Megathrust earthquakes

The raggedness of the ocean floors could be the key to triggering some of the Earth's most powerful earthquakes, scientists from Cardiff University have discovered. In a new study published today the team, also from Utrecht University, suggest that large bumps and mounds on the sea floor could be the trigger point that causes the crust in the Earth's oceans to drastically slip beneath the crust on the continent and generate a giant earthquake. By studying exposed rocks from a 180-million-year-old extinct fault zone in New Zealand, the researchers have shown, for the first time, that the extremely thick oceanic and continental tectonic plates can slide against each other without causing much bother, but when irregularities on the sea floor are introduced, it can cause a sudden slip of the tectonic plate and trigger a giant earthquake. The researchers believe that this information, along with detailed subsurface maps of the ocean floor, could help to develop accurate models to forecast where large earthquakes are likely to occur along subduction zones, and therefore help to prepare for disasters. For generations scientists have known that the largest earthquakes, known as megathrust earthquakes, are triggered at subduction zones where a single tectonic plate is pulled underneath another one. It is also in these regions that volcanoes form, as is most common in the so-called 'Ring of Fire' in the Pacific Ocean - the most seismically active region in the world. The most recent megathrust earthquake occurred in Tohoku, Japan in 2011.