Shallow Mexican seabed traps tsunamis so they strike land repeatedly

map of Mexico

One Mexican quake triggered an unusual tsunami

USGS

Tsunamis can keep pummelling the same patch of coast for days at a time if conditions are right. The finding means the initial big wave may not be the only source of danger, and authorities might need to rethink their evacuation responses following a tsunami alert.

On 8 September 2017 a deadly magnitude-8.2 earthquake struck Mexico – the first of two major tremors in the area that month. The quake caused a tsunami in the Pacific Ocean. It reached a maximum height of three metres when it hit the …