How does a tsunami form and how fast does it travel across the ocean?

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1. 1

   Tsunami (Wikipedia)

   WikipediaPublished Oct 16, 2026Checked Oct 17, 2026

   “A tsunami ( (t)soo-NAH-mee, (t)suu-; from Japanese: 津波, lit. 'harbour wave', pronounced [tsɯnami]) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions, underwater explosions, landslides, glacier calvings, meteorite impacts and other disturbances above or below water all have the potential to generate a tsunami. Unlike normal ocean waves, which are generated by wind, or tides, which are in turn generated by the gravitational pull of the Moon and the Sun, a tsunami is generated by the displacement of water from a large event. Tsunami waves do not resemble normal undersea currents or sea waves because their wavelength is far longer. Rather than appearing as a breaking wave, a tsunami may instead initially resemble a rapidly rising tide. For this reason, it is often referred to as a tidal wave, although this usage is not favoured by the scientific community because it might give the false impression of a causal relationship between tides and tsunamis.”

2. 2

   Tsunami modelling over global oceans.

   Royal Society open science (Kolukula et al.)Published Jan 15, 2025Checked Oct 17, 2026

   “The aftermath of the 2004 Indian Ocean tsunami led to the establishment of the Indian Tsunami Early Warning System (ITEWS). Predicting real-time tsunami heights and the resulting coastal inundation is crucial in ITEWS to safeguard the coastal communities. Global tsunamis other than those in the Indian Ocean might weaken at Indian coasts due to distance yet still cause significant damage due to local coastal morphological amplification. The current study focuses on tsunami simulations over global oceans. A finite element (FE)-based ADvanced CIRCulation (ADCIRC) model is configured to the global domain to model global tsunamis accurately and efficiently. The model mesh has a spatial resolution of 2 km in the shallow waters and relaxed to 20 km in the deeper waters. Model simulations are performed for significant historical events, assessing their effect on near and far field regions. Computed results are compared with the observations, and it is found that the model's predictions align well with the observations. The simulation results demonstrate that ADCIRC can be applied to real-time tsunami predictions due to its computational efficiency and accuracy.”

3. 3

   Delayed submarine caldera subsidence creates extreme tsunami hazard.

   Science advances (Cronin et al.)Published Sep 2, 2026Checked Oct 17, 2026

   “The 2022 Hunga volcano eruption generated one of the largest and most destructive volcanic tsunamis ever recorded. We interpret the timing, nature and relative hazard of volcanic-tsunamigenic processes by combining geophysical, oceanographic, atmospheric, and eye-witness observations of this event. Hydro-acoustic signal (T waves) detected on seismic stations up to 2600 km away provided a key to discerning tsunami triggers from explosions, volcanic mass flows, and caldera subsidence. The largest tsunami was generated by the first of at least two sudden caldera-subsidence events. This occurred 1 hour after globally detected explosions that produced smaller tsunami. Our results provide rare insights into the rates of caldera subsidence and highlight the complex multiple sources of tsunamis resulting from eruptions of oceanic volcanoes.”

4. 4

   Seismoacoustic monitoring of eastern mediterranean earthquakes toward a tsunami early warning system for Egypt.

   Scientific reports (Elbehiri et al.)Published Oct 23, 2025Checked Oct 17, 2026

   “The decision matrix (DM) was applied to the different magnitude types to validate the accuracy of magnitude values in the first alert. Results indicated that tsunami warnings based on M[Formula: see text] (Mwp) were more accurate than those derived from M[Formula: see text] (mB). The M[Formula: see text] (Mwp) produced 87.5% accurate alerts in 11 minutes compared to 84.4% in 6 minutes. Considering tsunami travel times for the analyzed earthquakes, 11 minutes would be sufficient time for the implementation of tsunami countermeasures in Egypt. Additionally, infrasound waves generated by these earthquakes in the Mediterranean Sea were detected over vast distances from the epicenter. Frequency-wavenumber (F-K) analysis of infrasound waves could contribute to earthquake location verification. Infrasound wave propagation is among the most critical factors affecting infrasound recordings. Therefore, for using infrasound technology for detecting future disasters, a comprehensive understanding of wave propagation is crucial for optimizing infrasound data acquisition and applications, especially with constructing local infrasound observatories in Egypt for monitoring.”

5. 5

   Pacific tsunami records suggest similar rupture locations of two great Kamchatka earthquakes only 73 years apart.

   Science advances (Carvajal et al.)Published Sep 23, 2026Checked Oct 17, 2026

   “Whether seismic slip can far exceed the slip budget of a subduction megathrust over a short time has important implications to earthquake physics and hazards. The first modern test comes from two great Kamchatka earthquakes of moment magnitude 8.8 to 9.0 in 1952 and 2025. Here, we use tide gauge tsunami records across the Pacific to determine whether the two events ruptured the same or complementary fault areas. We extract records of the 1952 tsunami from analog marigrams at 52 tide gauge stations and minimize their time uncertainties by matching hindcast tides. The 1952 tsunami waveforms and travel times are remarkably similar to those of the 2025 event. Tsunami modeling shows that a range of relative rupture locations can produce the waveform similarity, but only nearly colocated ruptures can explain the travel time similarity. On the basis of conventional rationale, the 2025 earthquake consumed more than twice the megathrust slip deficit accrued since 1952. We explain the conundrum by fast energy accumulation in a viscoelastic Earth.”