Abstract

The 2004 Sumatra earthquake was the second largest anywhere in the last 100 years, producing a tsunami that travelled round the whole world and drowned over 200,000 people. It has since been followed by two other large earthquakes in Sumatra, both among the 20 biggest of the large century. The ground movements in these earthquakes dramatically change the landscape and environment of those who live on the coastline, and are part of a sequence of changes that occur on a human time-scale before, during and after the earthquakes, as part of the natural earthquake cycle. If we understand what causes these changes, and can read the signals in the landscape that tell us what part of the cycle we are currently in, we can recognize which areas are loaded and ready to fail in imminent future earthquakes. The Sumatra earthquake sequence has greatly helped us understand these processes and this knowledge, together with education of the local populations, is the best way to prevent a recurrence of the 2004 disaster. This knowledge has also helped us in forensic investigations of past tsunami-generating earthquakes that are well known historic catastrophes, but whose causes and sources are only now being revealed. These include some famous disasters in the ancient Mediterranean world.