Challenges to drill through seismogenic zone

The deep sea riser drilling vessel, CHIKYU started its scientific operation from 2007 after completed the shakedown and training cruises. It is capable of riser drilling up to 7,000m deep below sea floor at 2,500 water depth and aims to the seismogenic zone and mantle in the future. CHIKYU explores the Earth interior as the first riser equipped scientific drilling platform of the Integrated Ocean Drilling Program, to contribute such important scientific program as the Nankai Trough Seismogenic Zone Experiment, the Deep Hot Biosphere, the Japan Trench Fast Drilling, and the Deep Coal bed Biosphere off Shimokita. Any of these expeditions involve technological and operational difficulties related to strong current, high wave, strong wind, deep water, and deep penetration. This paper describes some topics of technological challenges for these expeditions.