Bulgarian Seismologist Gergana Georgieva Advances Antarctic Research on Glacier Movements and Earthquakes
Seismologist Gergana Georgieva, from the Faculty of Physics at Sofia University St. Kliment Ohridski, is participating in the Bulgarian Antarctic expeditions for the sixth time to study seismology, Earth's structure, and glacier seismicity.
Her journey began with the goal of installing a seismic station, a project her team initially considered outsourcing before securing funding that allowed her to personally oversee its setup. Georgieva highlighted that this endeavour is a collaborative effort involving ten colleagues in Bulgaria.
When asked why she continues her visits to Antarctica, Georgieva explains: "They say if you come a second time, you never stop at just two visits, and that's exactly what happened to me. But beyond the magic of the place, during my first expedition, I met Spanish seismologists. Engaging with other scientists and the people in this region is part of what makes Antarctica so special. I keep coming back not only for the research but also for the connections I build here. When I study Earth's structure and seismicity in Bulgaria, it attracts little global attention. However, studying the same phenomena in Antarctica garners significant international interest," Georgieva said.
The Bulgarian seismic station is situated 1 km from the base, with another station near the Spanish base Juan Carlos I. In Sally Rocks Bay, seismometers have been installed by scientists from the United Arab Emirates. This year, the Emirati scientists participated in the Bulgarian Antarctic expedition, making their first journey to the Ice Continent with support from the Bulgarian team.
Georgieva explained that while seismographs are commonly associated with recording earthquakes, they actually capture all ground movements as long as they remain powered. Earthquakes represent only 10% of the recorded signals, with the remaining 90% classified as seismic noise. This noise offers valuable insights into the sea, atmosphere, cyclone activity, and iceberg movements. In Antarctica, a substantial part of the data consists of icequakes—seismic events triggered by glacier movements. Additionally, the stations' proximity to the sea enables them to record data on sea waves, tides, and other oceanic phenomena.
Efforts in this field focus on maintaining continuous seismic data, as these records hold long-term value and can be revisited for future research. Advances in scientific methods allow old data to be reanalysed, especially from remote and logistically challenging locations like Antarctica.
"For example, my project near our base investigates the link between glacier movements and earthquakes in the South Bay area. Using the data solely to locate earthquakes around the island would be limiting. In five years, new data processing techniques could emerge, enabling another scientist to use today's recordings for a more comprehensive analysis of the Earth's crust, atmosphere, glaciers, sea, and other phenomena we cannot yet imagine studying," Georgieva said.
The South Shetland Islands and the Bransfield Strait are areas of significant seismic activity. Located 40 km from Livingston Island, the active Deception Volcano is one of the Bransfield volcanoes visible above sea level, alongside several others that remain underwater. Five years ago, two earthquakes with magnitudes of approximately 7 struck near King George Island, while two years ago, a magnitude 5 earthquake occurred in Emona Bay, close to the Bulgarian base. Earthquakes exceeding magnitude 5 are detected by global seismic networks, but weaker tremors, which are more frequent in the region, are recorded only by local seismic stations.
Georgieva explained that icequakes and ice falls can occur as separate phenomena. Icequakes are typically triggered by movements in the upper layers of glaciers. Research has also revealed a link between Antarctic seismic waves and the release of accumulated energy, which leads to increased icequake activity.
"Our seismic station has been operational since 2020, with only a minor data gap of a month and a half this winter," Georgieva said. She expressed hope that new batteries and solar panels would enable uninterrupted recording in the future. "The data we collect is inherently valuable, regardless of the immediate research focus. It provides a foundation for studying seismic activity, sea conditions, and atmospheric changes for years to come."
Georgieva added that studying sea noise, wave activity, and icebergs in the bay is another area of interest. "What fascinates me is how seismic activity in the region evolves. This data will also support geologists in creating more accurate models of geodynamics and tectonics in the area, validating theories about the origin and opening of Bransfield, and offering a comprehensive analysis of Antarctic processes," she said.
The research vessel RSV 421 departed from Varna on its third Antarctic expedition on November 7, 2024, and arrived at Livingston Island on December 28. The St Kliment Ohridski Bulgarian Antarctic Base on Livingston Island opened for the new polar season on November 23, 2024.
BTA has a national press club on the vessel and at the Bulgarian Antarctic base. For the third consecutive year, BTA has sent a correspondent to Antarctica. This year's correspondent, Milena Ostrovska, arrived at the base on January 17. Her reports are freely accessible in English on the Bulgaria-Antarctica BTA's Log section of BTA's website and can be used for free with attribution to BTA.