Landslide-generated tsunamis can pose severe threats to coastal areas, particularly within narrow fjords where steep cliffs can trap and intensify waves. Unlike earthquake-induced tsunamis, these events are harder to detect using conventional seismic monitoring, which primarily captures ground shaking. The new study demonstrates that shipborne Global Navigation Satellite System (GNSS) technology can effectively detect the subtle vertical movements associated with landslide-triggered tsunamis.
The critical event occurred on May 8, 2022, when a landslide near the port city of Seward, Alaska, sent debris crashing into Resurrection Bay, creating small but powerful tsunami waves. At the time, the R/V Sikuliaq, a National Science Foundation-owned research vessel operated by the University of Alaska Fairbanks, was moored just 650 meters (0.4 miles) from the slide. The ship, equipped with an external GNSS receiver installed by Ethan Roth, its science operations manager, captured the subtle changes in its vertical position as the tsunami waves passed.
"I actually happened to be in Alaska at that time, retrieving seismometers from another study," said Anne Sheehan, a CIRES Fellow and professor of geological sciences at CU Boulder. "I decided to go visit the Sikuliaq, and it turned out that there had been a landslide a day or two before. One of the crew members filmed it, and we thought, 'wow,' this is a great signal to try to find in the data."
Graduate student Adam Manaster led the analysis, using the ship's GNSS data and open-source software to measure changes in its vertical position down to the centimeter level. The team then compared this data to a landslide-tsunami model, confirming that the ship's movement matched the timing and characteristics of the event.
"This research proves that we can utilize ships to constrain the timing and extent of these landslide tsunami events," Manaster said. "If we process the data fast enough, warnings can be sent out to those in the affected area so they can evacuate and get out of harm's way."
The findings build on previous CIRES-led research that showed commercial vessels equipped with real-time GPS could enhance tsunami early warning systems, potentially saving lives. However, widespread adoption will require collaboration with the shipping industry to ensure data accessibility.
"The science shows that this approach works," Sheehan added. "So many ships now have real-time GPS, but if we want to implement this on a larger scale, we need to work closely with the shipping industry."
Research Report:Detection of Landslide-Generated Tsunami by Shipborne GNSS Precise Point Positioning
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