Beneath the Hawaiian Islands lies a colossal, iron-rich 'mega-blob' of solid rock, a new study reveals. This mega-blob, known as a mega-ultralow velocity zone (ULVZ), may be the key to understanding the Hawaii hotspot, an area of intense volcanic activity. Doyeon Kim, a seismologist at Imperial College London, explains that the blob's iron-rich composition enhances thermal conduction, potentially prolonging the hotspot's activity. ULVZs are massive regions near the mantle-core boundary, about 1,800 miles below the Earth's surface, where seismic waves slow dramatically. These zones are often found near volcanic hotspots like Hawaii, Iceland, and the Marquesas Islands. Kim and his team used a novel method combining compressional and shear waves to study the mega-ULVZ under Hawaii, ruling out a hypothesis suggesting an extra-melty composition. This discovery provides insights into the blob's origin, possibly linked to Earth's early evolution or subduction of water-rich oceanic crust. The study also highlights the importance of understanding Earth's processes to comprehend planetary formation. This research, published in Science Advances, opens new avenues for understanding the dynamics of ULVZs worldwide.
