9 July 2025—The Global Seismographic Network has stations in Ulaanbaatar, Mongolia and Waverly, Tennessee. Its instruments gather ground motion data in the deserts of western China, at the South Pole and in Germany’s Black Forest. And at every moment, these data are broadcast to researchers, monitoring agencies and the public around the world.
“So we have a literal pulse on the planet with this network,” said Carl Tape, a seismologist at University of Alaska Fairbanks and chair of the GSN Advisory Committee. “And it’s not just that we have the pulse of the planet, but it is a highly accurate measurement of that pulse.”
The high-fidelity, state-of-the-art instrumentation at GSN sites is an unmatched eye on the Earth, offering insights into nuclear test explosions, massive tsunamis and volcanic explosions, long-term environmental changes that affect ocean storms and the deep structure of the planet.
Efforts to maintain, expand and fund the GSN over the past 30 years have spurred the development of “a cutting-edge global geophysical instrumentation system” with both long-standing and continually evolving applications, said Richard Aster, professor of geophysics in the Geosciences department at Colorado State University. ”It serves as a success story for global science diplomacy and collaboration.”
“It’s the single best quality seismic network with global distribution that humans have ever made,” said EarthScope Consortium Chief Executive Officer Becks Bendick.
GSN’s family tree
The GSN includes roughly 150 stations (stations sometimes close or relocate over time) that provide real-time, open-access seismic data that span the full range of Earth’s signals from tides to ocean waves, volcanoes, earthquakes and more. The network is operated jointly between the National Science Foundation through EarthScope and the U.S. Geological Survey, in strong coordination with the international seismological community. EarthScope provides overall guidance for the network and operates the Federation of Digital Seismographic Networks (FDSN) network code II component of the GSN, most of which are outside of the United States. The USGS operates the remaining (code IU, IC, and CU) stations through the USGS Albuquerque Seismological Laboratory. GSN data are archived and curated for future use by EarthScope Data Services.
Although there were attempts at establishing an international seismic network beginning as early as the late 19th century, the GSN has its roots in the rapid development of the World-Wide Standardized Seismograph Network in the 1960s. The WWSSN was created in part to meet a growing demand for high-quality seismic monitoring of nuclear explosions. But station COL, the WWSSN (and current GSN) station in Fairbanks, was installed in 1964 just before the magnitude 9.2 Great Alaska earthquake, Tape noted.
“At the time in Alaska, there was one seismic station at Sitka, and along came COL as part of the worldwide seismographic network. Its first big task was recording the second largest earthquake ever known,” he said.
The WWSSN evolved into the Global Digital Seismograph Network in the 1970s. In 1982, the French Global Network of Seismological Broadband Stations (GEOSCOPE) debuted with new 3-component, broadband seismometers. The GSN was introduced in 1988 as part of a proposal by the Incorporated Research Institutions for Seismology (IRIS) to create a similarly equipped community facility, data distribution and archive center, and instrument pool to serve the U.S. and global seismological community.
In 2023, EarthScope began operating the NSF Seismological Facility for the Advancement of Geoscience (SAGE), which manages the NSF portion of the GSN stations. NSF has solicited proposals for a National Geophysics Facility that would combine SAGE and its counterpart the Geodetic Facility for the Advancement of Geoscience (GAGE).
The proposed combination of GPS, GNSS and seismic networks under the new facility “is a beautiful example of how networks like the GSN can actually serve multiple federal agencies and many different interests,” said Bendick. “It’s kind of government efficiency at its best.”
From the crust to the core
The GSN’s ultra-high quality, low-noise, continuous data are at the heart of some of the most exciting geoscience research of the past decades.
Along with gathering information that helps to rapidly locate and characterize earthquakes worldwide, the GSN operates several of its stations as auxiliary stations for the International Monitoring System that tracks nuclear and chemical explosions.
The continuity of operations at GSN stations, some of which have been collecting data since the 1960s, “helps a lot with refining earthquake locations,” said Robert Anthony, a geophysicist at the USGS Albuquerque Seismological Laboratory. “They’re well-calibrated records. If you want to understand historical earthquakes or understand things like how the planet is changing over time, you need these long-running networks in the same locations.”
Recently, data from GSN stations helped researchers track down the source of a week-long “ringing” of the Earth to a massive Greenland landslide and tsunami, and identified the far-ranging impacts of the 2022 Hunga Tonga-Hunga Ha’apai eruption and tsunami, one of the most powerful underwater volcano explosions ever recorded.
“Lots of GSN observations were used in the [Hunga Tonga] study, including the pressure sensors that we use across the network,” Anthony explained. “In addition to the atmospheric Lamb wave, there was a separate, continuous oscillation of the Earth, as the eruption caused a kind of organ pipe resonance in the atmosphere between the surface of the Earth and the top of the [atmospheric] mesopause about 70 kilometers above the Earth’s surface. This effect is somewhat analogous to an opera singer vibrating a wine glass. We saw both the Lamb wave and these oscillations of the planet across the entire GSN.”
Anthony and Aster collaborated on a 2023 study that used GSN data to show that microseism energy—the seismic hum created by the continuous interaction of global ocean waves with the seafloor—has been increasing steadily over the past 30 years. The likely culprit is climate change, which increases the energy of storms and wind over the oceans.
One of Bendick’s favorite discoveries born out of GSN data, collected on repeating earthquakes and nuclear test explosions, is the 2004 study suggesting unexpected changes in the rotation of the Earth’s inner core.
“You can only see something like that by having 50 years’ worth of data, because you can compare waveforms from identical earthquakes on the exact same stations separated by decades and see that they are actually different,” Bendick said. “You can see the core phases actually changing over time, which is so mind-blowing and crazy.”
“Its use cases have evolved so much over time,” she added. “I think it’s one of the most pure scientific examples of ‘if you build it, they will come.’”
Seismic diplomacy
Researchers have proved over and over again that there is outstanding value in keeping the GSN operating without interruption or degradation. But maintaining the hardware, software, data storage and transmission and human expertise of a global seismic network “always was and is an ambitious undertaking that requires—and really supports—a kind of geopolitical cooperation,” said Tape.
“It’s a key part of the history and tradition of the GSN and also our core belief and practices to have strong local collaborations and respect the local scientists we work with,” Bendick agreed.
Each country with a GSN station requires different levels of collaboration. EarthScope and ASL employees are usually the ones to install critical hardware upgrades, but they also conduct workshops for local geophysicists on topics such as cloud-based tools for seismic data processing. Last year, EarthScope and its local partner the Republican Center of Seismic Forecasting Monitoring of the Ministry of Emergency Situations of the Republic of Uzbekistan built a new station in Jizzax, Uzbekistan (JZAX) from scratch, handling everything from meeting with government officials to providing station technical support.
“Science is a place where like-minded people who don’t necessarily share the same political systems or values or cultures can still come together and do something that matters for all of humanity,” Bendick said. “With the GSN, a station in Papua New Guinea doesn’t only serve Papua New Guinea, it serves the whole globe by helping us learn about our planet. And I think that’s amazing.”