Chikyu Report
Back to Expedition

Better Luck This TimeJuly 16, 2012

Everyone was elated and relieved when the temperature observatory was successfully installed on Monday evening, completing one of the main objectives of JFAST. In about a week's time of Expedition 343T ('T' for technical) we were able to drill the borehole to 855 meters below seafloor and install the temperature sensors across the plate boundary - something that we could not accomplish in over 50 days of operation a few months ago.

"Everything in life is luck"
Donald Trump "In my experience, there's no such thing as luck"
Obi-Wan Kenobi, in Star Wars by George Lucas.

There are many steps in the deployment of the observatory, such as preparation of the underwater camera system, running the long pipe to the ocean floor, setting the wellhead, borehole re-entries, underwater instrument releases, borehole drilling, casing installation, temperature instrument programming. During the original expedition last April and May, it seemed at almost every step of the way there was some problem or delay. Also there were many concerns about operations in nearly 7000 meters of water, for which Chikyu and other IODP platforms had no experience. This time in July, things were quite different and each procedure went surprisingly smoothly. The reasons are better weather, gained technical experience from the previous attempts, and a lot of good luck.

"Luck can only get you so far"
Hermione Granger, in Harry Potter and the Half-Blood Prince by J. K. Rowling. "The winds and waves are always on the side of the ablest navigators"
Edward Gibbon

Experience helps. Detailed knowledge of the actual drilling conditions and instrument performance, which are gained from experience, contribute immensely to success. Actually, CDEX engineers know this and told me so last year. At the time, they felt that all the technical challenges of the project could be met, it was just a matter of how many tries it would take and if there was enough time. We were very fortunate on this project that additional expedition days were provided so that we had the opportunity to try again. Also, it is a great credit to the drilling engineers and planning staff at CDEX that they were able to solve the many problems. Finally, luck often swings the balance between failure and success and we got lucky this time (I am getting more superstitious for these kinds of things).

"Those who have succeeded at anything and don't mention luck are kidding themselves"
Larry King

The deployment of the temperature sensors has been an exciting technical accomplishment, but the real scientific results come when we see the recorded data. The next challenge will be in several months when we try to extract the instrument string from the borehole, using a remotely operated vehicle (ROV) in the very deep water. These data should help us understand the huge amount of slip that occurred in the 2011 Tohoku earthquake.

Release of the instrument string from the drill pipe, which was the final step of the temperature observatory installation at 18:15 on July 16 (photo by Patrick Fulton).

More photos from the expedition at

▲Back to TOP

Drilling through the Japan Earthquake faultJuly 13, 2012

Drilling began out here on the JFAST2 expedition after successfully reentering the wellhead on the seafloor 6926 meters below the ship on the edge of the Japan Trench. The goal: to drill ~850 m below the seafloor across the plate boundary and through the fault that slipped more than 50 m at this location during the March 2011 Tohoku earthquake causing the enormous tsunami. We will then try installing a temperature observatory down into the hole to measure the remaining frictional heat across the fault.

Instead of using the standard top-drive drilling system on the ship to rotate the entire drill stem and create the torque on the drill bit 7 - 8 km below, as in the previous drilling at the site, this time we used a mud-motor located just above the bit to create the torque at the bit. The mud-motor causes rotation of the bit from pumping drilling mud (in our case the mud is actually sea-water) through the motor and out of the jets at the bit (see video above). Drilling with the mud motor has been incredibly effective and we quickly reached our target depth. We could see from the drilling parameters measured on board that when we started to drill through a hard chert we had previously encountered, confirming that we had successfully crossed the plate boundary fault and well into the down-going Pacific Plate.

The great water depth here is much deeper than conventional wells, and the total depth drilled for the observatory joins our other holes as part of JFAST project in being the deepest below the sea ever drilled for scientific ocean drilling. Our TD (total depth), as shown by the driller’s console in the picture below: 7780.81 meters below the ship’s rig floor!

Lastly, here I am in the picture below, happy for the great depth we were able to obtain. The depth of this deep borehole will provide space for us to install the observatory that will include temperature sensors that straddle the fault zone.

Next, the hole will be cleaned out and the all the drill pipe returned to the surface. We can then start assembling the observatory and lowering it down to the seafloor for the final, most difficult task of carefully installing it all the way down into the hole.

▲Back to TOP

Wellhead reentry deep within the Japan Trench ? like threading a needle 7 km awayJuly 12, 2012

The goal we are working towards on the JFAST2 expedition is to install an observatory of temperature sensors across the fault zone that slipped more than 50 m during the March 2011 Tohoku Earthquake. The temperature sensors will allow us to measure the frictional heat and determine the strength of the fault. To accomplish a critical step of the installation, we must first find the wellhead we installed last May on the seafloor 7 km below the ship, reenter it with the drill bit, and then drill down ~850 m through the plate boundary fault.

The only way we are able to reenter the wellhead on the seafloor, which will allow us to install the observatory into hole after drilling across the fault, is by finding it with an underwater television camera system (UWTV), slowly moving the 8.5 inch drill bit above the 20 inch opening, and then lowering to pipe down into it. An added challenge is that only way to move the drill bit towards and above and well head opening is slowly moving the ship a few meters at a time and then waiting for the 7 km long string of drill pipe to swing beneath us.

Once we were positioned above the GPS location of the wellhead, we slowly lowered pipe down the nearly 7 km below our drilling ship, Chikyu, one 40 m stand at a time. We then attached the UWTV around the drill pipe and lowered it down (see photograph) to just above the drill bit. Last May, the stress of raising and lowering the fiberoptic cable connecting the UWTV to the ship in such deep water created some damage to the cable, and prevented us from seeing anything or installing the observatory. Now, at the start of this expedition, the cable was repaired and we attempted using it at depth again for the first time.

It was a long, tense night in the Doghouse (the small enclosure on the rig floor shown in the photograph) trying to find and position ourselves above the wellhead and wondering whether the UWTV would work okay. Luckily things went well, we found the wellhead with the help of the cameras and a small sonar device on the UWTV, and successfully reentered the hole.

The next critical step is to recover the UWTV, and then drill about 850 m through the fault zone and into the subducting plate below...

▲Back to TOP

Return to the Japan Trench ? JFAST 2July 9, 2012

Greetings from the scientific deep sea drilling vessel Chikyu and the second part of the Japan Trench Fast Drilling Project: JFAST2 - IODP Expedition 343T. The focus of the JFAST project has been to quickly drill into and study the fault that slipped more than 50 m at shallow depths during the March 2011 M9.0 Tohoku Earthquake and caused the devastating tsunami.

In April and May, we (an international team of ~30 shipboard scientists along with a number of engineers, ship/drilling crew, and onshore support) successfully drilled across the plate boundary fault at ~820 m (0.5 miles) below the seafloor in water depth nearly 7 km (4.3 miles) deep. This ended up being the deepest below sea level any scientific ocean drilling project has ever gone. We actually did it twice! - the first time we used logging tools to map the geology as we drilled allowing us to pinpoint the fault, we then drilled another hole and collected spectacular core samples through the fault zone. The analysis of the rocks and data are already providing important insight into the mechanics of large earthquakes and tsunamis and will undoubtedly continue to be fruitful for many years to come.

Now I have returned to Chikyu to help undertake the other main goal of the JFAST project, to install a subsurface observatory that will measure the frictional heat signal remaining from the Tohoku earthquake. By measuring the extra heat across the fault at depth we can back out how much frictional resistance the fault had during the earthquake and possibly gain insight into why it slipped more than 50 m at our study location.

Together with the other JFAST analyses this unique and important data will not only help us understand the fault and earthquake here, but may also help us understand the potential hazards at other large faults like the Cascadia subduction zone fault off the Pacific Northwest of the United States and British Columbia, Canada.

During the first JFAST expedition, we had many technical problems associated with trying to drill in such deep water for the first time and many delays from weather that prevented us from installing an observatory in the time window we had. We now have been fortunate enough to be given the opportunity to return for one last try.

After flying on board Chikyu by helicopter and transiting North for a couple days, we are now on site and starting to lower pipe down to the seafloor. We plan to then drill across the plate boundary fault once again and then install our observatory of subsurface temperature sensors in the remaining hole. There are many unique challenges with installing such an observatory and with drilling in such deep water depths, but we are all ready and excited to try our best on this difficult mission so we can continue to learn as much as we can from the devastating Tohoku earthquake.

Stay tuned . . . more to come shortly.

▲Back to TOP

Preparing for coreMay 16, 2012

The expedition is now gearing up to retrieve core samples from the interval of rocks that surround the plate boundary fault surface at the Japan Trench. Core samples will be retrieved from an approximately 200m long interval at a depth of almost 8km below sea level. These will become some of the deepest core samples retrieved by the Scientific Ocean Drilling Program. The coring process is like sticking a straw into a bowl of Jello, and then pulling up the bit of Jello stuck in the middle (the rock core). To think of the process at a scale comparable to the drilling operations here, however, you would have to imagine standing on the roof of the Empire State Building with a straw that extends down to street level.

To retrieve the core, about 8 km of drill pipe are assembled and lowered from the rig floor to the sea floor. The pipe has a drill bit attached at the tip that has a hollow center, where the core sample is preserved. The drill bit will advance through the rock until a ~10m interval has been sampled. This core remains in the core barrel inside the drill pipe until it is brought back to the surface by a wire line.

< There are many different types of drill bits for coring. Here is the kind that we are now using for the Chikyu drilling. The hollow tube in the center is where the core is preserved >

Once the cores arrive on deck, the samples will be measured, catalogued, cut into 1.5m sections, and split in half lengthwise. The core is described visually for sedimentologic, mineralogic, and structural components, as well as drilling induced damage. Samples are taken from the core to determine the physical and chemical properties of the rocks, and for study of microbiologic activity. Many of these samples will be analyzed in ship-board laboratories for properties that include electrical resistivity, porosity, moisture content, chemistry of pore waters, paleomagnetism, Hydrogen and Methane content, and thermal conductivity. Many additional samples will be sent back with the scientists to their respective labs for continued experiments and analyses after the cruise.

All the core sampling tools were laid out on the work bench as the scientists were trained in sampling methods

Small flags are placed to mark the location in the core where samples are taken. Each flag has a code for the type of sample

Analysis of the core requires the expertise of a wide range of scientists and laboratory technicians. All of the core data will be logged in IODP reports that become publicly available (you can see past reports at These data will provide invaluable information about the physical properties of the rocks in and around the fault zone and the processes that lead to the occurrence of large magnitude earthquakes.

▲Back to TOP

高校生との船上ライブ授業!May 12, 2012


















▲Back to TOP

「生命は地震から生まれた!」仮説に挑むMay 11, 2012

<その1 「ちきゅう」に紛れ込んだワタクシ>

*本レポートは、Webナショジオにて連載中の「青春を深海に賭けて」 からの転載です。






またWebナショジオのサイトでも、ついに「ちきゅうつぶやき編集長」による掘削調査航海の現場レポ企画が始まったようですね( 深海7000メートル! 東日本大震災の震源断層掘削をミタ! )。第53次南極観測隊員、渡辺佑基さんと田邊優貴子さんによる「南極なう!」のように臨場感溢れるナショジオらしい透明感のあるレポートと勘違いして、みなさんがうっかりクリックすることを大いに期待しています(笑)。














<その2 「生命は地震から生まれた!」仮説に挑む>





























▲Back to TOP

On the wayMay 8, 2012

After we reached the new world record of scientific ocean drilling depth on 25th April, an unexpected technical trouble occurred on 6th May. The drilling pipe was broken in the C0019C hole near the wellhead and we lost a part of the borehole assembly, including the LWD and MWD tools. This news came more or less as a big shock for all of us. It seems the operating plan we made after thorough consideration last week is also broken.

Fig. 1. The ocean surface seems peaceful, but the drilling operation under the extremely deep (~7000 m) water is full of risks. Photo by Tao Yang.

Even though disappointed, we need to calm down and take rapid response to this terrible setback. In the first 24 hours following the occurrence of the trouble, co-chiefs and EPM did very impressive works for the rearrangement of our operating plan. A detailed new schedule, including the risk assessment, was provided and discussed seriously by all science party members in the afternoon meeting on 7th May. Finally, we came to the consensus that even though this plan is risky, we are still going to carry it, considering both the chances of coring and deployment of MTL observatory are remained. We chose it also because even if we meet another technical trouble, the coring will still be on the table and we would still be able to get samples from the deep. This choice is a fortune for science, since we still remain the very precious opportunity to know the frictional temperature anomaly of the large amount slip of the 2011 Tohoku earthquake.

Fig. 2. The white board after the afternoon meeting on 7th May; this brief form, drawn by EPM Sean Toczko, saw our intense discussion about the contingency plan. A lot of things, which we hope are good, will happen in the next three weeks.

I gradually realize that it is the best time to test our group when we meet troubles and difficulties. It is the best time for us to display our strong resolution and recollected decision when we face setbacks. It is the best time for us to be cheered by our scientific willingness and remain positive and hopeful when the thing is not going smoothly. This time, I really feel the strong power supporting the entire group. I believe this power comes from all of us and will carry us to the success of the expedition.

Science is always on the way, and so are us. There might be failures on this way, but we will never give up trying to know the truth and we will never lose our science dream. Any steps on this way, no matter happiness or sadness, will be enjoyed by us. When we look back to this way in the future, we will appreciate all the efforts we made.

Best wishes for JFAST!

▲Back to TOP

Hard workMay 5, 2012

Last week we made headlines around the world when Chikyu’s drill string reached a new record length for ocean scientific drilling: a total of 7768.5 m measured from the rig floor (7740 m below sea level). OK, maybe “headlines” is stretching it but within the scientific drilling community, this was big news! Credit for this record goes to the hard work and ingenuity of the engineers, drillers and crew of D/V Chikyu. Here in the scientists’ library, we were celebrating their achievement by getting to work on the Logging-While-Drilling data that were collected. This was the first look at the fault we came to study, and the first indication of what kind of rocks we would encounter, and the first test of borehole stability in this deep environment.

New drill bit is assembled to the drill pipe on the rig floor. Photo by Tadashi Yoshizawa.

We poured over the data as it came in ? low resolution in real-time, and after the hole was complete and the instruments were back on board. The logging engineers downloaded the data from the instrument memory ? detailed images of the borehole walls, and long wiggly lines which showed the sediment and rock properties. For me, a field geologist, it was my first time seeing this type of data. I tried to imagine what the rocks would look like in an outcrop, or feel like in my hand, and what small features I could see with my hand lens if I had a sample to examine. There were some clues which the logging scientists helped me learn how to read in the data: fracture patterns, the subtle traces of sedimentary bedding. Most exciting were the points in the data which showed big changes in rock type down the hole: the transition from silica-rich sediments to a layer of clay, for example. I hope soon we will recover some core and I will get to find out if my imagined samples are anything like the real thing.

One of the old assumptions we are testing on this mission is whether the deep water sediments that make up the hanging wall of a subduction thrust fault are very soft and weak (and just get pushed around by earthquake slip in the stronger rocks at deeper depths in the fault) or whether they are strong enough to release some elastic energy themselves. We won’t be able to answer this until we have the sediment samples in hand, sometime in a week or two. But in case you’re wondering, this is what 856m of drilling will do to a new drill bit:

After the drilling, damage to the microdiamond-bearing drill teeth.
This probably happened when drilling through hard chert! Photo by Tadashi Yoshizawa.

▲Back to TOP

ターゲットを見つけろ!May 1, 2012

この航海が始まって一月近く経過しましたが、ようやく嬉しいニュースをお届けすることができます。4月24日未明から開始された掘削同時検層(LWD)は順調に進み、4月25日夜半までに目標とする地層を(たぶん)貫通!海底下856mで掘削を完了し、本航海2回目のチャレンジとなる深海掘削は、なんとか無事成功しました。そして、この掘削孔で海洋科学掘削における掘削パイプ長の世界記録(7768.5 m、海面からだと7740m!)まで樹立しました。

私は、この航海では、海底下の地層の特徴を物理データとして計測する掘削同時検層(LWD)の専門家として、またそのデータを用いた分析によりミッションを成功に導くため、科学者サイドと掘削や計測専門会社の技術サイドとの橋渡し役としてプロジェクトに参加しています。50m もスリップした大断層を直接探ろうというのは世界初、そして7000mの深海底から1000m近く掘り進めるのも世界初の試みです。

ここで、この掘削孔で導入した「掘削同時検層」という技術について少し解説しておきましょう。掘削同時検層(英語ではLogging-While-Drilling [LWD]といいます)とは、文字通り、ドリルで掘りながら同時に検層(地層の計測)を行う手法です。各種計測センサー、バッテリー、発電機などが内蔵された直径約20cm、全長約30mの細長いハイテク機器群をドリルビットの直上に連結して深海底まで降ろし、掘削しながら孔の壁を計測します。











Hole C0019Bでの掘削を完了し、




▲Back to TOP

1  2  3