Interesting this earthquake struck shortly after a solar eclipse, implying significant spring tide forces were present. The earthquake occurred near dawn, when

Interesting this earthquake struck shortly after a solar eclipse, implying significant spring tide forces were present. The earthquake occurred near dawn, when the sun/moon pair, Indonesia, and the Earth's core formed a right angle to each other, creating tidal tension forces on the crust. Tidal forces have been linked to the Dec. 26, 2004 Sumatra earthquake. This paper claims there's a significant link between tidal forces and earthquakes in the region (https://doi.org/10.1029/2006GL027074 https://doi.org/10.1029/2006GL027074). The authors conclude "The observed relationships suggest that the cyclical crustal flexing, which will be at a maximum at full or new moons, might provide sufficient extra force to a plate-boundary region already on the point of rupture to trigger an earthquake that was ‘waiting to happen’."