The NASA-CNES Surface Water and Ocean Topography satellite, or SWOT, has revealed that its satellite observations reveal the early stages of a tsunami's impact on the event, following a magnitude 8.8 earthquake in 2025, which triggered a tsunami that spread across the Pacific Ocean. The findings may help improve understanding of future tsunamis and earthquakes at subduction zones, particularly near the ocean trench where two tectonic plates meet and one slides beneath the other. The SWOT satellite made its observations within 70 minutes of the earthquake's start and observed a distinct pattern of smaller waves trailing behind it, which had previously been predicted in computer models and theoretical studies. The study also found that when earthquake-caused movement extends close to the trench, it can generate shorter waves that travel more slowly and spread out over time, forming a trailing pattern behind the main tsunami front. The strength of these trailing waves increases when earthquake movement extends closer to the surface, suggesting these waves are linked to where and how the tsunami was generated near the trench. This knowledge could help improve models used to evaluate tsunami hazards and make coastal communities more resilient.