'Every 90 seconds for 9 days': Scientists trace mysterious 2023 global tremors to Greenland mega-tsunami

Scientists have finally solved the mystery behind two strange events that shook the entire planet for nine days straight. Seismic monitoring stations across the world, in September 2023, detected unusual tremors that occurred every 90 seconds for these nine consecutive days. These signals carried the characteristics of earthquakes but they lacked any obvious geological source. No tectonic movement, volcanic activity, or meteor impact could explain the rhythmic global shaking. A similar pattern of tremors returned again just a month later, deepening the mystery. These unprecedented seismic activities had long puzzled scientists until recent satellite data provide clarity.

Scientists eventually traced the potential origin to East Greenland’s remote Dickson Fjord which unleashed a 650-foot high mega-tsunami. Satellite imagery and local data suggested that two large landslides had occurred in this region. The cause of these landslides has been attributed to the collapse of permafrost and glacial structures likely a result of rising Arctic temperatures. However, there is no direct evidence of abnormal wave activity available at the time.

Researchers proposed that the landslides had generated mega-tsunamis that were trapped in the fjord, thus creating standing waves known as seiches. These seiches resulted from approximately 25 million cubic meters of rock and ice crashing into the fjord. The confinement of these seiches within the steep walls of the fjord could have produced the regular ground vibrations detected globally. But without direct observation, the theory sill remained unconfirmed.

The mystery was solved using data from the SWOT (Surface Water and Ocean Topography) satellite, which was launched by NASA and France’s CNES. The SWOT, equipped with the Ka-band Radar Interferometer (KaRIn), could measure water surface height in narrow areas like fjords with 2.5-metre resolution. Unlike the previous satellites, it was able to detect subtle vertical movements in the fjord’s surface.

The SWOT satellite data revealed that he land on either side of the fjord was shifting in opposite directions, consistent with a standing wave. Cross-channel slopes with height differences of up to two metres were identified. These opposing movements confirmed the presence of a seiche. These waves had rebounded within the fjord for nine days, producing the rhythmic seismic pulses recorded around the globe.

The impact of these landslides generated waves reached heights of 200 metres. Researchers estimate the energy generated by the seiches was about 500 gigawatts, which is equivalent to the simultaneous launch of 14 Saturn V rockets. This study highlights the increasing risks posed by melting glaciers and permafrost in polar regions.