2000 Uglegorsk earthquake

The paper presents the results of waveform inversion of the Mw 6.8 August 4 (5), 2000 Uglegorsk earthquake (Sakhalin Island, Russia). The detailed rupture process of the 2000 Uglegorsk earthquake was simulated using the waveform inversion method. The average parameters were calculated for both nodal planes. Waveform inversion was carried out on the basis of Global Seismographic Network (GSN) data. Only P-waves from BHZ channels of all stations from the GSN were used. The simulated source parameters included a double-couple source, the scalar seismic moment, the source time function, and the slip directions. The performed studies made it possible to investigate the features of the rupture development and the amplitude of displacements along the east and west-dipping nodal planes of the August 4 (5), 2000 Uglegorsk earthquake. The obtained P-slip model for the 2000 Uglegorsk earthquake source area is in good agreement with the surface manifestations of the rupture according to the field geology data and the results of geodetic inversion.

Subduction and exhumation slip accommodation at depths of 10–80 km inferred from field geology of exhumed rocks: Evidence for temporal-spatial localization of slip

ABSTRACT Field relationships in the Franciscan Complex of California suggest localization of subduction slip in narrow zones (≤300 m thick) at the depths of ∼10–80 km. Accretionary and non-accretionary subduction slip over the ca. 150 Ma of Franciscan history was accommodated across the structural thickness of the complex (maximum of ∼30 km). During accretion of a specific unit (<5 Ma), subduction slip (accretionary subduction slip) deformed the full thickness of the accreting unit (≤5 km), primarily on discrete faults of <20 m in thickness, with the remainder accommodated by penetrative deformation. Some faults accommodating accretionary subduction slip formed anastomosing zones ≤200 m thick that resulted in block-in-matrix (tectonic mélange) relationships but did not emplace exotic blocks. Mélange horizons with exotic blocks range in thickness from 0.5 m to 1 km. These apparently formed by sedimentary processes as part of the trench fill prior to subsequent deformation during subduction-accretion. Accretionary subduction slip was localized within some of these mélanges in zones ≤300 m thick. Such deformation obscured primary sedimentary textures. Non-accretionary subduction faults separate units accreted at different times, but these <100-m-thick fault zones capture a small fraction of associated subduction slip because of footwall subduction and likely removal of hanging wall by subduction erosion. Most exhumation was accommodated by discrete faults ≤30 m thick. Structural, geochronologic, and plate motion data suggest that of the ∼13,000 km of subduction during the ca. 150 Ma assembly of the Franciscan Complex, ∼2000 km was associated with accretion.

Achieving mutual accessibility through the coordination of multiple perspectives in open, unstructured landscapes

Whenever actors perceptually engage with the surrounding world in concert with others, they routinely attend to the degree to which their perceptions (whether visual, aural, tactile, etc.) do or do not overlap with their co-participants. In making a perception publicly accessible then, participants must not only attend to potential perceptual gaps, but have-at-hand a range of discursive and embodied practices for closing those and making what is perceived by one mutually accessible to others. In this paper, using data collected from a geological field-school, I investigate the embodied and mobile practices that participants use for coordinating perception via perspective in open, wilderness settings. I focus in particular on the visual practices that participants use for making what one “sees” in the landscape or activity “seeable" for others. These practices are in turn analyzed with regard to how they highlight the camera’s role in documenting the embodied means by which these practices work. In the analysis of data, we will see the participants’ perspective or line of sight, i.e., the axis of their gaze become a more explicit and salient feature for coordinating the interaction. Field geology provides a perspicuous setting for not just investigating how participants reconfigure themselves vis-a-vis local features in the landscape in order to perceive those features, but also for examining the relationship between the videographer’s perspective as documented on camera and that of the participants.

Supplemental Material: Subduction and exhumation slip accommodation at depths of 10–80 km inferred from field geology of exhumed rocks: Evidence for temporal-spatial localization of slip

Figures 7, 8, 10, 11, 12, and 13 for zoom-in viewing.

Supplemental Material: Subduction and exhumation slip accommodation at depths of 10–80 km inferred from field geology of exhumed rocks: Evidence for temporal-spatial localization of slip

Figures 7, 8, 10, 11, 12, and 13 for zoom-in viewing.

МEMORIES ON THE FIELD COURSE IN GEOLOGICAL MAPPING

This article is a memory of the field course in geological mapping. It was a part of studying process of the author while her education at the Geology & Geophysics Department, Novosibirsk University. The practice took place in the 80s of the last century in the steppe region of the Khakassia Autonomous Region (Krasnoyarsk Territory, Russia) at the university’s geological training camp. The article features a technique of creating a geological map of the site. Geological strata were distinguished by lithological features. However, the instructors did not indicate the real geological age of the deposits to the students because it was believed that such information is unnecessary for them. The main task of students was to master the methods of geological mapping of an unknown territory. Students covered the site with routes along the cross of the strike of sediments. Students had to recognize these sediments, determine the area of their distribution, divide them into stratigraphic horizons and give them their own names. Then students marked the boundaries of the rock layers at outcrops and the elements of their occurrence on the topographic base. This original teaching method gave a positive result. Students have developed a geological map of the training site where certain stratigraphic horizons were shown with real bedding elements. This approach contributed to the independent creative work of students. Students felt themselves like pioneer geologists who came to this territory for the first time, conducted geological mapping and gave names to geological strata that are exposed. In addition, this method excluded the possibility of cheating and copying the existing real geological map. The article presents memories of the young nineteen-year-old student’s perception of the features of field geology, expeditionary life and collective work. With a certain degree of self-irony the author brings his thoughts, feelings and impressions of nature. The experience gained during this field practice has become the basis of the author’s professional skills and now helps us in educational process.

Digital Geological Mapping to Facilitate Field Data Collection, Integration, and Map Production in Zhoukoudian, China

The development of innovative information technologies has improved the geological mapping process through the use of smart and portable equipment to collect field data, build a geological database and produce geological maps. This revolution has also brought great influence and challenges to practical training in field geology. In this paper, we present our workflow and application of the Digital Geological Survey System (DGSS) during field geology training for undergraduates in Zhoukoudian. The DGSS employs a Point-Routing-Boundary (PRB) model to reform the methods of geological section survey and geological mapping in terms of data collection and map-making and provides a pipelined solution from field data collection to map-making. The experiences of data collection, geological mapping, cross-section survey, and production of stratigraphic histograms and cross-section maps prove that DGSS can save time and reduce labor intensity for undergraduates during learning field geology. Based on the field practice of undergraduates in Zhoukoudian, the influence of the DGSS in promoting field geological teaching and the students’ feedbacks to DGSS are discussed. Overall, the DGM system is more popular than the conventional notebook and toolbox. The experience in Zhoukoudian proves that digital devices are efficient and useful for geological practical training of field geology for undergraduates.