A bstract new ray‐tracing method called linear traveltime interpolation (LTI) is proposed. This computes traveltimes and raypaths in a 2D velocity structure more rapidly accurately than other conventional methods. The LTI formulated for cell model, calculations of are carried out only on boundaries. Therefore raypath considered to be always straight with uniform velocity. approach suitable tomography analysis. algorithm consists two separate steps: step 1 calculates all boundaries; 2 traces...

To detect the change of physical properties in small areas, a series high‐resolution waveform inversions is applied to time‐lapse seismic data. A procedure by use differentiation between data and normalization using reference proposed this study. The derived as straight‐forward extension inversion scatterer imaging. Through numerical tests, approach was found be more accurate than conventional obtaining velocity areas. method crosswell obtained during Mallik 2002 gas production test. area...

The METI (Ministry of Economics, Trade and Industry) Sado-oki Nansei 3D seismic survey was carried out in deep water southwest off Sado Island, Japan Sea. area covered the Umitaka Spur, which features mounds pockmarks. Other surveys sampled large masses methane hydrate beneath sea floor, discovered bubble plumes rising into water, investigated high resistivity anomalies below floor. We applied pre-stack time migration continuous velocity analysis method to data, geological P-wave structure...

The vertical cable seismic is one of the reflection methods. It uses hydrophone arrays vertically moored from seafloor to record acoustic waves generated by surface, deep-towed or ocean bottom sources. Analyzing reflections sub-seabed, we could look into subsurface structure. Because VCS an efficient high-resolution 3D survey method for a spatially-bounded area, proposed it hydrothermal deposit tool development program Japanese government. Our first experiment surveys has been carried out in...

Summary The VCS survey is one of the reflection seismic methods. It uses hydrophone arrays vertically moored from seafloor to record acoustic waves generated by sources. Because an efficient high-resolution 3D method for a spatially-bounded area, we proposed it SMS tool development program started Japanese government. In 2010, manufactured autonomous data acquisition systems. Through several experimental surveys, our successfully completed. 2011 and 2013, have carried out surveys using GI...

Summary The Cabinet Office, Government Japan started the Cross-ministerial Strategic Innovation Promotion Program (SIP) in which “Next-generation technology for ocean resources exploration” is scheduled from 2014 to 2018. J-MARES (Research and Development Partnership Next Generation Technology of Marine Resources Survey) a private partnership participating this SIP program organized four companies (JAPEX, JGI, NSENGI MMTEC). Since 2014, 6 research cruises have been carried out by J-MARES,...

Gas hydrates are located in the permafrost and deepwater shallow sediments, where low temperature high pressure satisfy stability conditions of methane clathrates to remain as solid compounds. Hydrates found a form fine-layered or altered-layered structure with hiatuses necessitate high-resolution surveys, which may not be achieved by conventional marine acquisition using towed streamers. We have developed recent case study vertical cable seismic (VCS) method has been used for subseafloor...

Conversational gestures have a crucial role in realizing natural interactions with virtual agents and robots. Data-driven approaches, such as deep learning machine learning, are promising constructing the gesture generation model, which automatically provides motion for speech or spoken texts. This study experimentally analyzes learning-based model from text using convolutional neural network. The proposed takes sequence of words input outputs 2D joint coordinates representing conversational...

The Vertical Cable Seismic (VCS) is one of the reflection seismic methods. It uses hydrophone arrays vertically moored from seafloor to record acoustic waves generated by sea surface, deep-towed or ocean bottom sources. This method useful delineate detailed structures in a spatially-limited area below seabed deep where conventional methods are not effective. Since 2009, we have been successfully developing an integrated VSC system with financial support Japanese Government technology...

The deep-towed Autonomous Cable Seismic (ACS) system is a high-resolution acoustic survey designed for use in deep-water environments. This uses high-frequency source and multichannel receiver cable. A common problem the analysis of ACS data unstable positioning receivers due to ocean currents seafloor bathymetry. Since acquisition using with source–receiver positions causes destructive interference on final stack profile, correction source-receiver crucial issue. In this study, we propose...

In SIP project "Next-generation technology for ocean resources exploration", we have been developing "Integrated Survey System" concealed SMS exploration. this approach, seismic survey is one of key technologies to investigate subsurface structure with high resolution. The Multi-Stage Seismic our proposed reflection methods deposits. This investigation method consists VCS (Vertical Cable Seismic), ACS (Autonomous Seismic) and ZVCS (Zero-offset Vertical Seismic). already published, but a...

Summary Full Waveform Inversion (FWI) of seismic data is a high resolution subsurface imaging tool and there lot effort to fully industrialize it. The method, which uses gradient based fitting approach minimize the misfit between observed simulated waveforms, strongly requires either good initial model or low frequency for convergence global solution. In this paper, we address cycle skipping phenomena when none two above mentioned requirements are met. Then suggest method extracting from...

This study tested autonomous control of multiple AUVs using two hovering at a depth 80 to 90 m water area in Lake Biwa by implementing AUV-AUV communication and positioning. The tests were successfully conducted with navigating autonomously 1) formation, 2) holding both ends the horizontal cable, 3) approaching an underwater acoustic lighthouse, while minimizing information commands from mother vessel.

Summary The Cabinet Office, Government Japan started “Next-generation technology for ocean resources exploration” project as one of Cross-ministerial Strategic Innovation Promotion Program (SIP). In this project, the exploration target is seafloor massive sulphide (SMS), especially buried deposits. Very high resolution images are required in seismic survey. We introduce new concept data acquisition vicinity bottom using autonomous recording systems, order to preserve frequencies and achieve...

In 2014, Japanese Government starts "Next-generation technology for ocean resources exploration" program, one of the issues "Cross-Ministerial Strategic Innovation Promotion Program (SIP)" to accelerate these research and development sensing technology, sampling method environmental impact assessment, so on. We proposed "Multi-staged Integrated approach SMS Exploration" it has been accepted it. Our integrated (MSI) approach" includes Vertical Cable Seismic (VCS) survey technique EM as well...

We have fabricated an underwater vibratory seismic source with the scale of 60-70 %, to real design for towed marine vibrator (MSV) using hydraulic servo system. Several evaluation tests were conducted in sea downsized MSV at a depth about 250m water. The performance was tested maximum sound level, frequency characteristic, horizontal directivity, and vertical directivity field generated from Suruga Bay 100 km away Tokyo. level characteristic equal or higher than estimated specification...

Abstract. A high frequency deep‐tow seismic survey was carried out in the Nankai Trough area 1996. The objective of to obtain resolution sections and velocity profiles methane hydrate zone, inferred from strong BSR events seen on conventional data area. special feature is that both source streamer cable are towed close seabed. This acquisition geometry requires processing handle varying receiver depths. CMP floating datum sequence designed which led quality shallow geology. key step devising...

Marine wide-angle seismic data obtained using air guns and ocean-bottom seismographs (OBSs) are effective for determining large-scale subseafloor velocities, but they ineffective imaging details of shallow reflection structures because poor illumination. Surface-related multiple reflections offer the potential to enlarge OBS illumination area. We have developed a new method surveys applying interferometry, technique that uses surface-related multiples similarly mirror imaging. Seismic...

Summary In this paper we examine the application of Equivalent Offset Migration (EOM) to Vertical Cable Seismic (VCS) survey data extract subsurface velocity model. We present our method applying EOM VCS and results from processing two datasets. find be a useful tool in extracting model data. The is motivated by difficulty conventional analysis techniques CMP gathers formed have very low fold making difficult. allows output high-fold Common Scatter Point (CSP) data, which can usefully...

A high frequency deep-tow seismic survey was carried out in the Nankai Trough area 1996. The objective of to obtain resolution sections and velocity profiles methane hydrate zone, inferred from strong BSR events seen on conventional data. special feature is that both source streamer cable are towed close seabed. This acquisition geometry requires data processing handle varying receiver depths. CMP floating datum sequence designed which led quality shallow geology. key step devising a...

Abstract We developed a towed marine seismic vibrator (MSV) as new type source that employed the hydraulic servo system for controllability both in phase and amplitude of signal being emitted. MSV could mitigate risk impact to environment while satisfying necessary condition sources enable shear wave analysis improve situation data acquisition. conducted sea trial acquire reflection using downsized streamer cable above seafloor where cabled observatory has been deployed. A series controlled...

Summary Vertical Cable Seismic (VCS) is a reflection seismic survey method, which uses hydrophone arrays vertically moored from the seafloor to record acoustic waves generated by sources. It useful for obtaining high fidelity image over shallow, narrowly bounded areas, such as potential hydrothermal deposits. However, irregular geometry including variation in receiver depth, and large differences depth between sources receivers presents challenges processing VCS data. We have successfully...

日本周辺海域では,海底熱水鉱床やコバルトリッチクラスト,マンガン団塊といった海洋鉱物資源が発見されてきた。著者らは,深海の海洋鉱物資源探査を目的とした新たな調査ツールの開発や効率的な探査システムの検討を行ってきた。2018年には未調査の熱水活動域を対象とした統合調査が実施された。本論文では掘削サンプリングを含む統合調査の一環として実施した深海曳航型ハイドロフォンケーブルを用いた音波探査によって取得した,高分解能海底下イメージについて述べる。本システムの空間分解能(水平および垂直)はメートルオーダーである。音波探査記録から熱水の流路となる断層や裂かといった断裂構造を特定しその分布を示した。また,掘削調査結果と照らし合わせることによって,過去に熱水性硫化鉱物が堆積していた層準を特定した。本研究の調査海域は表層堆積物中の裂かの分布から現在も断層活動が継続していると考えられるが,海底面に断層の存在を示唆する地形は認められなかった。また,本海域は堆積速度の早い環境であることが示唆された。よって,調査海域は硫化鉱物を堆積させる熱水活動はあるが早い堆積速度によって大規模な熱水鉱床へ発達しにくい...

Abstract In the Seafloor Massive Sulfide (SMS) exploration, buried sulfide deposits without hydrothermal activity are important for mining development. We had proposed Vertical Cable Seismic (VCS) exploration of SMS and found out it could reveal deposit through surveys. The conventional VCS data processing gave us large-scale 3D structure. re-examined to focus on very shallow part so that detailed structure be recognized. adopted Three-dimensional Pre-Stack Depth Migration (3D-PSDM) method...

A new method was developed to estimate the geomagnetic transfer functions on basis of Sompi spectral analysis which gives higher frequency resolution than conventional techniques.We extended from one dimensional time series three quantities and applied it variation data. With this technique, we can up longer periods techniques same length It is also possible describe source field polarization in variations. This enables us according direction.