To image and characterize the lunar subsurface, we have developed an active seismic exploration system that combines a single ultra-compact seismic source with a single geophone. The seismic source employs a voice-coil actuator, a type of linear electromagnetic motor, which minimizes the source mass while maintaining a nearly constant force of 10 N over a wide frequency range. Despite its compact size of less than 800 g, the source can emit seismic signals repeatedly. Stacking the repeated signals enhances the signal-to-noise ratio, allowing both body-wave and surface-wave propagation over source-receiver distances exceeding 60 m, as demonstrated in field tests at Mount Fuji. When the seismic source is operated at multiple locations around a fixed geophone, astronauts or rovers can acquire multichannel-equivalent seismic datasets. This configuration enables retrieval of 2D or 3D S-wave velocity profiles to depths of 7 m through surface-wave analysis. In contrast, when both the seismic source and the geophone are mounted on separate rovers and moved independently, the system allows flexible multi-shot and multi-receiver acquisition geometries. This configuration enables body-wave-based seismic refraction and reflection surveys, allowing refraction tomography to derive 2D P-wave velocity models and reflection analysis to image subsurface structures to depths of 80 m. Finally, we optimized these systems and adapted them for space applications, enabling deployment by astronauts and integration with rovers in future space missions. (c) 2026 The Author(s). Published by Elsevier B.V. on behalf of COSPAR. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).

We have developed a portable active seismic source (PASS) to monitor CO2 storage reservoirs at a depth of approximately 1 km. Despite its small size, stacking the signals generated by the PASS improves the signal-to-noise ratio of the seismometer data far from the source. The smaller size and lower cost of the PASS enables its permanent deployment in many locations to continuously monitor CO2 storage reservoirs. To achieve continuous monitoring, distributed acoustic sensing (DAS) is also a vital technology. Based on DAS, we can continuously record the signal from the PASS in an extensive area, including within boreholes and offshore fields. Here we report application of the PASS for the borehole DAS system. We confirmed the PASS signal propagation to a depth of similar to 1 km when we used a PASS with 630N at 50 Hz close to the wellhead and recorded the signal by the borehole fiber optic cable. The ability of the system to propagate the PASS signal to a depth of similar to 1 km enables continuous monitoring of most CO2 storage reservoirs with high temporal resolution. Furthermore, deploying multiple PASS systems could improve the spatial resolution of monitoring results. (c) 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

高分解能三次元地震探査（3D-HRS）の実証試験を，大分県別府湾の浅海域において実施した。GIガン（150立方インチ）と6本のショートストリーマーケーブルを曳航し，高密度観測システムとリアルタイム測位システムを用いて空間分解能の高い地震探査記録を取得した。構成された観測システムは軽量で，小型船舶からのケーブルの展開と揚収が容易であり，浅海域における効率的なデータ取得を実現した。3D-HRSデータ処理では，ノイズ抑制やフットプリント抑制など入念な反射法データ処理により高精細なイメージングが行われた。中でも，重合前のノイズ除去，ゴースト除去，多重反射波除去，およびフットプリントの除去が反射断面の品質を向上させるために重要な役割を果たした。既存の二次元地震探査断面と比較して，小規模な断層群をより詳細に可視化できており，既往成果の解像度をはるかに上回った。さらに，3D-HRSマイグレーションボリュームから，SimilarityおよびThinned Fault Likelihoodなどのサイスミックアトリビュートを算出し，断裂・断層などの地下構造の空間不連続性を効果的に抽出することができた。別府湾の実証試験結果から，3D-HRSシステムは海底面形状および海底下に潜在する小規模な断層や旧河道などを高解像度で可視化し，活断層系の断層ネットワークを詳細に把握できる能力を示した。

海底熱水鉱床やレアアース泥といった有用金属濃集帯は海洋鉱物資源としての利用が期待されている。反射法地震探査によって海底下の構造を把握することは,海洋鉱物資源の空間的な分布を把握するために重要な役割を果たす。海底下構造のイメージング分解能は振源周波数とデータ密度に左右される。従って,高周波振源を用い,海底近傍で稠密にデータ取得を行うことで対象物のスケールに見合った高分解能データの取得が可能となる。

PreviousNext No AccessProceedings of the 14th SEGJ International Symposium, Online, 18–21 October 2021High-resolution 3D marine seismic acquisition and imaging in shallow waters: Application to shallow fault detection, Beppu-Bay, JapanAuthors: Yosuke TeranishiFumitoshi MurakamiShinji KawasakiMotonori HigashinakaKei KonnoHitoshi TsukaharaTakeshi KozawaShigeru InoSusumu AbeKeiji TakemuraShinji OhsawaYosuke TeranishiJGI, Inc.Search for more papers by this author, Fumitoshi MurakamiJGI, Inc.Search for more papers by this author, Shinji KawasakiJGI, Inc.Search for more papers by this author, Motonori HigashinakaJGI, Inc.Search for more papers by this author, Kei KonnoJGI, Inc.Search for more papers by this author, Hitoshi TsukaharaJGI, Inc.Search for more papers by this author, Takeshi KozawaJGI, Inc.Search for more papers by this author, Shigeru InoJGI, Inc.Search for more papers by this author, Susumu AbeJGI, Inc.Search for more papers by this author, Keiji TakemuraKyoto UniversitySearch for more papers by this author, and Shinji OhsawaKyoto UniversitySearch for more papers by this authorhttps://doi.org/10.1190/segj2021-053.1 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract A high-resolution 3D (HR3D) seismic survey was conducted to clearly reveal and map faults and fractures in a shallow-water region of Beppu-Bay, Japan, where is a pull-apart-basin developed with right-lateral strike-slip fault activities. The HR3D seismic survey was conducted using a dense array of 6-short streamers combined with a single GI-gun (150 cu.in.). The system configuration can provide excellent illumination of geological features, even in shallow waters which is hard to image accurately with traditional methods. This system realizes high cost-efficient acquisition, which is light in weight, easy to deploy and retrieve cables from a small vessel. It is also capable of acquiring high resolution data. In the HR3D seismic processing sequence, pre-stack noise attenuation, de-ghost, de-multiple, and acquisition footprints removal played an essential role to enhance seismic imaging quality. Then, the seismic data were processed into a post-stack time-migrated 3D volume. Compared to existing 2D seismic sections, the resolution achieved with the HR3D seismic was much higher. Furthermore, the HR3D migrated volume allowed to delineate highly detailed features of seafloor and subsurface. Following the seismic processing sequence, similarity and thinned fault likelihood (TFL) attribute workflows were used to detect and visualize faults and fractures within the HR3D migrated volume. The workflows revealed a network of broadly distributed faults and fractures along an active fault system in Beppu-Bay. Keywords: high-resolution seismic, shallow waters, seismic processing, seismic fault attributePermalink: https://doi.org/10.1190/segj2021-053.1FiguresReferencesRelatedDetails Proceedings of the 14th SEGJ International Symposium, Online, 18–21 October 2021ISSN (online):2159-6832Copyright: 2021 Pages: 349 publication data© 2021 Published in electronic format with permission by the Society of Exploration Geophysicists of JapanPublisher:Society of Exploration GeophysicistsSociety of Exploration Geophysicists of Japan HistoryPublished Online: 29 Nov 2021 CITATION INFORMATION Yosuke Teranishi, Fumitoshi Murakami, Shinji Kawasaki, Motonori Higashinaka, Kei Konno, Hitoshi Tsukahara, Takeshi Kozawa, Shigeru Ino, Susumu Abe, Keiji Takemura, and Shinji Ohsawa, (2021), "High-resolution 3D marine seismic acquisition and imaging in shallow waters: Application to shallow fault detection, Beppu-Bay, Japan," SEG Global Meeting Abstracts : 198-201. https://doi.org/10.1190/segj2021-053.1 Plain-Language Summary Keywordshigh-resolution seismicshallow watersseismic processingseismic fault attributePDF DownloadLoading ...

PreviousNext No AccessSEG Technical Program Expanded Abstracts 2020Simple theory for processing reflection seismic data from moving offshore vibratory sourceAuthors: Hiroaki OzasaEiichi AsakawaFumitoshi MurakamiJunichi TakekawaHitoshi MikadaHiroaki OzasaIHI CorporationSearch for more papers by this author, Eiichi AsakawaJGI CorporationSearch for more papers by this author, Fumitoshi MurakamiJGI CorporationSearch for more papers by this author, Junichi TakekawaJGI CorporationSearch for more papers by this author, and Hitoshi MikadaJGI CorporationSearch for more papers by this authorhttps://doi.org/10.1190/segam2020-3425982.1 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail AbstractWe propose a new processing approach not only to correct but to exploit the effects of the motion of marine vibratory source deployed an offshore seismic survey. We decompose the survey data into plural sections as a function of time, space and signal frequency. The instantaneous spatial locations of shot/receivers as a function of time and signal frequency are used in the data processing. Our processing method is applied to numerical simulation data for a moving source generating a waveform of a finite time duration encoded with a frequency sweep, and to a marine seismic reflection survey data acquired by a mechanical-driven marine seismic vibrator that was designed to verify its feasibility. We found it is possible to remove the source motion effect by applying our processing approach with the conventional migration processing. Furthermore, we perceived the enhancement of the lateral resolution after taking the motion of the source into account in marine vibrator survey. The utilization of marine vibratory sources has the potential to realize high accuracy survey when exploiting the continuity in time and space for seismic emission.Presentation Date: Tuesday, October 13, 2020Session Start Time: 9:20 AMPresentation Time: 10:10 AMLocation: Poster Station 6Presentation Type: PosterKeywords: marine, vibroseis, signal processing, Kirchhoff, resolutionPermalink: https://doi.org/10.1190/segam2020-3425982.1FiguresReferencesRelatedDetails SEG Technical Program Expanded Abstracts 2020ISSN (print):1052-3812 ISSN (online):1949-4645Copyright: 2020 Pages: 3887 publication data© 2020 Published in electronic format with permission by the Society of Exploration GeophysicistsPublisher:Society of Exploration Geophysicists HistoryPublished Online: 30 Sep 2020 CITATION INFORMATION Hiroaki Ozasa, Eiichi Asakawa, Fumitoshi Murakami, Junichi Takekawa, and Hitoshi Mikada, (2020), "Simple theory for processing reflection seismic data from moving offshore vibratory source," SEG Technical Program Expanded Abstracts : 3013-3017. https://doi.org/10.1190/segam2020-3425982.1 Plain-Language Summary Keywordsmarinevibroseissignal processingKirchhoffresolutionPDF DownloadLoading ...

Abstract We have developed deeply-towed mechanical driven marine seismic vibrator (MSV) for the use in time-lapse seismic reflection survey to monitor offshore hydrocarbon reservoirs, in which interstitial fluids move with the production, for the optimization of recovery. For this objective, we evaluate the survey performance using MSV and revisited the data processing. A downsized MSV was manufactured to conduct a sea trial to evaluate the performance as a seismic source in a real 2D seismic line survey off the coast of the Japan Sea. We compare the processed results (a) for the data acquired by a downsized MSV and (b) for that acquired by a 480 cu-inch airgun array. We then tried to improve the data processing for data acquired by the downsized MSV that was towed at a water depth which any conventional airgun could not be fired to see if the signal-to-noise ratio is improved. We verified the survey performance using deeply-towed MSV and our data processing approach could be equivalent to it of airgun array the maximum seismic emission power of which is about 40 dB larger than that of the downsized MSV. Downsized MSV which was towed 50 m below the sea surface could acquire a conventional 2D seismic survey data with a conventional streamer cable. The superposition of long-leg surface multiples was observed in the data acquired by deeply towed MSV as anticipated. Our MSV showed the high stability in the source signature over the entire survey period, which is favorable for the use in time-lapse surveys. We also confirmed that the surface multiples could be suppressed in the processing we have introduced to exploit the utilization of multichannel signal processing to improve the SNR of acquired data. Moreover, we noticed that the surface multiples removed in the processing may also be used as signal to be superimposed with the processing data to enhance further the SNR. Since the MSV does not sacrifice the power of signal generation against the towing depth and generated signal has high repeatability, the combination of deeply-towed MSV and our processing method could realize precise time-lapse survey which keeps the quality of survey data without large-volume amplitude.

We conducted a marine seismic reflection survey using both an airgun array and a marine seismic vibrator (MSV) designed to be towed in water. The maximum power of seismic emission of the airgun array was about 40 dB larger than that of the MSV. The same survey line was traced twice for comparing the performance of the two different seismic sources. The sweep length of MSV was set to 4 seconds and the towing depth was set to 50 m below the surface. We compare the result of our processing approach optimized for the MSV survey with the result processed by conventional processing and the result acquired by conventional airgun array. After that, we evaluate the survey performance of deep-towed MSV processed by our approach. We found our processing approach based on multichannel processing could improve the survey performance of deep-towed marine vibrator to the same level as airgun beyond the difference of the power of seismic emission. This method could realize efficient marine vibrator survey which keeps the quality of survey data without large-volume amplitude. Presentation Date: Tuesday, September 17, 2019 Session Start Time: 8:30 AM Presentation Time: 10:35 AM Location: 221A Presentation Type: Oral

Multi-stage high-resolution seismic survey system has been developed to explore Seafloor Massive Sulfides (SMS) deposits. The authors demonstrated the feasibility of this system around offshore west Kume Island, Okinawa Trough. In the first stage, a deep-towed streamer (ACS; Autonomous Cable Seismic) was used at the survey area about tens of square kilometers. After the ACS, a ZVCS (Zero-offset Vertical Cable Seismic) survey was carried out in a more limited area within several square kilometers. A vertical hydrophone array is one of the key components of ZVCS in order to suppress noises caused by side reflections. The conventional VSP data processing techniques such as wave field separation and stacking can be applied to the data obtained by this system. Subsequently, 3DVCS (Three-Dimensional Vertical Cable Seismic) was deployed to obtain a 3D image of subsurface structures with high-resolution. Result of ACS survey gave us an opportunity to interpret characteristic seismic facies around the hydrothermally active area. High quality seismic sections acquired by ZVCS made it possible to image the complex shallow structures. The 3D seismic volume after pre-stack depth migration using 3DVCS data made us capable of interpreting three dimensional structures and tracking the key reflectors of SMS.t.

PreviousNext No AccessProceedings of the 13th SEGJ International Symposium, Tokyo, Japan, 12–14 November 2018Area Extraction for Hydrothermal Deposits using Multi-Stage Seismic Survey SystemAuthors: Shutaro SaitoEiichi AsakawaFumitoshi MurakamiHitoshi TsukaharaKenji TaraSangkyun LeeMasafumi KatouShutaro SaitoJ-MARES / JGI, Inc.Search for more papers by this author, Eiichi AsakawaJ-MARES / JGI, Inc.Search for more papers by this author, Fumitoshi MurakamiJ-MARES / JGI, Inc.Search for more papers by this author, Hitoshi TsukaharaJ-MARES / JGI, Inc.Search for more papers by this author, Kenji TaraJ-MARES / JGI, Inc.Search for more papers by this author, Sangkyun LeeJ-MARES / JGI, Inc.Search for more papers by this author, and Masafumi KatouJ-MARES / JGI, Inc.Search for more papers by this authorhttps://doi.org/10.1190/SEGJ2018-003.1 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract Multi-stage seismic survey system has been developed to delineate Seafloor Massive Sulfides (SMS) deposits. The authors demonstrated the feasibility of this system around offshore west Kume Island, Okinawa Trough. In the first stage, a deep-towed streamer (ACS; Autonomous Cable Seismic) was used at the survey area about tens of square kilometers. After the ACS, a ZVCS (Zero-offset Vertical Cable Seismic) survey was carried out in a more limited area within several square kilometers. A vertical hydrophone array is one of the key components of ZVCS in order to suppress noises caused by side reflections. The conventional VSP data processing techniques such as wave field separation and stacking can be applied to the data obtained by this system. Subsequently, 3DVCS (Three-Dimensional Vertical Cable Seismic) was deployed to obtain a 3D image of subsurface structures with high-resolution. Result of ACS survey gave us an opportunity to interpret characteristic seismic facies around the hydrothermally active area. High quality seismic sections acquired by ZVCS made it possible to image the complex shallow structures. The 3D seismic volume after pre-stack depth migration using 3DVCS data made us capable of interpreting three dimensional structures and tracking the key reflectors of SMS. Keywords: ACS, ZVCS, 3DVCS, SMS, shallow sub-seafloor high-resolution imagingPermalink: https://doi.org/10.1190/SEGJ2018-003.1FiguresReferencesRelatedDetails Proceedings of the 13th SEGJ International Symposium, Tokyo, Japan, 12–14 November 2018ISSN (online):2159-6832Copyright: 2019 Pages: 588 publication data© 2018 Published in electronic format with permission by the Society of Exploration Geophysicists of JapanPublisher:Society of Exploration GeophysicistsSociety of Exploration Geophysicists of Japan HistoryPublished Online: 29 Apr 2019 CITATION INFORMATION Shutaro Saito, Eiichi Asakawa, Fumitoshi Murakami, Hitoshi Tsukahara, Kenji Tara, Sangkyun Lee, and Masafumi Katou, (2019), "Area Extraction for Hydrothermal Deposits using Multi-Stage Seismic Survey System," SEG Global Meeting Abstracts : 7-10. https://doi.org/10.1190/SEGJ2018-003.1 Plain-Language Summary KeywordsACSZVCS3DVCSSMSshallow sub-seafloor high-resolution imagingPDF DownloadLoading ...

Imaging deep structures using land seismic data acquired in complex terrains of Japan often faces since the geology is often complex and target is usually deep volcanic. Recently, acquisition of long-offset high density data using combination of cable and cable-free systems in complex terrain is standardized in domestic land acquisition. First Arrival Travel-Time Tomography is applied to such data to estimate subsurface velocity structure where conventional velocity analysis is difficult because of the above problems, and recently FWI is applied following tomography to estimate detailed velocity structure. low frequency sensors high We will show some case study of data acquisition using those techniques. The result is verified by comparing with legacy data. In addition to data acquisition techniques, we have applied some data processing techniques which are not used in legacy data. The processing techniques include combination of noise removal techniques, surface consistent deconvolution, accurate velocity estimation and pre-stack imaging. Also we have applied some broad band techniques such as geophone response correction and spectral whitening using wavelet transform. By combined effect of those recently developed techniques, our result show great improvement compared to legacy data.

We propose an innovative approach to achieve the high signal to noise ratio(SNR) of offshore seismic survey data and to reduce the environmental impact in the offshore, deploying a marine seismic vibrator (MSV) as an artificial active source. The combination of interferometric approach for both source and receiver locations could increase the number of virtual shots and receivers and allows the application of conventional CMP-gather based processing even to data generated by virtual sources with the interferometric approach. We applied our method to sea trial survey data that was conducted to confirm the performance of MSV and found out that processed CMP-stack data has higher resolution than that without interferometric processing. The utilization of MSV has proven out concept that the combination of marine environmental-friendly seismic source and the interferometric approach could become a method of data acquisition without airgun without sacrificing the signal-to-noise ratio of seismic survey. Our study also indicates that the signal-to-noise ratio of seismic data could even by enhanced with the inclusion of interferometric processing to produce data from virtual sources. Presentation Date: Tuesday, October 16, 2018 Start Time: 1:50:00 PM Location: Poster Station 20 Presentation Type: Poster

We propose a novel approach to realize the practical offshore shear wave exploration without any contact of seismic source to seafloor by employing a marine vibratory source and interferometric approach. We conducted scaled experiments and a sea trial, and confirmed that the dipole sound source could enhance the reflected shear waves from the subsurface, and interferometric approach could reduce the number of ocean bottom sensors required to conduct the seismic survey. Presentation Date: Tuesday, September 26, 2017 Start Time: 3:05 PM Location: 370A Presentation Type: ORAL