Catálogo de publicaciones - revistas

<jats:p> Commercial sensors for seismic data collection have changed little in the previous 20 years. The sensors that are available today have exceptional dynamic range and sensitivity. This paper explores and compares the field response of analog geophones and all-digital microelectrical-mechanical-sensors-based accelerometers from the perspective of the dynamic range of the recorded data. Also discussed are other characteristics of each sensor type and the potential impact on seismic data quality. </jats:p>

<jats:p> A stepped-frequency continuous-wave radar system has been designed and integrated into a drill head for use on midrange horizontal directional drills. Data from the forward-looking radar are acquired, processed, and displayed in near real time. A unique, computationally efficient target detection algorithm has been developed and tested to predict the position of potential obstacles in front of the drill head. This method is called derivative imaging, and it provides distance to target and radial offset information such that the drill operator may respond accordingly. Application to traditional ground-penetrating radar systems is also demonstrated. </jats:p>

<jats:p> As carbon capture, utilization, and sequestration scales toward the gigatonnes level, the need for underground reservoir surveillance is driving efforts in advancing technologies for cost-effective passive seismic monitoring. Quantum Technology Sciences, in cooperation with Carbon Management Canada's Containment and Monitoring Institute (CaMI), installed a network of four permanent compact volumetric phased arrays (seismic and acoustic detection and ranging [SADAR] system) at CaMI's Field Research Station (FRS) to demonstrate the results that can be achieved through passive monitoring of microseismicity using this technology. Configured as a sparse network, the SADAR arrays provide passive, persistent, and permanent data acquisition and analysis for monitoring microseismicity in the earth volume of interest. Data from the phased arrays are processed to take advantage of the spatial coherence of the incident seismic signals to increase signal resolution while suppressing noise and clutter signals and providing signal attributes such as angle of incidence and phase velocity. The CaMI FRS has a network of 28 permanent surface stations that are deployed in an x-shaped geometry centered on the injection well. It has a downhole array of 24 geophones that are permanently deployed in an observation well. This provides a ready and unique opportunity to evaluate the detection and location performance of the different systems for passive seismic monitoring. We analyze observations of five example events selected from the microseismicity detected by the SADAR arrays with moment magnitudes (M<jats:sub>w</jats:sub>) down to approximately −2. Signal-to-noise ratio (S/N) and location uncertainties are compared for the events acquired using SADAR arrays versus the surface sensors. The results demonstrate improved performance of networked SADAR arrays compared to traditional surface sensor deployment for detecting and locating microseismicity. Specifically, the results show that coherent processing of SADAR arrays achieves S/N gains up to about 20 dB and location errors down to 10 m. </jats:p>

<jats:p> Submarine landslides are a mixture of rock, sediment, and fluids moving downslope due to a slope's initial event of mechanical failure. Submarine landslides play a critical role in shaping the morphology of the seafloor and the transport of sediments from the continental shelf to the continental rise in the southern margin of the Colombian Caribbean. Two fundamental considerations can be highlighted: first, mass transport complexes produced by submarine landslides encompass significant portions of the stratigraphic record; second, these mass movements could affect underwater infrastructure. The mapping of the Southern Caribbean seafloor using 3D seismic surveys and multibeam bathymetry data in an area encompassing 59,471 km<jats:sup>2</jats:sup> allowed the identification of 220 submarine landslides with areas ranging between 0.1 and 209 km<jats:sup>2</jats:sup>. Distinctive characteristics were found for submarine landslides associated with canyon walls, channel-levee systems, tectonically controlled ridges, and the continental shelf break. The analysis of the relationship between submarine landslides and seafloor morphological features made it possible to estimate a mass movement susceptibility map that suggests the following considerations: first, structural ridges and adjacent intraslope subbasins related to the South Caribbean Deformed Belt are more likely to be submarine landslide hazards; second, the continental shelf break and channelized systems produce a moderate submarine landslide hazard potential; and third, deep marine systems with a slope less than 5° show the lowest submarine landslide hazard potential. This work contributes to the understanding of submarine landslides in the study area through the presentation of conceptual diagrams that provide additional visual elements facilitating the level of abstraction necessary for visualizing bathymetric data. Likewise, the mass movement susceptibility map presented herein gives insights for future studies that seek to evaluate geohazards in the southern Colombian Caribbean margin. </jats:p>

<jats:p> Over the past decade, computing power has increased, new sensing technologies have been developed, and our understanding of how we interact with the earth has evolved, leading to new opportunities and priorities in geophysical research. These changes have been more rapid in some areas than others, and new topics have emerged as well. It is challenging for geophysicists, including junior staff and undergraduates starting their geophysics journeys, to stay abreast of scientific and industrial trends. Thus, the Early Career Subcommittee of the SEG Research Committee (RC) thought it imperative to survey members of the RC in 2022. To that end, a survey was conducted, and responses were collected from 43 RC members. </jats:p>

<jats:p> Welcome to the latest installment of Geophysics Bright Spots. There are a number of interesting research articles in the recent issue of Geophysics. Here is an article that piqued the editors’ interests. </jats:p>

<jats:p> Modern Computer Vision with PyTorch: Explore Deep Learning Concepts and Implement Over 50 Real-World Image Applications, by V. Kishore Ayyadevara and Yeshwanth Reddy, 2020. </jats:p>

<jats:p> Nominees for 2023–2024 SEG Board of Directors </jats:p>

<jats:p> Norman Reed Paterson </jats:p>

<jats:p> Applications for Active membership have been received from the candidates listed herein. </jats:p>