Introduction to the Western US Cordillera (WUSC) Velocity Field

WUSC velocities were obtained from analyses of Global Positioning System (GPS), very long baseline interferometry (VLBI), satellite laser ranging (SLR), and doppler orbitography and radiopositioning integrated by satellite (DORIS) observations (Table 1). We describe these data analyses, including the method that we used to combine the data from these different techniques, in the following section. In most cases, we made use of data products in SINEX format, as opposed to analyzing the raw (RINEX format) space geodetic observables ourselves.

GPS

The GPS data (RINEX and/or SINEX format) that we used were obtained from:

The University NAVSTAR Consortium (UNAVCO)

Scripps Orbit and Permanent Array Center (SOPAC)

The Southern California Earthquake Center (SCEC)

The Smithsonian Astrophysical Observatory (SAO)

VLBI

The VLBI data (SINEX format) that we used were obtained from:

Goddard Space Flight Center (GSFC)

SLR

The SLR data (SINEX format) that we used were obtained from:

Laboratoire de Recherche en Geodesie (LAREG)

DORIS

The DORIS data (SINEX format) that we used were obtained from:

Laboratoire de Recherche en Geodesie (LAREG)

The space geodetic stations that were used in our analyses are listed in Table 2. In several instances, the stations listed in Table 2 represent more than one antenna/monument/technique. The velocities of these antenna/monument groups have been constrained to be equal (Table 3).

Several GPS campaign networks exist in the western US. See the UNAVCO web site, for example. However, with the exceptions of the data products made available by MIT, SCEC, and SAO (Table 1), SINEX files for these campaigns have not yet been made available.

Data reduction

GPS

Analyses of the raw GPS data were performed by SOPAC, Massachusetts Institute of Technology (MIT), SCEC, and the Smithsonian Astrophysical Observatory (SAO) (Table 4). All GPS data were reduced using the GAMIT software [King and Bock, 1997]. Data were processed in batches of one day. The products of these analyses include daily estimates for station positions, Earth orientation parameters, and GPS satellite orbital parameters. Separate (daily) sets of parameter estimates were obtained for each network listed in Table 4.

We combined those daily parameter estimate sets having a common reference epoch using the GLOBK software [Herring, 1998]. The products of these daily combinations are self-consistent sets of station position and Earth orientation parameter estimates for all of the stations in all of the networks represented in the individual parameter estimate sets. That is, after combination, all parameter estimates refer to a common, homogeneous reference frame.

GPS campaigns were treated slightly differently from the daily continuous GPS combinations. For the GPS campagins, all sessions comprising an experiment were stacked to form multiple epoch combinations.

The general "distributed processing" strategy that we employ is discussed in several papers. The interested reader should refer to Blewitt et al. [1993], Feigl et al. [1993] (Appendix A), Dong et al. [1998] and references therein. Bennett et al. [1999] describes our application of this strategy to the WUSC data set.

VLBI

Please refer to GSFC web site for more information about the NASA Space Geodesy Program and GSFC data analyses [Ma and Ryan, 1997]. VLBI SINEX files containing VLBI station position and Earth orientation parameter estimates are available from this web site.

SLR

Please refer to the ITRF web site for more information about International Terrestrial Reference Frame data products from LAREG. SINEX files containing SLR station position and velocity parameter estimates are available from this web site.

DORIS

Please refer to ITRF for more information about International Terrestrial Reference Frame data products from LAREG. SINEX files containing DORIS station position and velocity parameter estimates are available from this web site.

Velocity Field Estimation

We used the parameter estimate sets (SINEX files) from the all of the above mentioned space geodetic techniques to estimate a single self-consistent set of site velocities. We used the GLOBK analysis software [Herring, 1998] to determine these velocity estimates. This estimation was accomplished in two steps. In the first step, we used the SINEX data prodcuts for GPS, which contain site position and Earth orientation estimates, to estimate the velocities of the GPS stations. We did the same for the VLBI. These GPS and VLBI velocity solutions were then saved in separate SINEX files. In the second step, we combined SINEX files containing site velocity estimates for GPS, VLBI, SLR and DORIS. The product of this analysis was a set of velocity estimates for a large number of globally distributed GPS and VLBI stations. A total of 844 space geodetic stations were included in the GLOBK analysis for site velocity.

We excluded from our solution all site position data whose evolution was obviously not well described by a constant velocity, allowing for discrete offsets due to earthquakes, antenna changes, etc. We made no attempt to tie the positions of collocated stations. Instead, we constrained sites within 1 km of one another to have the same velocity, effectively tying the velocities of GPS, DORIS, SLR, and VLBI antennas located at the same site. Table 3 lists the groups of sites to which these constraints were applied. We make no distinction between velocities derived from more than one antenna/technique.

* The variance-covariance matrix of the velocity solution has not been rescaled. * The variance-covariance matrix is based on the least-squares propagation of scaled observation errors and is intended to represent the statistical uncertainty due to errors in the space geodetic measurements. It does not reflect potential deficiencies in the constant velocity model that we adopted to estimate site velocities. Of particular recent concern, for example, is the potential for site specific monument instability, which is suspected to be a non-negligible source of unmodeled signal for many geodetic monuments in California [e.g., Langbein and Johnson, 1997; Zhang et al., 1997]. This is an area of current research.

We determined a North America fixed reference frame by estimating and subtracting from the velocity field that rigid rotation which minimized the residual velocities of some 59 sites assumed to define a stable North America interior.

Solution description

The velocity file (002_wusc.vel) contains the estimates for the three local (NEU) components of the velocity field for 373 sites in North America, in units of mm/yr, in the North America fixed reference frame. Also listed are the geodetic coordinates associated with each datum. The covariance matrix is located below the list of velocity estimates and site coordinates in lower triangular form in units of (mm/yr)**2. The file 002_wusc.gmt lists these same velocities in GMT format for plotting.

The file 002_wusc.ps shows the horizontal components of the velocity estimates throughout the western US. The file 002_noam.ps shows the horizontal components of the velocity estimates for all stations on the North America plate. Triangles show the locations of stations whose velocity estimates are less than 1 mm/yr in the North America fixed reference frame.

Note on the WUSC Reference Frame

The standard WUSC solution is provided in the North America fixed reference frame. The procedure that we followed to obtain this realization is described above. To facilitate modeling of WUSC crustal deformation, which may require velocities in alternative reference frames, we provide WWW based programs that allow you to define your own reference frame. These programs are accessible from the WUSC Map Maker web site.

REFERENCES

 

Bennett, R.A., W. Rodi, and R.E. Reilinger, GPS Constraints 
  on Fault Slip Rates in Southern California and Northern 
  Baja, Mexico, Journ. Geophys. Res., 101, 21,943-21,960, 
  1996.
 
Bennett, R.A., J.L. Davis, P. Elosegui, B.P. Wernicke, J.K. 
  Snow, M.J. Abolins, M.A. House, G. L. Stirewalt, and D. A. 
  Ferrill, Global Positioning System Constraints on Fault 
  Slip Rates in the Death Valley Region, California and 
  Nevada, Geophys. Res. Lett., 24, 3073-3076, 1997.
 
Bennett, R.A., B.P. Wernicke, and J.L. Davis, Continuous 
  GPS measurements of contemporary deformation across the 
  northern Basin and Range province, Geophys. Res. Lett., 
  25, 563-566, 1998.
 
Bennett, R.A., J.L. Davis, and B.P. Wernicke, The Present-day
  pattern of western U.S. Cordillera deformation, Geology, 27, 
  371-374, 1999.
 
Beutler, G., I.I. Mueller, R.E. Neilan, The International GPS
  Service for Geodynamics: development and start of official 
  service on January 1, 1994, Bull. Geod., 68, 39--70, 1994.
 
Blewitt, G, Y. Bock, G. Gendt, Regional clusters and 
  distributed processing.  Proceeding of the IGS Analysis 
  Center Workshop, Ottawa, Oct 12-14, 1993.
 
Bock, Y., S. Wdowinski, P. Fang, J. Zhang, J. Behr, J. 
  Genrich, S. Williams, D. Agnew, F. Wyatt, H. Johnson, S. 
  Marquez, K. Hudnut, R. King, T. Herring, K. Stark, S. 
  Dinardo, W. Young, D. Jackson, and W. Gurtner, Southern 
  California Permanent GPS Geodetic Array: Continuous 
  measurements of regional deformation, J. Geophys. Res.,
  1997.   
 
Boucher, C., Z. Altamimi, M. Feissel, P. Sillard, Results 
  and analysis of the ITRF94, IERS Tech. Note 20, Cent. Bur., 
  Obs. de Paris, Paris, France, 1996.
 
Dong, D., T.A. Herring, and R.W. King, Estimating crustal
  deformation from a combination of terrestrial and 
  space-based data, J. Geod., 1998. 
 
Feigl, K.L., D.C. Agnew, Y. Bock, D. Dong, A. Donnellan,
  B.H. Hager, T.A.  Herring,  D.D. Jackson, T.H. Jordan, 
  R.W. King, S. Larsen, K.M. Larson, M.H. Murray, Z. Shen, 
  and F.H. Webb, Space geodetic measurement of crustal 
  deformation in central and southern California, 1984-1992, 
  J. Geophys. Res. 98, 21,677-21712, 1993. 
 
Herring, T.A., GLOBK: Global Kalman Filter VLBI and GPS 
  analysis program, v.4.1, Mass. Inst. of Technol., 
  Cambridge, 1998.  
 
King, N.E., J.L. Svarc, E.B. Fogleman, W.K. Gross, K.W. 
  Clark, G.D. Hamilton, C.H. Stiffler, and J.M. Sutton, 
  Continuous GPS observation across the Hayward fault, 
  California, 1991-1994, J. Geophys. Res., 100, 20271-20284, 
  1995. 
 
King, R.W. and Y. Bock, Documentation for the MIT GPS 
  analysis software: GAMIT, Mass. Inst. of Technol., 
  Cambridge, 1998.
 
Langbein, J. and H. Johnson, Correlated errors in geodetic 
  time series: implications for time-dependent deformation,
  J. Geophys. Res., 102, 591--603, 1997.
 
Ma, C., and J.W. Ryan, "NASA Space Geodesy Program -- GSFC 
  DATA Analysis -- 1997, VLBI Geodetic Results 1979-1997", 
  August, 1997.  
 
Shen, Z., D. Dong, T. Herring, K. Hudnut, D. Jackson, 
  R. King, S. McClusky, L. Sung, Crustal deformation 
  measured in southern California, EOS Trans. AGU, v. 78, 
  p. 477, 1997.
 
Strange, W. E., A national spatial data system framework
  continuously operating GPS reference stations, 
  Proceedings of the First Federal Geographic Technology 
  Conference. GIS in Government, USA GIS World Fort Collins, 
  CO, USA, 1, 1994.
 
Zhang, J., Y. Bock, H. Johnson, P. Fang, S. Williams, J. 
  Genrich, S. Wdowinski, J. Behr, J., Southern California 
  Permanent GPS Geodetic Array: error analysis of daily 
  position estimates and site velocities, Journ. Geophys. 
  Res., 102, 18,035-18,055, 1997.
  
Table 1. Geodetic networks used to estimate WUSC velocity field.  
-----------------------------------------------------------------
Network | Network  | Data  | Data     | Sample      
Name    | Location | Type  | Location | References
-----------------------------------------------------------------
AKDA      Alaska     CGPS    UNAVCO     J. Freymuller, pers. comm
BARD      No. CA     CGPS    SOPAC      King et al. [1995]    
BARGEN    B&R        CGPS    UNAVCO     Bennett et al. [1998]
CORS      U.S.       CGPS    SOPAC      Strange [1994] 
DORIS     Global     DORIS   LAREG      Sillard et al. [1998]
EBRY      Utah       CGPS    UNAVCO     R. Smith, pers. comm.
EUREF     Europe     CGPS    SOPAC      ???
IGS       Global     CGPS    SOPAC      Beutler et al. [1994]
FSL       Plains     CGPS    SOPAC      ???
PANGA     Pac-NW     CGPS    CWU        M. Miller, pers. comm.
SCEC      So. CA     FGPS    MIT/SCEC   Shen et al. [1998]
SCIGN     So. CA     CGPS    SOPAC      Prescott [1996];
                                        Bock et al. [1997] 
SLR       Global     SLR     LAREG      Sillard et al. [1998]
VLBI      Global     VLBI    GSFC       Ma and Ryan [1997]
YUCC      ECSZ       FGPS    UNAVCO     Bennett et al. [1997]
-----------------------------------------------------------------
 
Table 2. Geodetic stations included in the WUSC velocity solution. 
-----------------------------------------------------------------
0502_GPS 0505_GPS 0506_GPS 0507_GPS 0508_GPS 0509_GPS 0613_GPS 
0704_GPS 0705_GPS 0807_GPS 1109_GPS 67TJ_GPS 7001_GPS ACUT_GPS 
AGUE_GPS ALAM_GPS ALAM_TRX ALBH_GPS ALGO_GPS ALGR_GPS ALIC_GPS 
ALVA_GPS AMC2_GPS AMCT_GPS ANKR_GPS AOA1_GPS AOML_GPS APEX_GPS 
ARE1_GPS AREQ_GPS AREQ_SCA ARGU_GPS AROT_GPS ASA1_GPS ASC1_GPS 
AUCK_GPS AVRY_GPS AZU1_GPS BAHR_GPS BAKO_GPS BALD_GPS BARB_GPS 
BBRY_GPS BEAR_GPS BEAT_GPS BERD_GPS BGIS_GPS BILL_GPS BKMS_GPS 
BLAC_GPS BLAN_GPS BLC1_GPS BLHL_GPS BLUF_GPS BLYT_GPS BMRY_GPS 
BOGT_GPS BOR1_GPS BOTR_GPS BOUC_GPS BRAN_GPS BRAZ_GPS BREA_GPS 
BRIB_GPS BRMU_GPS BRSH_GPS BRUS_GPS BSHM_GPS BSRY_GPS BULL_GPS 
BURN_GPS BUST_GPS CABA_GPS CABL_GPS CAGL_GPS CAHA_GPS CAHU_GPS 
CAJO_GPS CALI_GPS CARG_GPS CARR_GPS CAS1_GPS CAST_GPS CAST_SCA 
CAT1_GPS CATO_GPS CBHS_GPS CCCO_GPS CCCS_GPS CEN2_GPS CEDA_GPS 
CENT_GPS CHAB_GPS CHAF_GPS CHAT_GPS CHAT_IC9 CHER_GPS CHIL_GPS 
CHLO_GPS CHTP_GPS CHUR_GPS CHUR_SCA CIC1_GPS CICE_GPS CIT1_GPS 
CLAI_GPS CLAR_GPS CMBB_GPS CMP9_GPS CNDR_GPS CNWM_GPS COAC_GPS 
COCH_GPS COLL_GPS COND_GPS COON_GPS CORV_GPS COSO_GPS COTR_GPS 
COXO_GPS CP13_GPS CPEI_GPS CRAT_GPS CRFP_GPS CRHS_GPS CRIS_GPS 
CRO1_GPS CRRS_GPS CSDH_GPS CSN1_GPS CUTT_GPS CVHS_GPS DAEJ_GPS 
DAM1_GPS DAN2_GPS DANT_GPS DARW_GPS DAV1_GPS DESO_GPS DEVL_GPS 
DGAR_GPS DHLG_GPS DIAB_GPS DQUA_GPS DRAO_GPS DS10_GPS DS42_GPS 
DSHS_GPS DSSC_GPS DUBO_GPS DUNP_GPS DYER_GPS DYHS_GPS E122_GPS 
ECCO_GPS ECHO_GPS ECHO_SCA EGAN_GPS EISL_GPS ELAT_GPS ELKO_GPS 
ELSC_GPS ENDD_GPS EOUT_GPS ESRE_GPS ESRW_GPS EWPP_GPS EXTR_GPS 
F726_GPS FAIR_GPS FARB_GPS FBYN_GPS FERN_GPS FIBR_GPS FLAT_GPS 
FLIN_GPS FOOT_GPS FORD_GPS FORT_GPS FORT_V93 FRED_GPS FRIN_GPS 
FTOR_GPS GABB_GPS GALA_GPS GARL_GPS GAVI_GPS GDAC_GPS GILB_GPS 
GLOC_GPS GLSV_GPS GOBS_GPS GODE_GPS GOL2_GPS GOLD_GPS GOPE_GPS 
GOSH_GPS GOUD_GPS GRAP_GPS GRAS_GPS GRAZ_GPS GREE_GPS GUAM_GPS 
HAMA_GPS HAPY_GPS HARK_GPS HART_GPS HARV_GPS HATL_GPS HAWE_GPS 
HBRK_GPS HEBE_GPS HECT_GPS HERS_GPS HKLO_GPS HOB1_GPS HOB2_GPS 
HOBA_GPS HODG_GPS HOFN_GPS HOLB_GPS HOLC_GPS HOLL_GPS HOLP_GPS 
HOPB_GPS HOPP_GPS HRAO_GPS HUNT_GPS HVLK_GPS IISC_GPS INEG_GPS 
IPE0_GPS IRKT_GPS JACK_GPS JNPR_GPS JOHN_GPS JOZE_GPS JPLM_GPS 
JPLR_GPS JRO1_GPS JTNT_GPS JTRE_GPS JUNC_GPS KABR_GPS KARR_GPS 
KATZ_GPS KELS_GPS KELY_GPS KERG_GPS KIRU_GPS KIT3_GPS KNOL_GPS 
KOKB_GPS KOKE_GPS KOKR_GPS KOKT_GPS KOSG_GPS KOUR_GPS KSTU_GPS 
KWJ1_GPS L589_GPS LACU_GPS LAMA_GPS LANW_GPS LASC_GPS LASE_GPS 
LAZY_GPS LBC1_GPS LBC2_GPS LBCH_GPS LDES_GPS LEEF_GPS LEEP_GPS 
LEWI_GPS LFRS_GPS LHAS_GPS LIN1_GPS LIND_GPS LIND_SCA LINJ_GPS 
LITT_GPS LLCO_GPS LMNO_GPS LMUT_GPS LONG_GPS LOSP_GPS LOVE_GPS 
LPGS_GPS LPHS_GPS LPUR_GPS LTHM_GPS LUTZ_GPS MAC1_GPS MADC_GPS 
MAG0_GPS MALI_GPS MAMM_GPS MAS1_GPS MATE_GPS MATH_GPS MAW1_GPS 
MAWY_GPS MAYO_GPS MBWW_GPS MCM4_GPS MDAY_GPS MDO1_GPS MDVO_GPS 
MEDI_GPS METS_GPS METZ_GPS MHCB_GPS MILE_GPS MILL_TRX MINE_GPS 
MINS_GPS MKEA_GPS MLFP_GPS MOJA_GPS MOJF_GPS MOJM_GPS MOLA_GPS 
MONB_GPS MONI_GPS MONP_GPS MONT_GPS MONU_GPS MOR1_GPS MPNS_GPS 
MPWD_GPS MRRN_GPS MSOB_GPS MUNS_GPS MUSB_GPS MUSD_GPS MVFD_GPS 
MWTP_GPS N125_GPS NAIU_GPS NALL_GPS NANO_GPS NDBC_GPS NDSK_GPS 
NEAH_GPS NEST_GPS NEV1_GPS NEW1_GPS NEWP_GPS NICO_GPS NIGU_GPS 
NLIB_GPS NOPK_GPS NOTO_GPS NOUM_GPS NRC1_GPS NSSP_GPS NTUS_GPS 
NYA1_GPS NYAL_GPS O217_GPS O225_GPS OAES_GPS OAKD_GPS OAT2_GPS 
OATM_GPS OATT_GPS OBER_GPS OCOT_GPS OCTI_GPS OHIG_GPS ONS0_GPS 
ONSA_GPS ONST_GPS ONYX_GPS OREI_GPS ORVB_GPS OVLS_GPS OVRO_GPS 
OWEN_GPS P807_GPS PABH_GPS PACO_GPS PAIN_GPS PAMA_GPS PARK_GPS 
PATT_GPS PAXU_GPS PBL1_GPS PBL2_GPS PEAR_GPS PENA_GPS PERL_GPS 
PERT_GPS PETP_GPS PETR_GPS PICO_GPS PIE1_GPS PIN1_GPS PIN2_GPS 
PINY_GPS PKDB_GPS PLAT_GPS PLO3_GPS PLTC_GPS PMHS_GPS PMOB_GPS 
POIN_GPS POL2_GPS POTB_GPS POTS_GPS POZO_GPS PPBF_GPS PPT1_GPS 
PRCO_GPS PRDS_GPS PSAR_GPS PSEB_GPS PSWB_GPS PTDU_GPS PTRB_GPS 
PVEP_GPS PVER_GPS PVHS_GPS PVRS_GPS QUIN_GPS RAIL_GPS RAMO_GPS 
RAYO_GPS RBUT_GPS RCAG_GPS RCM5_GPS RCM6_GPS RDOM_GPS REDH_GPS 
REDM_GPS RELA_GPS REPO_GPS REYK_GPS RHCL_GPS RICH_GPS RICM_GPS 
RICT_GPS RM2W_GPS ROBO_GPS ROCH_GPS ROCK_GPS ROGE_GPS RUBY_GPS 
RUS1_GPS RYAN_GPS S300_GPS SACY_GPS SAFE_GPS SAFR_GPS SAN1_SCA 
SANT_GPS SAOB_GPS SATS_GPS SAV1_GPS SCH2_GPS SCIA_GPS SCIP_GPS 
SEAT_GPS SEDR_GPS SELE_GPS SEY1_GPS SFBC_GPS SFER_GPS SHAO_GPS 
SHIN_GPS SHOS_GPS SIO1_GPS SIO2_GPS SIO3_GPS SIPH_GPS SJU5_GPS 
SJUA_GPS SKUL_GPS SLID_GPS SM01_GPS SMEL_GPS SMYC_GPS SND1_GPS
SNHS_GPS SNI1_GPS SNP2_GPS SNPA_GPS SNRI_GPS SNT0_GPS SNTZ_GPS 
SOAP_GPS SODB_GPS SOL1_GPS SOLI_GPS SOLJ_GPS SPJ1_GPS SPK1_GPS 
SPMS_GPS SPMX_GPS STJO_GPS STRI_GPS STRL_GPS SUAA_GPS SUNH_GPS 
SUTB_GPS SUTH_GPS SUWN_GPS T122_GPS TABL_GPS TAEJ_GPS TAHI_GPS 
TAIW_GPS TAS1_GPS TATE_GPS TCUN_GPS TELE_GPS THOU_GPS THTI_GPS 
THU1_GPS TIBB_GPS TID2_GPS TIDB_GPS TINP_GPS TIVA_GPS TIXI_GPS 
TMGO_GPS TONO_GPS TORP_GPS TOST_GPS TOUL_GPS TOW2_GPS TRAK_GPS 
TRAN_GPS TRO1_GPS TRO2_GPS TROM_GPS TROT_GPS TSKB_GPS TSU0_GPS 
TSU1_GPS TSU2_GPS TSUK_GPS TUNG_GPS TWIN_GPS TWIS_GPS UCD1_GPS 
UCL0_GPS UCLA_GPS UCLP_GPS UCLU_GPS UCSB_GPS UPSA_GPS USC1_GPS 
USC1_SCA USNO_GPS USU3_GPS USUD_GPS USUX_GPS VA01_GPS VAN1_GPS 
VARN_GPS VCIO_GPS VENI_GPS VILL_GPS VNCX_GPS VNDN_GPS VNDP_GPS 
VTIS_GPS VYAS_GPS WAHO_GPS WCHS_GPS WD11_GPS WES1_GPS WES2_GPS 
WETI_GPS WFRD_GPS WHC1_GPS WHI1_GPS WHIT_GPS WHN1_GPS WIDC_GPS 
WIDE_GPS WILL_GPS WINT_GPS WLCI_GPS WLPS_GPS WLSN_GPS WNFL_GPS 
WORK_GPS WSFD_GPS WSFM_GPS WSLR_GPS WSMN_GPS WSRT_GPS WTZ1_GPS 
WTZM_GPS WTZR_GPS XIAN_GPS YAKA_GPS YAKZ_GPS YAM2_GPS YAR1_GPS 
YBHB_GPS YELL_GPS YKN1_GPS YKNA_GPS YKNF_GPS YUNG_GPS ZECK_GPS 
ZIMM_GPS ZWEN_GPS YEBES___ ROBLED32 DSS65___ FORTLEZA OHIGGINS 
SC-VLBA_ SANTIA12 HAYSTACK WESTFORD HN-VLBA_ GGAO7108 GORF7102 
MARPOINT ALGOPARK NRAO20__ NRAO85_1 NRAO_140 NRAO85_3 RICHMOND 
MIAMI20_ NL-VLBA_ FD-VLBA_ HRAS_085 FTD_____ MCD_7850 PLATTVIL 
LA-VLBA_ PIETOWN_ VERNAL__ KP-VLBA_ FLAGSTAF YUMA____ YELLOWKN 
YLOW7296 ELY_____ BLKBUTTE OCOTILLO DEADMANL MON_PEAK PINFLATS 
GOLDVENU DSS15___ MOJAVE12 MOJ_____ PBLOSSOM JPL__MV1 OV-VLBA 
OVRO_130 PVERDES_ MAMMOTHL SANPAULA PENTICTN BR-VLBA_ VNDNBERG 
QUINCY__ HATCREEK FORTORDS FORT_ORD PRESIDIO PT_REYES VICTORIA 
WHTHORSE YAKATAGA SOURDOGH GILCREEK KODIAK__ MK-VLBA_ KOKEE___ 
KAUAI___ SNDPOINT NOME____ KWAJAL26 MARCUS__ 1543_VLB DSS45___ 
PARKES__ HOBART26 TITIJIMA MIZNAO10 KASHIMA_ KASHIM34 TSUKUBA_ 
NOBEY_6M USUDA64_ SAGARA__ MIYAZAKI DAITO___ SESHAN25 URUMQI__ 
CRIMEA__ HARTRAO_ METSHOVI TROMSONO MATERA__ NOTO____ 7593_VLB 
WETTZELL TRYSILNO ONSALA60 NYALES20 MEDICINA EFLSBERG 7840_COM 
7546_COM 7236_COM 7090_COM 7847_G1B 7597_COM 8834_COM 7599_COM 
7834_COM 7596_COM 7837_COM 1181_COM 7836_COM 7838_COM 7543_COM 
7843_COM 7943_COM 7839_COM 7540_COM 7541_COM 7939_COM 7092_COM 
7811_COM 7602_COM 7520_COM 7502_COM 7210_COM 7120_COM 7121_COM 
7123_COM 7525_COM 7124_COM 7515_COM 7940_COM 7109_COM 7886_COM 
7051_COM 7560_COM 1884_COM 1885_G1B 7805_COM 7084_COM 7114_COM 
7853_COM 7896_COM 7288_COM 7265_COM 7085_COM 7115_COM 7110_COM 
7220_COM 7274_COM 7894_COM 7891_COM 7892_COM 7097_COM 7122_COM 
7112_COM 7086_COM 7885_COM 7080_COM 7850_COM 7501_COM 7295_COM 
7410_COM 7063_COM 7065_COM 7102_COM 7103_COM 7105_COM 7106_COM
7918_COM 7919_COM 7125_COM 7920_COM 7130_COM 7104_COM 7101_COM 
7100_COM 7899_COM 7403_COM 7907_COM 7091_COM 7400_COM 7404_COM 
7067_COM 7831_COM 7589_COM 1893_COM 1873_COM 7561_COM 7833_COM 
8833_COM 7835_COM 7810_COM 7548_COM 7545_COM TLSA_COM TLHA_COM 
SPIA_COM YARA_COM GUAB_COM ORRA_COM ORRB_COM KOKA_COM HUAA_COM 
PAPB_COM FAIA_COM DIOA_COM META_COM GOLA_COM GOMA_COM GOMB_COM 
YELA_COM EASA_COM HBKA_COM HBLA_COM RIDA_COM RICA_COM AREA_COM 
SAOB_COM SANA_COM RIOA_COM RIOB_COM KRUA_COM KRUB_COM REYA_COM 
KITA_COM KITB_COM KERA_COM KERB_COM 
--------------------------------------------------------------
 
Table 3. Groups of monuments/antennae within 1 km of one 
another and for which velocity estimates were equated.
--------------------------------------------------------
ROBLED32 DSS65___ 
FORT_GPS FORT_V93 FORTLEZA 
OHIG_GPS OHIGGINS 
SC-VLBA_ CRO1_GPS 
RIOB_COM RIOA_COM 
SANTIA12 7404_COM SANT_GPS SAOB_COM 7400_COM 
7091_COM HAYSTACK 
ARE1_GPS AREQ_GPS 7403_COM AREA_COM 7907_COM AREQ_SCA 
WSFD_GPS WSFM_GPS WES1_GPS WES2_GPS WESTFORD WFRD_GPS 
7899_COM 7100_COM 7101_COM 7104_COM GGAO7108 GODE_GPS
GODE_GPS 7125_COM 7130_COM 7920_COM 7105_COM 7063_COM
7063_COM 7918_COM 7919_COM 7065_COM 7102_COM
7102_COM 7103_COM GORF7102 7106_COM 
7410_COM ALGO_GPS ALGR_GPS AROT_GPS ALGOPARK 
NRAO20__ NRAO85_1 NRAO_140 
RCM5_GPS RCM6_GPS RICT_GPS RICH_GPS 7295_COM RICM_GPS
RICM_GPS RICHMOND MIAMI20_ 
RICA_COM RIDA_COM 
NL-VLBA_ NLIB_GPS 
CHUR_SCA CHUR_GPS 
FD-VLBA_ HRAS_085 FTD_____ 
MDO1_GPS 7850_COM MCD_7850 7080_COM 7086_COM 7885_COM 
AMCT_GPS AMC2_GPS 
PLTC_GPS 7112_COM PLAT_GPS PLATTVIL 
PIE1_GPS PIETOWN_ 
EISL_GPS 7097_COM EASA_COM 
VERNAL__ 7892_COM 
7891_COM FLAGSTAF 
7894_COM YUMA____ 
YKNF_GPS YELLOWKN YLOW7296 YELA_COM YKNA_GPS YKN1_GPS
YKN1_GPS YELL_GPS 
CRIS_GPS COXO_GPS 
BLAC_GPS BLKBUTTE 
OCOT_GPS OCOTILLO 
WAHO_GPS RM2W_GPS 
0807_GPS HECT_GPS 
MONP_GPS 7110_COM MONU_GPS 7274_COM MON_PEAK 7220_COM 
PIN2_GPS PIN1_GPS PINFLATS PINY_GPS 
REPO_GPS MILE_GPS 
CRAT_GPS BLC1_GPS 
CIC1_GPS CICE_GPS 
DAN2_GPS DANT_GPS 
GOMA_COM GOMB_COM 7115_COM GOLDVENU 
BBRY_GPS BEAR_GPS 
7085_COM DSS15___ DS10_GPS GOLD_GPS GOL2_GPS 
MOJAVE12 MOJA_GPS MOJF_GPS MOJM_GPS 7265_COM 7288_COM
7288_COM MOJ_____ GOLA_COM 
SIO3_GPS SIO1_GPS SIO2_GPS 
SJUA_GPS SJU5_GPS 
SNT0_GPS SNTZ_GPS 
PEAR_GPS PBLOSSOM 
WHC1_GPS WHI1_GPS 
ECHO_SCA WLSN_GPS 
HOLP_GPS HOLL_GPS 
JPLR_GPS 7896_COM JPLM_GPS JPL__MV1 
OV-VLBA  OVRO_130 
USC1_GPS USC1_SCA 
OVRO_GPS OWEN_GPS 7853_COM 7114_COM 7084_COM 
LEEP_GPS CAHA_GPS 
PVER_GPS PVERDES_ PVEP_GPS 
UCL0_GPS UCLA_GPS UCLP_GPS 
OATT_GPS PICO_GPS SAFE_GPS OATM_GPS OAT2_GPS SAFR_GPS 
CHAT_IC9 CHTP_GPS 
CAST_SCA CATO_GPS 
MWTP_GPS MAMM_GPS MAMMOTHL 
SNPA_GPS SANPAULA 
PENTICTN DRAO_GPS 
LACU_GPS RCAG_GPS 
CENT_GPS CEN2_GPS 
CARG_GPS CARR_GPS 
VNDN_GPS VNDNBERG VNDP_GPS 
7051_COM QUIN_GPS QUINCY__ 7109_COM 7886_COM 
HATL_GPS HATCREEK 
FTOR_GPS FORT_ORD 
PBL1_GPS PBL2_GPS 
VICTORIA ALBH_GPS 
GILCREEK FAIR_GPS 
7124_COM THTI_GPS TAHI_GPS PAPB_COM 
7123_COM 7121_COM HUAA_COM 
MK-VLBA_ MKEA_GPS 
7210_COM 7120_COM 
KOKT_GPS KOKE_GPS KOKR_GPS KOKB_GPS KOKEE___ KAUAI___ 
KAUAI___ KOKA_COM 
KWAJAL26 7092_COM 
PETP_GPS PETR_GPS 
1543_VLB TID2_GPS DS42_GPS TIDB_GPS DSS45___ 
ORRA_COM ORRB_COM 7843_COM 
HOBART26 HOBA_GPS TAS1_GPS HOB1_GPS HOB2_GPS 
KASHIMA_ KASHIM34 
TSUK_GPS TSU0_GPS TSU1_GPS TSKB_GPS TSU2_GPS TSUKUBA_ 
USUDA64_ USUD_GPS USUX_GPS USU3_GPS 
YAKA_GPS YAKZ_GPS 
SHAO_GPS SESHAN25 7837_COM 
YAR1_GPS 7847_G1B 7090_COM YARA_COM 
KERA_COM KERB_COM KERG_GPS 
KIT3_GPS KITA_COM KITB_COM 
7561_COM 1873_COM 
CRIMEA__ 1893_COM 
7589_COM ANKR_GPS 
HART_GPS HARK_GPS HBLA_COM HBKA_COM 
HRAO_GPS 7501_COM HARTRAO_ 
METS_GPS 7805_COM 
META_COM METSHOVI 
1884_COM 1885_G1B 7560_COM 
DIOA_COM 7940_COM 7515_COM 
SUTH_GPS 7502_COM 
TRO1_GPS 7602_COM TROMSONO TROM_GPS TRO2_GPS TROT_GPS 
7811_COM BOR1_GPS 
7939_COM 7540_COM MATE_GPS 7541_COM MATERA__ 
GRAZ_GPS 7839_COM 
NOTO_GPS NOTO____ 7543_COM 
POTS_GPS 1181_COM 7836_COM 
WTZR_GPS WTZ1_GPS 7596_COM WETI_GPS WTZM_GPS 7597_COM
7597_COM 7834_COM 8834_COM
8834_COM 7599_COM 7593_VLB WETTZELL 
ONSALA60 ONSA_GPS ONS0_GPS ONST_GPS 
NYALES20 NYA1_GPS NALL_GPS NYAL_GPS 
MEDICINA MEDI_GPS 7546_COM 
7545_COM CAGL_GPS 7548_COM 
ZIMM_GPS 7810_COM 
7835_COM GRAS_GPS 
8833_COM 7833_COM KOSG_GPS 
TLHA_COM TLSA_COM 
HERS_GPS 7840_COM 
--------------------------------------------------------
 
Table 4. Analyses of the raw data used to estimate the 
WUSC velocity field.   
---------------------------------------------------------
Network | Analysis   | Time    | Analysis   
Name    | Software   | Span    | Group     
---------------------------------------------------------
AKDA     GAMIT        1999-2000  SAO
BARD     GAMIT        1996-2000  SOPAC 
BARGEN   GAMIT        1996-2000  SAO
CORS     GAMIT        1996-2000  SOPAC 
DORIS    GINS/DYNAMO  1990-1998  GRGS, CSR, IGN
EBRY     GAMIT        1997-2000  SAO
EUREF    GAMIT        1999-2000  SAO
FSL      GAMIT        1996-2000  SOPAC
IGS      GAMIT        1996-2000  SOPAC
PANGA    GAMIT        1997-2000  SAO
SCEC     GAMIT        1986-1997  SCEC 
SCIGN    GAMIT        1996-2000  SOPAC 
SLR      ?????        1976-1998  CGS, CSR, DUT, GSFC, GZ 
VLBI     CALC/SOLVE   1979-1998  GSFC 
YUCC     GAMIT        1991-1997  SAO 
---------------------------------------------------------
 
 
Table 5. Sites used to define the North America 
fixed reference frame
-----------------------------------------------
KELY_GPS STJO_GPS BRMU_GPS SCH2_GPS THU1_GPS 
HAYSTACK WES2_GPS HN-VLBA_ MOR1_GPS NRC1_GPS 
WLPS_GPS SOL1_GPS GODE_GPS MARPOINT STRL_GPS
ALGO_GPS NRAO_140 NRAO85_3 RCM6_GPS RICA_COM
SAV1_GPS NLIB_GPS CHUR_GPS DQUA_GPS NDSK_GPS
PATT_GPS HKLO_GPS DUBO_GPS HBRK_GPS LMNO_GPS 
PRCO_GPS HVLK_GPS VCIO_GPS JTNT_GPS FLIN_GPS
GDAC_GPS TCUN_GPS FD-VLBA_ MDO1_GPS PLTC_GPS
TMGO_GPS LA-VLBA_ WSMN_GPS PIE1_GPS VERNAL__
7122_COM CAST_GPS HEBE_GPS KP-VLBA_ FLAGSTAF
FERN_GPS FRED_GPS PENA_GPS YUMA____ YELL_GPS
PRDS_GPS ENDD_GPS BLYT_GPS FAIR_GPS

For further information contact:

Richard Bennett
Harvard-Smithsonian Center for Astrophysics
60 Garden St, MS 42
Cambridge, MA 02138-1516
(617) 496-7811