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Preface on a special issue for JUDGE project
Hirokazu Hase
1997
vol. 48 (3/4), p. 121.
JUDGE project: A continental scientific drilling into subduction zone. (1) Executive summary
Tetsuro Urabe, Nobuo Morita, Tsutomu Kiguchi, Teruki Miyazaki and Shin-ichi Kuramoto
1997
vol. 48 (3/4), p. 122-125, 2 tables.
Keywords: Japanese Islands, JUDGE Project, continental drilling, subduction, earthquake prediction
Abstract: The Japanese Islands locate at the plate boundary which is, geologicallyspeaking, one of the most active region on our globe. At this region, oceanic plate diagonally descends under continental plate. This phenomenon, called plate subduction, causes various kinds of natural hazards such as volcanic eruption, earthquake and tsunami. On the other hand, it gifts us variety of natural resources. For example, the gold, a representative mineral resource in Japan, contributed the fertility of the Japanese culture in ancient era: The treasures of Imperial Warehouse Shousoin and a large amount of scriptures of Buddhism which represent Tempyo Culture of the 8th Century were bartered with T'ang Dynasty, China for gold from Japan (Shiba, 1990). All the geological characteristics of Japanese Islands are derived from the subduction and relevant activities.
Japanese Ultra-deep Drilling and Geoscientific Experiments (JUDGE project) is a proposal of a big science project to conduct land-based drilling at southern Kanto region to intersect the subduction zone that exist at a depth of 10 km and to perform scientific observation with this well as if it is a telescope to look into the earth's interior. This special issue presents the societal and scientific rationale of the project as well as its summary, technical review of its feasibility, and required technology innovation.
Southern Kanto is a very rare locality where we can reach subduction zone from the surface at a depth less than 10 km. The area is also unique in the world since there is fully furnished seismometer network that enables us to monitor seismicity related to the subduction. In this subduction zone, we can observe geologic unit called accretionary prism in which sediments on the oceanic plate are rolled up as if they were scraped up by a bulldozer. The basement of the Japanese Islands has been accumulated throughout the geologic time as accretionary prism formed along the eastern margin of the Asian continent. The JUDGE project gives us an opportunity to observe active processes of "mountain building" and global geochemical cycle which occur in a major scale at the subduction zone. Therefore, the JUDGE well is regarded as a natural laboratory to test critical hypotheses on earth processes.
The JUDGE project is also able to answer questions of societal interest; JUDGE well is expected to penetrate through the earthquake source fault of giant inter-plate earthquake which did and will continue to attack Kanto area. In-situ monitoring at the fault gives us a chance to possibly contributes to the prediction of the giant inter-plate earthquake. The JUDGE project contributes to widen the option on geological disposal of high level radioactive waste for a country like Japan that locates in the subduction zone. Therefore, information obtained by the JUDGE project is not only indispensable for the security of Japanese nation but also useful for the circum pacific nations who suffer similar natural hazards.
The estimated temperature of the JUDGE hole at a depth of 10 km ranges between 200 and 400 degree C, according to the various methods of estimation. If we assume the highest value of 400 ° C as the bottom-hole temperature, maximum operation temperature of present drilling tools and mud should be raised by 110°C. Besides, a completely new concept of drilling operation should be developed to get as many data as possible. Therefore, it is essential, at an early stage of the program, to determine geothermal gradient accurately to set the goal of the technology development. The JUDGE project is based upon the systematic integration of technology which will give us strong incentives to expand the industrial horizon toward the unexplored domain like Apollo project.
JUDGE project: A continental scientific drilling into subduction zone. (2) Societal relevance of the JUDGE Project
Tetsuro Urabe, Nobuo Morita, Tsutomu Kiguchi, Teruki Miyazaki and Shin-ichi Kuramoto
1997
vol. 48 (3/4), p. 126-131, 1 fig., 1 table.
Keywords: Japanese Islands, JUDGE Project, continental drilling, subduction, earthquake prediction
Abstract: The JUDGE project is aimed to understand the earth's interior, last unexplored region of our planet earth, by conducting ultra-deep continental scientific drilling and multi-purpose scientific observation onto subduction zone. This project provides us with fundamental knowledge that is indispensable for; (1) reducing the damage of geologic hazard such as earthquake, (2) exploration for new energy resources, (3) managing deep ground-water and mineral resources, and (4) geologic disposal of radioactive or toxic waste. Besides, it will give incentive for innovation of new technology. The JUDGE well will intersect the earthquake source fault to enable us in-situ observation of generation mechanism of giant inter-plate earthquake which will unavoidably attack the Tokyo metropolitan area in the near future. It also gives us data indispensable for evaluating several options of safe disposal of high level radioactive waste. The aim of this special issue is to access the feasibility of the project through cooperative work between science and engineering. Geological Survey of Japan (GSJ) regards JUDGE project as an important big project in future from the scientific and societal view point. This is the reason why JUDGE Project Promotion Team was organized in 1995. GSJ also established a committee with National Research Institute for Earth Science and Disaster Prevention (NIED) to jointly promote the JUDGE Project.
JUDGE project: A continental scientific drilling into subduction zone. (3) Scientific rationale of the JUGE prodect
Tetsuro Urabe, Katsumi Kimura, Takashi Nakajima, Shin-ichi Kuramoto, Akira Takada, Kenji Satake, Koichiro Fujimoto, Naoto Takeno, Yoshito Nakashima and Nobuyuki Kaneko
1997
vol. 48 (3/4), p. 132-159, 20 figures, 1 table.
Keywords: JUDGE Project, subduction zone, accretional complex, circulation, inter-plate earthquake, hydrocarbon
Abstract: The most challenging topics in earth sciences include mechanism of sediment accretion, stress/strain distribution over decollement zone, deformation/metamorphism of plates and crusts, generation of inter-plate earthquake, genesis of hydrocarbon, and deep fluid circulation all occur in a major scale along the subduction zones. Most of the world's subducting zone is too deep to intersect by drilling from land-based drill sites, if we take the present level of the technology into account. However, there exists exception south of Tokyo metropolitan area where we can reach the upper surface of subducting Philippine Sea (PHS) Plate at a depth of 10 km. The JUDGE hole will penetrate through accretionary wedge and decollement zone before it reaches the PHS plate. The hole will also intersect seismic fault of devastating 1923 Kanto Earthquake and other giant inter-plate earthquakes. Many interesting questions arise about the nature and the role of the dehydrated fluid on the processes of deformation and earthquake generation. These questions can be answered through monitoring and observation using JUDGE hole since it is unparalleled by any other means in earth science.
JUDGE project: A continental scientific drilling into subduction zone. (4) Program plan of the JUDGE project
Teruki Miyazaki, Takanobu Yokokura and Tetsuro Urabe
1997
vol. 48 (3/4), p. 160-172.
Keywords: JUGE Project, site survey, geophysical exploration, pilot hole, KTB Project
Abstract: Execution plan of the JUDGE project is discussed and presented. Several steps are necessary before we start drilling of the main hole of the JUDGE project; that is, (1) site survey, (2) technology development, (3) drilling and down-hole monitoring of pilot holes, and (4) establishment of an archive for data and sample distribution. It is concluded that the organizational structure and decision-making process should be kept as flexible as possible until the completion of the pilot holes. This is because repeated evaluation and accessment of the results obtained through steps (1) to (3) should be reflected for the final site selection and technology development. Therefore, the program plan stated in this Chapter shoud be regarded as a possible design at the present level of knowledge.
JUDGE project: A continental scientific drilling into subduction zone. (5) Cooperation with ICDP
Ryuji Ikeda
1997
vol. 48 (3/4), p. 173-175, 1 fig.
Keywords: continental scienctific drilling, ICDP, international organization, Germany
Abstract: The International Continental Scientific Drilling Program (ICDP) was launched on 26th February 1996 among Germany, United States and China to foster international cooperation on continental scientific drilling. The ICDP will provide funds to help or fully support drilling related costs for projects which are recommended by Science Advisory Group and approved by Executive Committee. An important component of the ICDP is not only to help scientists from different countries to work together but also to encourage scientists to link their scientific results to help resolve problems that are of long term societal relevance. It is essential to join ICDP for the success of the JUDGE Project both from the viewpoints of science and engineering.
JUDGE project: A continental scientific drilling into subduction zone. (6) Scientific drilling hole assessments in JUDGE Project
Shin-ichi Kuramoto, Tetsuro Urabe, Tsutomu Kiguchi and Hiroaki Tsukahara
1997
vol. 48 (3/4), p. 176-185, 6 figs.
Keywords: terrigenous deposit, accretionary prism, pore water, dehydration reaction, temperature gradient, Curie point depth, devariatoric stress, rupture criterion
Abstract: According to the scientific purposes of the JUDGE drilling, geological and geophysical conditions of the hole are estimated and discussed. The general stratigraphy of JUDGE hole is estimated from the forearc crustal structure of Izu-Bonin arc and from the onland geology of Boso region. Fluid flow in accretionary prisms is reviewed and points out the possibility of over pressured fluid in the JUDGE hole that may obstruct the drilling. Bottom hole temperature is roughly estimated for the purpose of technological goal as 400 ℃ in maximum. Feasible estimation may be 200-400 ℃. However, there is no data of temperature just on the hole. Stress condition in drilling holes is reviewed in general. Borehole breakouts are concerned, but it is extremely hard to estimate before drilling because of the regional complexity of geological structure. Then pilot holes are highly recommended to take significant and fundamental data such temperature gradient and stress in JUDGE hole. Moreover, on-line monitoring tools while drilling are much eager to develop to scientific and safety drilling.
JUDGE project: A continental scientific drilling into subduction zone. (7) Technical development
Nobuo Morita, Seiji Saito, Sumio Sakuma, Wataru Takahashi, Chikao Yoshida, Morihiro Sano, Yoshinobu Jinzaki, Shigeru Nakayama and Hideaki Kakuma
1997
vol. 48 (3/4), p. 186-243, 59 figs., 30 tables.
Keywords: scientific drilling, KTB, Kola, borehole thermal simulation, mud water, logging, borehole monitoring
JUDGE project: A continental scientific drilling into subduction zone. (8) On archives of data and information of JUDGE
Teruki Miyazaki and Noriyuki Tomizawa
1997
vol. 48 (3/4), p. 244-252, 4 figs., 3 tables.
Keywords: well data, database, archive, JUDGE project
Abstract: In this paper we propose data types and design of the concept of archives which are appropriate for data handling of the JUDGE project. The archives consist of three layers and four subspaces: the three layers are the public, participant, and management layers, and the four subspaces are the data creation, data archive, data process, and data reference subspaces. Using this concept, we have built a pilot system and loaded it with well-log, core image and other data to evaluate the validity of data archive and management system. The pilot system consisting of a workstation and application softwares shows good performance in data inquiry and presentation. It is also confirmed that the system can manipulate information of existence and in/out of real materials of data.
JUDGE project: A continental scientific drilling into subduction zone. (9) Conclusion and terminology
Tetsuro Urabe, Nobuo Morita, Tsutomu Kiguchi, Teruki Miyazaki, Shin-ichiro Kuramoto and Koichiro Fujimoto
1997
vol. 48 (3/4), p. 253-256.
Keywords: JUDGE project, continental drilling, feasibility study
