I am Yasuhiro, the logging specialist of this cruise. You may not know what logging is. This is a bit complicated story and I am going to tell you about it later on...

This is my second participation in Chikyu’s scientific drilling projects. The previous chance was her very first scientific drilling in 2007. We, the scientists and the ship crew, experienced many new things at that time because it was the first cruise. On board this time, I have felt everyone on the Chikyu is an expert in every field. A Japanese proverb, ‘feeling as if on a large ship’, can tell exactly how I felt as a sense of security and comfort. In fact, the Chikyu is a very large ship of almost 60,000 ton and extremely stable. When a typhoon hit the Chikyu in 2007, I even didn’t realize it because I was in a lab without a window to see outside. Surely we are always shaken a little bit, but I feel as if I were in a cradle and actually can sleep very well every night. The foods we can eat every 6 hours are always fresh and excellent, thus the on-board life is really comfortable.

I have been a company employee after my first degree in Geology. I wanted to know how the subjects I learned at the University are used in the real society. At a petroleum company as an exploration geologist to look for new oil and gas fields, I have found how earth science is useful for the society. Did you know the society is using earth science for exploration and development of energy and earth resources, because most of these are originally in the subsurface? I learned a lot from many specialists in the industry and gradually inclined to know more about earth science and use it to contribute to the society. This led me to my current status. With students, I am now polishing what I learned during my industry days, and conducting research to find out something new, and to apply that to something useful for the society. The participation on this cruise and contribution to such a state-of-the art science is very important for me to express my return to those who have been supporting me.

Now, I need to speak about logging. Original meaning of logging is to take log (record), but the log of this cruise means data. We dropped special sensors to the well we drilled, measured various data, and took underground water from subsurface rock. We call this operation ‘logging’. My task is to use the data to investigate the rocks in detail. This logging, as a measurement method, is commonly used in energy exploration industry, thus I am using my industry experience for this scientific drilling.

In the logging data acquisition unit. After a 12-hours measurement was completed successfully.

This expedition planned to take underground water from sub-sea rocks, but the million-year aged rocks are tough counterparts and didn’t allow our attempts easily. Several rocks became our targets after analysis on the logging data, then a special tool of water sampling went into the well. The rocks were however extremely soft and the fragments of rocks plugged the tool when we tried to squeeze water. We had to push and pull the rocks with the tool... Can you imagine that we had to have such a game with the underground rocks of the Pacific Ocean? After a long time of our persistent efforts, the rocks finally allowed us to take water. By analyzing this water, one more new side of the earth may be discovered.

Logging data analysis by nice guys of staff-scientists
(Sanada-san, Nakamura-san, Moe-san) and myself (from left to right).

Log also means tree trunk (Maruta in Japanese). You may have seen or heard ‘log-house’. There is a street named ‘Maruta-machi (Log town)’ in the south of the imperial palace, Kyoto. Where the street crosses the Kamogawa-river, we can see the landscape of the Kitayama (north hills), which is my favorite. I recall this landscape to refresh my brain, and listen in to the story of million-years ago that the data tells.

One of the logging tools is going into the well.