AGU - Geodesy Section

Individual biographies, citations, and responses

2009, Shin-Chan Han

Large-scale Gravity Change Following the 2004 Sumatra-Andaman Earthquake. Image of gravity changes (microGal = 10-8 m/s2) accumulated over 6 months after the earthquake from GRACE satellite measurements, and time series of 15-day mean gravity observations with error bars (black) and the least-square fit (thick gray). Depicted are the combination of predicted coseismic (1-day) and postseismic (viscoelastic) gravity changes from the Maxwell asthenosphere model with the viscosity of 5x1017 Pa s (yellow), 1018 Pa s (cyan), 5x1018 Pa s (blue), and 1019 Pa s (magenta) and from the bi-viscous asthenosphere model (red). (Figure adapted from Han et al. (2006), Crustal dilatation observed by GRACE after the 2004 Sumatra-Andaman earthquake, Science, 313, 658-662, and from Han et al. (2008), Implications of postseismic gravity change following the great 2004 Sumatra-Andaman earthquake from the regional harmonic analysis of GRACE intersatellite tracking data, J. Geophys. Res., 113, B11413.)

2008, Don Chambers

Non-seasonal ocean bottom pressure (OBP) variability in the North Pacific extracted from Gravity Recovery and Climate Experiment (GRACE) data from 2003 until April 2007. The largest variation is related to a trend from lower than normal OBP in 2003 to higher than normal OBP in 2006 and 2007, which is not predicted by data assimilating models, but is observed by two independent satellite measuring systems - GRACE and Jason-1 altimetry corrected for thermal expansion with Argo float data. The observations support a recent theory of an interannual fluctuation in the subtpolar gyre OBP associated with ENSO events. (Figure adapted from Chambers, D. P., and J. K. Willis (2008), Analysis of large-scale ocean bottom pressure variability in the North Pacific, J. Geophys. Res., 113, C11003, doi:10.1029/2008JC004930.)

2007, Mark Tamisiea

Data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission provide an unique regional picture of the earth's ongoing response to the large ice sheets located over Canada during the last ice age (glacial isostatic adjustment or GIA). The positive signal over the region is primarily caused by mantle material flowing back towards the area after being displaced earlier by the weight of the Laurentide ice sheet. The two maxima suggest the ice sheet had at least a two dome structure. The data can also be used to help place constraints on the relative contribution of GIA and mantle convection to the static gravity anomaly over the region. This analysis indicates that the incomplete GIA is responsible for 25% to 45% of the static anomaly. (Figure adapted from Tamisiea et al., Science, 316, 881-883, 2007.)

(Source: Cornée Kreemer (University of Nevada, Reno), winner of the 2010 Geodesy Section Award) Welcome to the Geodesy Section of the American Geophysical Union.



Announcements Officers & committees Awards & Honors Meetings Journals Become a member Bylaws Links Main AGU page Home		Individual biographies, citations, and responses 2009, Shin-Chan Han Large-scale Gravity Change Following the 2004 Sumatra-Andaman Earthquake. Image of gravity changes (microGal = 10-8 m/s2) accumulated over 6 months after the earthquake from GRACE satellite measurements, and time series of 15-day mean gravity observations with error bars (black) and the least-square fit (thick gray). Depicted are the combination of predicted coseismic (1-day) and postseismic (viscoelastic) gravity changes from the Maxwell asthenosphere model with the viscosity of 5x1017 Pa s (yellow), 1018 Pa s (cyan), 5x1018 Pa s (blue), and 1019 Pa s (magenta) and from the bi-viscous asthenosphere model (red). (Figure adapted from Han et al. (2006), Crustal dilatation observed by GRACE after the 2004 Sumatra-Andaman earthquake, Science, 313, 658-662, and from Han et al. (2008), Implications of postseismic gravity change following the great 2004 Sumatra-Andaman earthquake from the regional harmonic analysis of GRACE intersatellite tracking data, J. Geophys. Res., 113, B11413.) 2008, Don Chambers Non-seasonal ocean bottom pressure (OBP) variability in the North Pacific extracted from Gravity Recovery and Climate Experiment (GRACE) data from 2003 until April 2007. The largest variation is related to a trend from lower than normal OBP in 2003 to higher than normal OBP in 2006 and 2007, which is not predicted by data assimilating models, but is observed by two independent satellite measuring systems - GRACE and Jason-1 altimetry corrected for thermal expansion with Argo float data. The observations support a recent theory of an interannual fluctuation in the subtpolar gyre OBP associated with ENSO events. (Figure adapted from Chambers, D. P., and J. K. Willis (2008), Analysis of large-scale ocean bottom pressure variability in the North Pacific, J. Geophys. Res., 113, C11003, doi:10.1029/2008JC004930.) 2007, Mark Tamisiea Data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission provide an unique regional picture of the earth's ongoing response to the large ice sheets located over Canada during the last ice age (glacial isostatic adjustment or GIA). The positive signal over the region is primarily caused by mantle material flowing back towards the area after being displaced earlier by the weight of the Laurentide ice sheet. The two maxima suggest the ice sheet had at least a two dome structure. The data can also be used to help place constraints on the relative contribution of GIA and mantle convection to the static gravity anomaly over the region. This analysis indicates that the incomplete GIA is responsible for 25% to 45% of the static anomaly. (Figure adapted from Tamisiea et al., Science, 316, 881-883, 2007.)