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A wide swath of ocean southeast of the Loyalty Islands revealed two distinct tsunami fronts moving across deep water within a single satellite pass.<\/p>\n
Tracing that signal, Jean H. M. Roger at Earth Sciences New Zealand<\/a> demonstrated that the structure matched a propagating tsunami rather than normal ocean motion.<\/p>\n One front appeared stronger and farther from the source, while a second, weaker front followed along the same path within minutes.<\/p>\n Because both fronts were recorded during a single overflight, the observation captured a continuous wavefield that invites deeper analysis of how tsunamis evolve in open ocean conditions.<\/p>\n Tsunami in 2D<\/p>\n Before this event, orbiting instruments usually cut across tsunamis as narrow lines, leaving scientists to reconstruct the broader shape afterward.<\/p>\n Unlike older satellites, Surface Water and Ocean Topography (SWOT<\/a>) satellites scan a broad strip, capturing both width and length.<\/p>\n Back in 2004, satellites<\/a> clearly recorded the Indian Ocean tsunami, but only along narrow crossing lines.<\/p>\n With side-to-side structure finally visible, researchers can separate real wave geometry from ordinary ocean bumps with far greater confidence.<\/p>\n How the tsunami began<\/p>\n At 2:57 a.m. UTC on May 19, 2023, a magnitude 7.7 earthquake<\/a> struck southeast of the Loyalty Islands.<\/p>\n Its shallow rupture shoved part of the seafloor upward, and that sudden lift pushed seawater above it into motion.<\/p>\n Soon afterward, coastal gauges and offshore sensors across the southwest Pacific began recording the disturbance as it moved away.<\/p>\n By the time SWOT arrived near 4:00 a.m. UTC, the expanding wave was already racing across deep water.<\/p>\n Cleaning the picture<\/p>\n Open-ocean<\/a> height data mix many signals, and a tsunami can hide inside normal swells, currents, tides, and eddies.<\/p>\n To strip that clutter away, the team compared the event with the previous day and data from seven other satellites.<\/p>\n Once those background patterns were removed, the northern front stood out clearly, while smaller secondary waves appeared inside the main ring.<\/p>\n Without that cleanup, ordinary ocean variability could easily masquerade as tsunami structure and blur the story the satellite captured.<\/p>\n Waves within waves<\/p>\n The image showed more than a single crest, because several shorter ripples trailed behind the larger leading front.<\/p>\n Those lagging ripples reflected dispersion, when different wavelengths travel at different speeds, so the tsunami stretched as it moved.<\/p>\n Near the strongest front, the wave<\/a> rose about 6 inches (15 centimeters) and extended for more than 62 miles (100 kilometers).<\/p>\n That direct look at a dispersing train gave scientists a rare view of behavior models have long predicted.<\/p>\n Model meets measurement<\/p>\n Computer simulations of the earthquake produced fronts in nearly the same places and at nearly the same times.<\/p>\n Using a simple rupture scenario, the model<\/a> matched the phase of the leading waves better than their size.<\/p>\n Measured heights still came out larger, with the mismatch averaging about 5 inches (13 centimeters) and reaching much more in places. Simulations consistently underestimated the observed wave amplitudes.<\/p>\n Why the fit slipped<\/p>\n Source estimates for this earthquake remain uncertain, partly because seismic coverage in that corner of the Pacific is sparse.<\/p>\n Even a small change in where the fault moved can alter how much water rises and where energy travels.<\/p>\n Another analysis<\/a> moved the source about 12 miles (19 kilometers) to better match the available regional records.<\/p>\n Below the wave, rugged bathymetry \u2013 the shape of the seafloor \u2013 likely added small reflections and bends the simple model missed.<\/p>\n What scientists gain<\/p>\n A two-dimensional record gives tsunami scientists something they almost never get: the full layout of the wave in motion.<\/p>\n That broader view helps test earthquake source ideas, because direction, curvature, and spacing all carry clues about what happened below.<\/p>\n Earlier satellite passes could confirm timing or height, but they left most side-to-side structure inferred.<\/p>\n The conclusion highlights that two-dimensional data allows scientists to better separate tsunami waves from background ocean signals.<\/p>\n Rare but revealing<\/p>\n Catching any tsunami from orbit still depends on luck, because satellites and fast waves rarely meet at the right moment.<\/p>\n During SWOT\u2019s early daily-repeat phase, that unlikely alignment happened, and the spacecraft crossed the signal in about four minutes.<\/p>\n After calibration, the mission moved to a 21-day repeat orbit, making similar encounters even harder to expect.<\/p>\n That rarity limits warning use, but it makes each successful overflight a powerful test of how tsunamis really behave.<\/p>\n Future tsunami research<\/p>\n The new map ties earthquake motion, deep-ocean travel, trailing ripples, and model error into one scene scientists could not see before.<\/p>\n With better source estimates and more wide-strip missions, rare flyovers could become one of the sharpest checks on tsunami physics and risk.<\/p>\n The study is published in Natural Hazards and Earth System Sciences<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read?\u00a0Subscribe to our newsletter<\/a>\u00a0for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on\u00a0EarthSnap<\/a>, a free app brought to you by\u00a0Eric Ralls<\/a>\u00a0and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Researchers have documented the first two-dimensional map of a tsunami moving across the open ocean, captured by a…\n","protected":false},"author":2,"featured_media":385732,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[85,46,141],"class_list":{"0":"post-385731","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-il","9":"tag-israel","10":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/385731","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/comments?post=385731"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/385731\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media\/385732"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media?parent=385731"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/categories?post=385731"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/tags?post=385731"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}