Tsunami experts theorize that shock waves produced after a massive underwater volcanic eruption near Tonga on Jan. 15 caused the higher tidal levels seen along Japan's Pacific coastline.

Tsunamis and tidal waves have a lot in common. Both are powerful ocean surges that can cause death and destruction. While that remains true, tsunamis and tidal waves differ in major ways ...

During an emergency news conference early Jan. 16, the agency said the latest tidal surge was quite different from a typical tsunami generated by an offshore earthquake, noting that water levels ...

After Supertyphoon Haiyan hit the Philippines, even key leaders were swept up in the tsunami-like storm surge. The WSJ's Ramy Inocencio speaks with a national Cabinet minister, the Tacloban mayor ...