“This paper is highly cited because it was a rapid analysis of the most devastating natural disaster to occur for many decades, with over 225,000 people losing their lives in the tsunami produced by the great earthquake.”

This paper is highly cited because it was a rapid analysis of the most devastating natural disaster to occur for many decades, with over 225,000 people losing their lives in the tsunami produced by the great earthquake. A large number of scientists in the global seismological community worked together under my leadership to quantify the earthquake faulting that caused this disaster.

This was an analysis using many seismological tools to study the event, but the nature of the earthquake required all procedures to be adapted to the special circumstances of the longest length and duration faulting we have ever recorded.

The paper determined how the fault along the Sumatra-Nicobar-Andaman subduction zone ruptured. We determined how much the fault slipped and how variable the slip was as a function of space and time.

We did this by modeling seismic waves recorded around the world and by modeling tsunami signals recorded by a satellite measuring ocean altitude variations. The fault slipped an average of about 10 m over a length of 1300 km and a width of 150-250 km.

I became involved in the earthquake after the first reports of tsunami deaths came in on the day after Christmas in 2004. Examining the seismic recordings available on the web, I quickly realized this was the largest earthquake of the past 40 years, and anticipated that the early death and damage estimates were underestimates.

Over the next week or so the magnitude of the disaster was recognized, and it was apparent to me that seismology should quantify what had happened to inform policy makers and to guide future hazard mitigation efforts like a tsunami warning system. So, in my capacity as Chairman of the Board of Directors of the Incorporated Research Institutions for Seismology, I contacted many members of the global seismological community and asked them to collaborate rather than to pursue individual isolated analyses. This ultimately led to 42 co-authors producing three major seismological papers published in a special section of Science in May 2005, remarkably soon after the event for such detailed quantification of the faulting.

We did encounter challenges in the analysis due to the great size, duration, and complexity of faulting, and all researchers had to modify their software to handle the particular nature of this event. Those modifications are in place and when the next great earthquake occurs we will be able to perform the corresponding analysis in hours rather than weeks.

There will be more great earthquakes around the world and seismological analysis will be the key to understanding them. It also provides the basis for many earthquake forecasting and rapid warning procedures, including being an essential part of tsunami warning systems. Several countries are contributing to a new tsunami warning system for the Indian Ocean to complement the U.S. systems operating in the Pacific and Caribbean Oceans.

Earthquake ruptures are a basic physical phenomenon that elicits great intellectual interest, but they can have huge societal impact, as did this event. The hazards resulting from large earthquakes are in the minds of all seismologists who study earthquake faulting, as we strive to understand the nature of earthquakes, so that we can better prepare and cope with their inevitable occurrence.