Forearc density structure of the overriding plate in the northern area of the giant 1960 Valdivia earthquake

The objective of this work is to analyse the density structure of the continental forearc in the northern segment of the 1960 Mw 9.6 Valdivia earthquake. Regional 2D and local 3D density models have been obtained from available gravity data in the area, complemented by new gravimetric stations. Models are constrained by independent geophysical and geological information and new TEM and MT soundings. The results show a segmentation of the continental wedge along and perpendicular to the margin, highlighting a high-density anomaly, below the onshore forearc basin, that limits the late Paleozoic–early Mesozoic metamorphic basement in the region where Chaitenia terrane has been proposed. A progressive landward shift of this anomaly correlates with the high slip patch of the giant 1960 Mw 9.6 Valdivia earthquake. Based on these results, we propose that the horizontal extension of the less rigid basement units conforming the marine wedge and Coastal Cordillera domain could modify the process of stress loading during the interseismic periods, and also that changes in position and extension of the late Paleozoic–early Mesozoic accretionary complex could be linked with the frictional properties of the interplate boundary. This analysis provides new evidence of the role of the overriding plate structure in the seismotectonic process in subduction zones.

Geological Museum Innovations to Dealing with Covid-19 Pandemic | Inovasi Museum Geologi dalam Menghadapi Pandemi Covid-19

Bandung Geological Museum as the thematic earth museum in Indonesia has been established on 16 May 1929. This museum has 417,882 collections, there are mineral and rock collections, vertebrate, invertebrate, paleobotanical fossils, and artifacts. As a government museum, the Geological Museum has a duty to disseminating geological information. This article aims to identify the Geological Museum’s activities during the Covid-19 pandemic. After the temporary closure in March 2020, the museum activities were carried out virtually, including Collection Talk, Day and Night at the Museum, virtual tours, Bincang Museum, virtual geoscience socialization, and introduce the collections by social media. Museum Geologi Bandung sebagai museum kebumian di Indonesia telah berdiri sejak 16 Mei 1929. Museum ini memiliki 417.882 koleksi, berupa koleksi mineral dan batuan, fosil vertebrata, fosil invertebrata, fosil paleobotani dan artefak. Sebagai instansi yang bertugas menyebarluaskan informasi kegelogian, dimasa pandemi Covid-19, Museum Geologi berinovasi melakukan kegiatan-kegiatan edukasi dalam bentuk virtual. Tujuan penulisan artikel ini adalah melakukan identifikasi kegiatan dilakukan Museum Geologi selama pandemi Covid-19. Pasca penutupan sementara Museum Geologi pada bulan Maret 2020, kegiatan yang dilakukan berupa kegiatan virtual diantaranya: Collection Talk, Day and Night at the Museum, virtual tour, Bincang Museum, sosialisasi kebumian secara virtual, dan pengenalan koleksi melalui sosial media.

Surveying Tasks Solution Automation in the Framework of Mining and Geological Information System Creation at PJSC "Uralkali"

The results of work on the automation of the solution of engineering problems facing the specialists of mine surveying services of the mines of PJSC "Uralkali" are presented. The developed software modules are fully integrated into the corporate mining and geological information system of PJSC "Uralkali" and are grouped into specialized software systems - automated workstations. These complexes are installed at the workplaces of various mining specialists, from the heads of technical departments to employees of departments at mines. In total, 21 software systems were developed, of which three workstations were created for the specialists of the company's mine surveying service. For the mine surveying departments at the mines, an automated workstation "Local mine surveyor" was developed and put into commercial operation, for the department of capital surveying and geodetic works - an automated workstation "Capital mine surveying", for employees of the department of the chief mine surveyor of PJSC "Uralkali" - an automated workstation "Chief surveyor". The software modules that are part of the automated workstations of the specialists of the mine surveying service allow in an automated mode to solve a wide range of engineering problems, due to the requirements of the current regulatory documents. Among them, one can single out such tasks as: processing the results of instrumental survey of underground and surface objects and, on its basis, replenishment of mining and graphic documentation in digital form (2D and 3D); mining planning and design; preparation, editing and printing of standard technical documentation (payroll, tables, reports and graphics); solving issues of safe mining; analysis of the implementation of planned and design indicators of the mining enterprise, etc.

Reflection imaging of complex geology in crystalline environment using virtual-source seismology: case study from the Kylylahti polymetallic mine, Finland

For the first time, we apply a full-scale 3D seismic virtual-source survey (VSS) for the purpose of near-mine mineral exploration. The data was acquired directly above the Kylylahti underground mine in Finland. Recorded ambient noise (AN) data is characterized using power-spectral density (PSD) and beamforming. Data has most energy at frequencies 25–90 Hz and arrivals with velocities higher than 4 km/s have wide range of azimuths. Based on the PSD and beamforming results, we created 10-days subset of AN recordings that were dominated by multi-azimuth high-velocity arrivals. We use illumination-diagnosis technique and location procedure to show that the AN recordings associated with high apparent velocities are related to body-wave events. Next, we produce 994 virtual-source gathers by applying seismic-interferometry processing by cross-correlating AN at all receivers resulting in full 3D VSS. We apply standard 3D time-domain reflection seismic data processing and imaging using both a selectively stacked subset and full passive data, and validate the results against a pre-existing detailed geological information and 3D active-source survey data processed in the same way as the passive data. The resulting post-stack migrated sections show agreement of reflections between the passive and active data and indicate that VSS provide images where the active-source data are not available due to terrain restrictions. We conclude that while the all-noise approach provides some higher quality reflections related to the inner geological contacts within the target formation and the general dipping trend of the formation, the selected subset is most efficient in resolving the base of formation.

Groundwater Lowering for Construction of the Kilsby Tunnel – Geological and Geotechnical Interpretation

The Kilsby Tunnel, constructed in the 1830s, faced severe problems when a section of the tunnel, almost 400 m long, encountered unstable ‘quicksand’ conditions. The engineer for the project, Robert Stephenson, developed an extensive groundwater lowering scheme, unique for the time, using steam engines pumping from multiple shafts, to overcome the quicksand. Modern geological information indicates most of the tunnel was in Middle Lias bedrock, but the ‘quicksand’ section passed through a buried channel of water-bearing sand of glacial origin. In the early 19th century the impact of glacial processes on British geology was not widely accepted and, based on contemporary geological knowledge, Stephenson’s problems appear to be genuine unforeseen ground conditions, not predicted by his experienced advisers. It seems just random chance that trial borings missed the buried channel of sand. The work at Kilsby was two decades before Darcy’s law established the theoretical understanding for groundwater flow, and 90 years before Terzaghi’s effective stress theory described how reducing pore water pressures changed ‘quicksand’ into a stable and workable material. Despite the lack of existing theories, Stephenson used careful observations and interpretation of groundwater flow in the ‘quicksand’ to navigate the tunnel project to a successful conclusion.

GEOSPATIAL APPROACH FOR GEOLOGICAL INVESTIGATION AT DISTRICT OF MERSING

Effective geological information evaluation is essential for accurate site characterization. A major concern in geological mapping is to locate the accurate location of the geological information. The geoinformation approach such as precise GPS surveying and UAV mapping could be integrated with other geospatial information to augment the geological information. This research aims to integrate the geoinformation approach into geological structure mapping. To achieve the overall purpose of the study, the objective identified was the establishment of a high-precision control point by using Precise GPS measurement in the study area. Therefore, the establishment of GPS data observations involves the establishment of primary networks and several GPS controls points within the study area. Subsequently, the GPS positioning has been processed to produce a topographic information map and to support the collection of geological data in the study area. It is hoped that the integration of the geoinformation approach has been provided a significant increase in geological information at the district of Mersing.

Komentarz do art. 26–27 ustawy z dnia 9 czerwca 2011 r. – Prawo geologiczne i górnicze (Dz.U. 2021, poz. 1420 ze zm.)

Article 26 sets out detailed requirements of the license applications for mining of minerals from deposits. These include, in particular, information about the mineral deposit, way and size of the mining, t he r ights to use the land a nd the right to the geological information. A n appendix to such application is the “deposit development plan”, determining the way of rational use of the deposit and environmental protection. Similar requirements apply to applications for the underground non-reservoir storage of substances and underground waste depositing (Art. 27).

Investment Planning in Oil Production Enhancement Projects in Ukraine Based on Joint Usage of 3D Modelling and SPE-PRMS Reserves Classification

Most of the discovered oil fields in Ukraine entering a declining production stage. Many of these assets have good potential for production increasing and require investments. The risks of such investments are related to the uncertainty of geological information, production data, and the total amount of reserves and resources. This paper describes the study of the joint use of 3D hydrodynamic modeling and reserves estimation according to the SPE-PRMS classification, which together allowed to assess and significantly reduce investment risks for oil production enhancement projects. The use of 3D modeling is one of the key elements during field exploration and production, because of coordination of all available geological and field data it is often possible to discover new, previously unknown features of the geological structure and identify high potential areas to increase production. In this paper petrophysical, geological and hydrodynamic modeling tools and material balance method have been used to consolidate existing geological and field data and create 3D model of the field in Western oil and gas bearing region of Ukraine. Also, for uncertainty analysis of the initial hydrocarbons in-place and IOR project investment presentation the SPE-PRMS classification was used. Comprehensive usage of material balance tools, field development history analysis, well performance changes, and fluid properties behavior revealed inconsistencies in the geological data and hypothesized the existence of a gas cap in the oil deposit and identify a faults system through the reservoir. After well logging these hypotheses has been confirmed, which allowed achieving a good history match of the model for the entire field and each well. Based on the matched model, a comprehensive field development strategy was proposed, which also considered all existing limitations related to production and infrastructure issues. The best scenario of field development was selected, according to the results of the economic assessment in terms of investment attractiveness. Based on the created 3D geological model, hydrocarbons reserves and resources were estimated using deterministic and stochastic methods and have been classified according to the SPE-PRMS. Reserves categories were assessed by the degree of commercial maturity of the project based on ten possible field development scenarios and high potential zones for infill drilling, plays exploration, and IOR project implementation was selected. The integrated approach to the field development strategy assessment and the input data uncertainties allowed to consider all available geological information and field data to create a comprehensive pilot investment IOR project. The proposed approach allows to solve complex problems of potential investments risks assessment and reduction in IOR projects and discover new assets' potential on the example of a complex field in the inner zone of the Pre-Carpathian Depression.