A VBB Digital Seismograph is so precise that the unit at Harvard's Oak Ridge Observatory in Harvard, Mass., can detect "marine microseisms"--the "motion of the ground generated by wave action against the entire coastline," Steim says. Units in other locations have also detected volcanic explosions, the sonic wave generated by landing space shuttles and even trucks on I-495.

Steim has founded a company named Quanterra that is based in Harvard, Mass. The company was founded to develop and market his technology. Although a seismographic station using his technology currently costs over $150,000, Steim says he hopes to bring the price down to $50,000.

The Big Picture

Harvard has also contributed to the "big picture"--encouraging seismic stations around the world to collaborate and exchange data.

Although there were several attempts to create a global seismograph network in the 1960s and 1970s, Steim says the efforts focused less on science and more on the pressing Cold War need to detect nuclear explosions by measuring their shock waves.

All of that began to change 15 years ago at a meeting at Harvard with the birth of Incorporated Research Institutions for Seismology (IRIS)--a consortium of international seismic research stations funded by the National Science Foundation.

Dziewonski was the first chair of IRIS, and was reelected to serve again in that capacity this year.

"We hope to create, with increasing resolution, a map of the earth's interior," Dziewonski says. "To do this, we essentially have to observe how waves propagate through different parts of the earth."

The signal from an earthquake in China, for example, can travel through the center of the earth at up to 22,000 miles per hour and be felt on the other side of the earth within 20 minutes, according to Dziewonski. But he says that the signals will be slightly different in Paris, New York and Caracas. Analyzing these differences can shed light onto the composition of the earth's interior.

"We think the variations in how the waves propagate in various places relates to the temperature within the earth," Dziewonski says.

To make these calculations possible, IRIS planned and constructed a network of unprecedented scale.

"The idea was to cover the world with a more or less evenly distributed network of some 128 stations...to study the earth's structure in three dimensions," Dziewonski says.

IRIS is close to its goal, with 100 stations already operational in its Global Seismic Network, using state-of-the-art technology 10 to 100 times better than the previous generations of seismographs.

Two-thirds of the IRIS stations are using Steim's equipment, and the data is pouring in. Scientists have already made several discoveries using the network seismographs.

Using digital data from a station in Alaska, scientists at Columbia University last year discovered that the Earth's inner core rotates faster than its mantle.