Behemoth is the only word that comes to mind as I discuss, with mouth agape, about the deep-sea drilling vessel Chikyu. JAMSTEC, the Japanese Agency for Marine-Earth Science and Technology, launched a venture in 2005 to take the deepest cores into the earth’s crust following the route of Nautilus in Jules Verne’s novel. The deepest core into the crust was currently 2111m but during the Center for Deep Earth Exploration (CDEX) the goal was 7000m. To accomplish this…the Japanese unleash Chikyu which translates into “earth”, a fitting name given the size of the ship. Yes it is really that big…it is hide-the-children-and-flee-for-the-country-side big. The vessel is 210m long (689ft), approximately 20 school buses in length. The gross tonnage on this monster is 57,500 tons, approximately the weight of 460 blue whales. I realize that vessels do get larger. The QE II has length of 963ft and gross tonnage of closer to 70,000 tons. However, as research vessels it is ginormous. Plus the QE II cannot drill 7000m into the earth’s crust in 4000m of water.
This week Chikyu completed a successful first expedition to one of the most active earthquake fault zones on the planet where 4 boreholes 1000’s of meters deep were drilled. Ultimately, sensors will be installed in the boreholes to monitor physical stresses, movement, temperature and pressure. The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is the first geologic study of the underwater subduction zone faults that give rise to the massive earthquakes known as mega-thrust earthquakes. Scientists will presented their findings from the first expedition at the American Geophysical Union meeting this previous week n San Francisco.
“If we want to understand the physics of how the faults really work, we have to go to those faults in the ocean,” he explains. “But earthquakes don’t happen at the surface; they happen literally miles down beneath the surface along these active faults.” With the deep-drilling capabilities afforded by the Chikyu the team was able to reach the seismogenic zones for the first time. “No one’s been able to make observations inside an active fault like this,” Tobin says. “The drilling is unique because it allows us access to where the faults actually are, where the earthquakes actually happen.”