The uplift shown by the trend lines are consistent with an elastic
loading/slip dislocation model which predicts that during the interseismic
(loading) period the portion of the upper plate (Sundaland
block) overlying the locked subduction interface is gradually
depressed, while the region landward of the locked fault zone bows
slightly upward (Meltzner et al., 2006). Land uplift means that tide
gauge readings are lower than actual (absolute) and the apparent
rates of sea level change need to be compensated by adding the uplift
rates. After the earthquake, the behaviour at CHON and BANH is
completely different: we notice an abrupt change in trend: from a
gradual rise to a sharp decline, suggesting a strong downward motion.
The combination of landfall and sea level rise worsens the situation for
low-lying urban areas around the western and northern parts of the
Gulf, and this situation is probably even worse for regions located
closer to the 2004 Sumatra-Andaman earthquake epicentre