HR: 0800h
AN: GC51D-1085    [Abstracts]
TI: Sealevel, global seismicity and tectonics
AU: Melini, D
EM: melini@ingv.it
AF: INGV, via di Vigna Murata 605, Rome, 00143 Italy
AU: * Piersanti, A
EM: piersanti@ingv.it
AF: INGV, via di Vigna Murata 605, Rome, 00143 Italy
AB: Current estimates of secular relative sealevel variations give a uniform rise in the range 1.5-2.0 mm/yr over the last century. The main climatological contributions come from water volume increase due to thermal expansion and water mass increase due to ice melting. The volume increase accounts for a rise of about 0.5 mm/yr while the mass increase is thought to be even smaller. Since earthquakes produce vertical crust displacements and geoid height variations, they change also the relative sea level. On a global scale the combined effect of world seismicity is responsible for a mean relative sealevel variation of 0.1 mm/yr, with a large regional variability. This value is of the same order of magnitude of the climatological contributions and, in sites with strong seismotectonical activity, may represent the dominant contribution of relative sealevel variations measured by tide gauges. The recent measures of sealevel obtained by satellite altimetry show a wide regional variation of sealevel trends over the oceanic surfaces. These measurements, when compared with the global seismic driven signal, show a strong correlation of the geographical distribution of trend signs, while the absolute values of seismic RSL trends are much smaller in magnitude. The physical processes underlying the observed correlation need a deeper analysis to be understood, but we have a strong indication that seismic and tectonic processes plays an important role in the variation of global sealevel.
DE: 8122 Dynamics, gravity and tectonics
DE: 7209 Earthquake dynamics and mechanics
DE: 4556 Sea level variations
DE: 3210 Modeling
DE: 1635 Oceans (4203)
SC: Global Climate Change [GC]
MN: 2004 AGU Fall Meeting