A powerful 7.0-magnitude earthquake struck the South Pacific Ocean on Monday, prompting a brief tsunami alert for Tonga. The United States Geological Survey (U.S.G.S) reported that the quake occurred about 49 miles southeast of Pangai, Tonga, at 1:18 a.m. local time.
Tsunami waves were possible for coastlines within 190 miles of the earthquake’s epicenter, including those on Tonga, according to preliminary reports from the U.S. Tsunami Warning System. However, an all-clear notice was issued about an hour later, after it was determined that no tsunami would occur.
Tsunamis are caused by large displacements of water in the ocean, usually resulting from earthquakes or landslides on or below the ocean floor. They can radiate in all directions and cause coastal flooding, powerful currents, and damage lasting for hours or days.
Following the earthquake, a smaller aftershock was detected in the region. Aftershocks are typically minor adjustments along a fault line that slipped during the initial earthquake. However, they can occur weeks, months, or even years after the first event and may be as large or larger than the initial quake.
Source: https://www.nytimes.com/interactive/2025/03/30/world/tonga-quake-tsunami.html