Framing bias : the effect of figure presentation on seismic interpretation

The authors thank all the participants in the survey, and those who helped to distribute it. We thank Prof. Christopher Jackson and co-authors for allowing the use of their published images in this experiment. Juan Alcalde is funded by NERC grant NE/M007251/1, on interpretational uncertainty.Peer reviewedPublisher PD

The 3D Attenuation Structure of Deception Island (Antarctica)

Peer reviewedPostprin

Report of the panel on lithospheric structure and evolution, section 3

The panel concluded that NASA can contribute to developing a refined understanding of the compositional, structural, and thermal differences between continental and oceanic lithosphere through a vigorous program in solid Earth science with the following objectives: determine the most fundamental geophysical property of the planet; determine the global gravity field to an accuracy of a few milliGals at wavelengths of 100 km or less; determine the global lithospheric magnetic field to a few nanoTeslas at a wavelength of 100 km; determine how the lithosphere has evolved to its present state via acquiring geologic remote sensing data over all the continents

Landscapes of human evolution : models and methods of tectonic geomorphology and the reconstruction of hominin landscapes

This paper examines the relationship between complex and tectonically active landscapes and patterns of human evolution. We show how active tectonics can produce dynamic landscapes with geomorphological and topographic features that may be critical to long-term patterns of hominin land use but that are not typically addressed in landscape reconstructions based on existing geological and paleoenvironmental principles. We describe methods of representing topography at a range of scales using measures of roughness based on digital elevation data, and combine the resulting maps with satellite imagery and ground observations to reconstruct features of the wider landscape as they existed at the time of hominin occupation and activity. We apply these methods to sites in South Africa, where relatively stable topography facilitates reconstruction, and demonstrate the presence of previously unrecognized tectonic effects and their implications for the interpretation of hominin habitats and land use. In parts of the East African Rift, reconstruction is more difficult because of dramatic changes since the time of hominin occupation, while fossils are often found in places where activity has now almost ceased. However, we show that original, dynamic landscape features can be assessed by analogy with parts of the Rift that are currently active and indicate how this approach can complement other sources of information to add new insights and pose new questions for future investigation of hominin land use and habitats

Knowledge-based systems and geological survey

This personal and pragmatic review of the philosophy underpinning methods of geological surveying suggests that important influences of information technology have yet to make their impact. Early approaches took existing systems as metaphors, retaining the separation of maps, map explanations and information archives, organised around map sheets of fixed boundaries, scale and content. But system design should look ahead: a computer-based knowledge system for the same purpose can be built around hierarchies of spatial objects and their relationships, with maps as one means of visualisation, and information types linked as hypermedia and integrated in mark-up languages. The system framework and ontology, derived from the general geoscience model, could support consistent representation of the underlying concepts and maintain reference information on object classes and their behaviour. Models of processes and historical configurations could clarify the reasoning at any level of object detail and introduce new concepts such as complex systems. The up-to-date interpretation might centre on spatial models, constructed with explicit geological reasoning and evaluation of uncertainties. Assuming (at a future time) full computer support, the field survey results could be collected in real time as a multimedia stream, hyperlinked to and interacting with the other parts of the system as appropriate. Throughout, the knowledge is seen as human knowledge, with interactive computer support for recording and storing the information and processing it by such means as interpolating, correlating, browsing, selecting, retrieving, manipulating, calculating, analysing, generalising, filtering, visualising and delivering the results. Responsibilities may have to be reconsidered for various aspects of the system, such as: field surveying; spatial models and interpretation; geological processes, past configurations and reasoning; standard setting, system framework and ontology maintenance; training; storage, preservation, and dissemination of digital records

Unrest at Domuyo Volcano, Argentina, detected by geophysical and geodetic data and morphometric analysis

New volcanic unrest has been detected in the Domuyo Volcanic Center (DVC), to the east of the Andes Southern Volcanic Zone in Argentina. To better understand this activity, we investigated new seismic monitoring data, gravimetric and magnetic campaign data, and interferometric synthetic aperture radar (InSAR) deformation maps, and we derived an image of the magma plumbing system and the likely source of the unrest episode. Seismic events recorded during 2017-2018 nucleate beneath the southwestern flank of the DVC. Ground deformation maps derived from InSAR processing of Sentinel-1 data exhibit an inflation area exceeding 300 km2, from 2014 to at least March 2018, which can be explained by an inflating sill model located 7 km deep. The Bouguer anomaly reveals a negative density contrast of ~35 km wavelength, which is spatially coincident with the InSAR pattern. Our 3D density modeling suggests a body approximately 4-6 km deep with a density contrast of -550 kg/m3. Therefore, the geophysical and geodetic data allow identification of the plumbing system that is subject to inflation at these shallow crustal depths. We compared the presence and dimensions of the inferred doming area to the drainage patterns of the area, which support long-established incremental uplift according to morphometric analysis. Future studies will allow us to investigate further whether the new unrest is hydrothermal or magmatic in origin.Fil: Astort, Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Walter, Thomas R. German Research Centre for Geosciences; AlemaniaFil: Ruiz, Francisco. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; ArgentinaFil: Sagripanti, Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Nacif, Andres Antonio. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; ArgentinaFil: Acosta, Gemma. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Folguera Telichevsky, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentin

Methods to analyse and interpret shallow seismic data: onshore central Perth basin, Western Australia

The main aim of the research was to develop a methodology for inferring complex sub-surface shallow structures from seismic data that are of a high relevance to hydrological studies in Perth Basin. A set of realistic 2D and 3D numerical modelling experiments were conducted that show that in the best case it is possible to interpret complex geological structure from 3D seismic data

Identification of the physical controls on the deposition of Aptian and Albian deep water sands in the Bredasdorp Basin, South Africa

In the petroleum industry, the location of a new well is selected based on several factors, one of which is the presence of reservoir-quality sands. To determine the lateral extent of these sands away from well control, the depositional environment and character of the deposit must be adequately identified. This study aims to explain the physical controls on the deposition of the 13A (Aptian) and 14A (Albian) sequence sands within the deep water region of the Central Bredasdorp Basin through identifying the mass transport facies and processes and relating these to tectono-eustatic factors. Since a primarily seismic-based approach was used to achieve the project objective, the results reflect findings based on 3D seismic data interpretations as well as seismic surface and volume attribute extraction supported by wireline well logs and well completion reports. This dataset contains information that enabled the identification of the structural and stratigraphic architecture of the 13A and 14A sequences as a whole, the location of the sediment provenances and possible triggers of the mass flows as well as the consequential sand distribution trends from the basin slopes to across the basin floor during the Aptian-Albian time. The onshore Tankwa Basin was studied as an analogue to the Bredasdorp Basin because it hosts world class outcrops of deep water lowstand fan deposits and therefore shows the finer-scale details of the associated depositional stratigraphy. The 13A and 14A sequence sands would have entered the Bredasdorp Basin in progradational pulses alternating with mud-rich successions associated with local sea level fluctuations that were on trend with the gradual global sea level rise from the Aptian to the Albian. These alternating successions are identified as lowstand, transgressive and highstand systems tracts in the seismic and wireline well log data used in this study. The presented depositional model of the 13A sequence sands is a system of northwest to southeast sediment transport across the Central Bredasdorp Basin with indications of a final swing in orientation towards the east. The sands were mainly sourced from the paleo shelf edge on the northwest margin, although additional sediment input may have come from the west too. The faults that were active before and during the deposition of the Aptian-aged (13A) sands appear to have been the main control on sand distribution across the basin, guiding the sands from slope channels into basin floor fans and from shelf edge slumps into base of slope fans in a basinwide northwestsoutheast trend. The model of deposition of the 14A sequence sands is based on a channelised flow of sediment from the Central Bredasdorp Basin paleo shelf edge, down the slope and onto the basin floor primarily from the onshore source on the western margin. Supplementary sediment input may have originated from the Agulhas basement high on the southern margin of the basin in the form of less confined channels and mass wasting deposits. Inherited topography of the sea floor at the Albian time appears to have been the primary control on 14A sand distribution, causing bypass zones and giving rise to narrow, confined channel complexes despite some of the active faults possibly redirecting some of the sands from their initial trend. Overall the pattern of deposition of the Aptian and Albian deep water sands in the Bredasdorp Basin appears to have been physically controlled by the regional paleo seabed topography and fault activity until the late Aptian