Year Daily (Unfiltered) Time Series at PIN1 & PIN2

Typical NA Time Series Used in PMM

NA Time Series Excluded from PMM

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 velocity uncertainties.

This leaves us with about 110 global sites.

Plate Motion Model

Velocity differences between SOPAC and ITRF velocities and comparison of velocity error ellipses – 95% confidence).

Vertical Motions

SOPAC Plate Motion Model

Plate Lon. Lat. Error Ellipse (º)

2

N

(ºE) (ºN) º/Myr maj min 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

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 Center (CSRC)

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.

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.

Monthly SOPAC PMM Updates