One of the most extreme underwater events known as submarine slides is the megaslide. The sixth-largest recorded megaslide occurred in the Surveyor Fan in the Gulf of Alaska around 1.2 million years ago. This megaslide covered an area of at least 16,124 square kilometers and had a preserved volume of 9,080 cubic kilometers. These massive underwater events can have significant impacts on the seafloor and can translate into tsunamis on the surface.
A recent study published in Geophysical Research Letters by Sean Gulick and colleagues delved deeper into the Surveyor Fan megaslide. By using images from seismic reflection surveys and ground truth data from drilling efforts in the Gulf of Alaska, researchers were able to uncover the existence of the megaslide and study the seafloor topography before and after it occurred. The researchers identified the factors that led to the megaslide, including the Mid-Pleistocene Transition (MPT).
Between 0.6 and 1.2 million years ago, the Mid-Pleistocene Transition (MPT) took place. During this period, the glacial-interglacial cycle began growing longer. The researchers suggest that sediment buildup and flux during the MPT, caused by extensive ice cover, led to slope instability. This instability, combined with seismic activity, likely triggered the megaslide in the Surveyor Fan.
After the occurrence of the Surveyor Fan megaslide, the researchers noted a decrease in megaslides of the same magnitude. This change can be attributed to various factors, including a shift in the balance between sediment flux and seismic strengthening. Additionally, ice streams crossing the continental shelf spread sediment deposits over large areas on the continental slope, resulting in less cohesive slides. The buildup of sediment along the Alaska margin also played a role in reducing the likelihood of slope failure.
The study on the Surveyor Fan megaslide sheds light on the mechanisms behind underwater landslides and their potential to trigger tsunamis. Understanding these events is crucial for predicting and mitigating the impacts of submarine landslides on coastal areas. Further research in this field will help scientists develop better strategies for managing the risks associated with underwater landslides and tsunamis.
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