A basic understanding of the tectonics of this region would seem to have been enough as well...but it wasn’t.
Something that happens every 500-1000 years is routine in terms of the Earth, but unthinkable to the average person.
I’m sure the Apocalpytikook/”God’s Punishment!” Brigade will ignore this story in their desperate attempts to portray every new natural disaster as something unique and special.
Complicated tectonics. The Indo-Australian plate (upon which the Indian Subcontinent and Australia rest) meets with Asia along the Himalayas (the tectonic collision which led to its rise) and through the islands of South-East Asia.
The dynamics between the meeting-points were responsible for the famous tsunami.