It was 5:58 p.m. on Christmas Day 2004 in Golden, Colorado, when the first seismic waves arrived from halfway around the world. A massive magnitude 9.1 earthquake that had just struck off the coast of Sumatra at 7:58 a.m. local time sent vibrations racing through the Earth's crust at several kilometers per second, eventually reaching the sensors that track global seismicity at the USGS National Earthquake Information Center.

Inside the building nestled in the foothills of the Rocky Mountains, the skeleton crew working the holiday shift noticed something dramatic. Their computer screens were lighting up with incoming data from seismic stations across the globe. What first appeared as subtle squiggles quickly grew into dramatic spikes as the primary waves arrived, followed by even larger secondary waves.

Within an hour, despite it being Christmas Day, a team of seismologists had assembled in the center's main operations room. The rounded helicorders or drum recorders zig-zagged displaying real-time seismic data from around the world. The room hummed with focused energy as scientists hunched over keyboards, analyzing the incoming flood of information.

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The most haunting moment came when they realized the danger for the Indian Ocean region. Their scientific training told them that an earthquake this large, in that location, would have displaced an enormous amount of water. Tsunami waves were likely already racing across the ocean at jet-plane speeds.

The team knew that every minute counted. They began reaching out to their international contacts and tsunami warning centers, though at the time there was no comprehensive warning system in the Indian Ocean that could disseminate warnings to the public.

As the scientists worked through the night, reports began trickling in from the region. The first news of devastating tsunami waves hitting coastlines confirmed their worst fears. The earthquake they had measured from their computers in Colorado was unleashing one of the deadliest disasters in recorded history.

The scope of loss became incomprehensible. Entire communities vanished. Villages that had stood for centuries disappeared. The tsunami claimed more lives in a few hours than any other natural disaster of the 21st century.

• Indonesia: Over 167,000 fatalities
• Sri Lanka: More than 35,000 fatalities
• India: Around 18,000 fatalities
• Thailand: Over 8,000 fatalities

And thousands more across other affected nations.

This was the first magnitude 9 or larger earthquake in 40 years. An entire generation of seismologists had not yet seen such a large event. This earthquake was a pivotal moment for USGS earthquake monitoring.

Although the USGS had started to develop modern methods to characterize the size of the largest earthquakes, this one tested these new systems and methods. McCarthy and Benz had drafted white papers to address the missing pieces of technology, notably a new seismic event processing system, which would be called HYDRA, and additional staffing to reduce the time of reporting information about global earthquakes.

And this event was the trigger to make these changes a reality.

The team's response to this event catalyzed significant changes in earthquake monitoring. Their work proved crucial in several ways:

• Development of enhanced methods for rapidly calculating accurate magnitudes for major earthquakes
• Implementation of improved data sharing protocols with international partners
• Creation of new systems for coordinating with tsunami warning centers
• Establishment of 24/7 monitoring operations at the NEIC

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The transition to round-the-clock staffing was announced shortly after the event, marking a significant evolution in the USGS's earthquake monitoring capabilities. This new operational structure ensured that even during holidays and off-hours, a full team would be ready to respond to major seismic events.

Enhancements were made possible by the Fiscal Year 2005 \$8.1 million Emergency Supplemental Appropriation and a $5.4 million request in the FY 2006 President's Budget approved the previous year by Congress.

The experience left an indelible mark on everyone involved. They had been among the first people on Earth to comprehend the scale of what was unfolding, watching data from the instruments as seismic waves rippled through the planet's interior, bringing urgent messages of the disaster that was just beginning half a world away.

Within a few years, NEIC was able to rapidly and accurately report on 15 or more Magnitude 8 or larger earthquakes since, including the magnitude 9 Tohoku, Japan earthquake and tsunami. 

From the 2011 Seismological Research Letters publication 88 hours: The U.S. Geological Survey National Earthquake Information Center response to the March 11, 2011, Mw 9.0 Tohoku earthquake:

“It is illuminating to compare NEIC responses to the 2011 Tohoku and the great Mw 9.1 26 December 2004 SumatraAndaman Islands earthquakes. In the latter case, the initial automatic NEIC solution (not a public release) came after 17 minutes, with an mb of 6.2. After 10 more minutes, an automatic CMT solution gave the first internal indication of the large size of the earthquake, with a moment magnitude of Mw 8.2. One hour and 23 minutes after OT, parameters were publicly released using an Ms magnitude of 8.5. The magnitude was later updated to Mw 8.9 after six hours and 13 minutes, based on the preliminary global CMT (at that time, Harvard CMT) solution. Importantly, at that time NEIC was dependent on others to provide an authoritative measure of earthquake size.”