Geologists use earthquake waves to reveal anomalies deep under Pacific

Huge areas of rock appear to be remains of submerged plates, despite being far from plate boundaries

What is going on underneath the Pacific Ocean? Scientists have discovered huge chunks of rock that look like the remains of submerged plates in the deep mantle underneath the western Pacific Ocean. Is there a lost world down there?

Researchers used all the different types of earthquake waves to build a high-resolution model of the Earth's interior. The model, published in Nature Scientific Reports, has revealed a number of anomalous regions in the deep mantle, including a huge area under the western Pacific Ocean where seismic waves travel slower than average. Traditionally slow seismic waves have been interpreted as areas of cold tectonic plate material, recycled into the mantle over the past 200m years. However, this location is far from plate boundaries, with no geological evidence of subduction.