Surface latent heat flux anomalies prior to the Indonesia Mw9.0 earthquake of 2004

The temporal and spatial variations of surface latent heat flux (SLHF) before and after the Mw9.0 earthquake that occurred on the west coast of Sumatra, Indonesia on 26 December 2004 are summarized. It is found that before the earthquake significant SLHF anomalies occurred at the epicentral area and its vicinity. The largest SLHF anomaly oc- curred on the subduction zone in the middle part of Burma micro-plate, where the middle part of the rup- ture zone is located and the aftershocks are concen- trated. The developments of the anomaly involved growing of the anomaly from small to large and spreading of the anomaly from disordered to con- centrated. The anomaly began to occur on the east extensional boundary of the Burma micro-plate and its adjacent oceanic basin, and then propagated to the west compressive boundary, where the subduc- tion zone exists. Finally, the anomaly disappeared after the main shock. The seismic source is consid- ered to be a dissipation system. The increase of stress prior to an earthquake may enhance the ex- change of energy and material between the seismic source system and the outer system, resulting in the increase of the rate of energy exchange between sea surface and atmosphere, which is believed to be the main reason of the generation of SLHF anomaly.