Study of the 2012-2020 pit crater evolution in the summit caldera of Nyamulagira volcano using multiple satellite sensors and UAS-based photogrammetry

2020 ◽  
Author(s):  
Benoît Smets ◽  
Josué Subira ◽  
Antoine Dille ◽  
Nicolas Theys ◽  
Fran Broekmans ◽  
...  
Keyword(s):  
Lava Lake ◽  
Flank Eruption ◽  
Hotspot Detection ◽  
Eruptive Activity ◽  
Discharge Rates ◽  
Summit Caldera ◽  
Detailed Interpretation ◽  
Remote Sensing Techniques ◽  
Aerial Systems ◽  
Pit Crater

<p>Since its last flank eruption in 2011-2012, the activity of Nyamulagira volcano (Virunga Volcanic Province, DR Congo) has been characterized by pit crater collapse, lava fountaining and intermittent lava lake activity. No more flank eruption occurred since this concentration of the eruptive activity at the summit. As Nyamulagira is located in a remote area of the Virunga National Park, field observations remain limited. As a consequence, observations of the ongoing changes at the summit of the volcano mostly rely on satellite observations. Time-series of very-high to high resolution optical and SAR amplitude images for instance provide the required information to follow the evolution of the pit crater, from the first signs of collapse to its filling by lava. Hotspot detection from the combination of MODIS and Landsat-type images (including Sentinel-2) allows detecting the first appearance of lava in the pit crater and describing the intermittence of the lava lake activity that has developed since 2014. The OMI and TROPOMI instruments allow measuring the evolution of SO<sub>2</sub> emissions. Thanks to few aerial surveys and the use of Unoccupied Aerial Systems (UAS or “drone”), the volume of lava accumulated within the pit crater since 2014 was measured. All these satellite and drone-based observations were finally compared with the known historical eruptive activity, in terms of lava and gas discharge rates and type of summit eruptive activity. The presented work shows how combining various remote sensing techniques that make use of recent generations of satellite images and UAS acquisitions allow a detailed interpretation of the evolution of the volcano, even when field access is an issue.</p><div> </div>

Making the invisible visible: using UAS-based high-resolution color-infrared imagery to identify buried medieval monastery walls

2015 ◽  
Vol 3 (2) ◽  
pp. 58-67 ◽  
Author(s):  
Jan Rudolf Karl Lehmann ◽  
Keturah Zoe Smithson ◽  
Torsten Prinz
Keyword(s):  
Remote Sensing ◽  
Water Stress ◽  
High Resolution ◽  
Vegetation Index ◽  
Archaeological Site ◽  
Unmanned Aerial Systems ◽  
Surrounding Water ◽  
Normalised Difference Vegetation Index ◽  
Remote Sensing Techniques ◽  
Aerial Systems

Remote sensing techniques have become an increasingly important tool for surveying archaeological sites. However, budgeting issues in archaeological research often limit the application of satellite or airborne imagery. Unmanned aerial systems (UAS) provide a flexible, quick, and more economical alternative to commonly used remote sensing techniques. In this study, the buried features of the archaeological site of the Kleinburlo monastery, near Münster, Germany, were identified using high-resolution color–infrared (CIR) images collected from a UAS platform. Based on these CIR images, a modified normalised difference vegetation index (NDVIblue) was calculated, showing reflectance spectra of vegetation anomalies caused by water stress. In the presented study, the vegetation growing on top of the buried walls was better nourished than the surrounding plants because very wet conditions over the days previous to data collection caused higher levels of water stress in the surrounding water-drenched land. This difference in water stress was a good indicator for detecting archaeological remains.

scholarly journals From small-scale forest structure to Amazon-wide carbon estimates

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Edna Rödig ◽  
Nikolai Knapp ◽  
Rico Fischer ◽  
Friedrich J. Bohn ◽  
Ralph Dubayah ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Forest Biomass ◽  
3D Structure ◽  
Basal Area ◽  
Remote Sensing Data ◽  
Small Scale ◽  
Frequency Distributions ◽  
Forest Attributes ◽  
Detailed Interpretation ◽  
Remote Sensing Techniques

Abstract Tropical forests play an important role in the global carbon cycle. High-resolution remote sensing techniques, e.g., spaceborne lidar, can measure complex tropical forest structures, but it remains a challenge how to interpret such information for the assessment of forest biomass and productivity. Here, we develop an approach to estimate basal area, aboveground biomass and productivity within Amazonia by matching 770,000 GLAS lidar (ICESat) profiles with forest simulations considering spatial heterogeneous environmental and ecological conditions. This allows for deriving frequency distributions of key forest attributes for the entire Amazon. This detailed interpretation of remote sensing data improves estimates of forest attributes by 20–43% as compared to (conventional) estimates using mean canopy height. The inclusion of forest modeling has a high potential to close a missing link between remote sensing measurements and the 3D structure of forests, and may thereby improve continent-wide estimates of biomass and productivity.

scholarly journals The VEI 2 Christmas 2018 Etna Eruption: A Small But Intense Eruptive Event or the Starting Phase of a Larger One?

2020 ◽  
Vol 12 (6) ◽  
pp. 905 ◽  
Author(s):  
Sonia Calvari ◽  
Giuseppe Bilotta ◽  
Alessandro Bonaccorso ◽  
Tommaso Caltabiano ◽  
Annalisa Cappello ◽  
...  
Keyword(s):  
Ground Deformation ◽  
Volcanic Hazards ◽  
Flank Eruption ◽  
Eruptive Fissure ◽  
So2 Flux ◽  
Sequence Of Events ◽  
Shallow Earthquakes ◽  
Lava Fountains ◽  
Remote Sensing Techniques ◽  
Opening Stage

The Etna flank eruption that started on 24 December 2018 lasted a few days and involved the opening of an eruptive fissure, accompanied by a seismic swarm and shallow earthquakes, significant SO2 flux release, and by large and widespread ground deformation, especially on the eastern flank of the volcano. Lava fountains and ash plumes from the uppermost eruptive fissure accompanied the opening stage, causing disruption to Catania International Airport, and were followed by a quiet lava effusion within the barren Valle del Bove depression until 27 December. This was the first flank eruption to occur at Etna in the last decade, during which eruptive activity was confined to the summit craters and resulted in lava fountains and lava flow output from the crater rims. In this paper, we used ground and satellite remote sensing techniques to describe the sequence of events, quantify the erupted volumes of lava, gas, and tephra, and assess volcanic hazards.

scholarly journals MONITORING TERRAIN DEFORMATIONS CAUSED BY UNDERGROUND MINING USING UAV DATA

2021 ◽  
Vol XLIII-B2-2021 ◽  
pp. 737-744
Author(s):  
G. Jóźków ◽  
A. Walicka ◽  
A. Borkowski
Keyword(s):  
Underground Mining ◽  
Noisy Data ◽  
Deformation Monitoring ◽  
Unmanned Aerial Systems ◽  
Lidar Data ◽  
Digital Terrain ◽  
Terrain Models ◽  
Vertical Part ◽  
Remote Sensing Techniques ◽  
Aerial Systems

Abstract. Underground mining causes terrain surface deformations that lead to various threats to the environment and people, thus a systematic deformation monitoring needs to be performed. This monitoring mainly focuses only on the vertical part of the deformation and remote sensing techniques are currently very often used for this purpose. The development of Unmanned Aerial Systems (UASs) open new possibilities in this context. Most commonly, the mapping UASs are equipped with RGB cameras but also other lightweight sensors are utilized. In this work, the usefulness of UAS photogrammetry and LiDAR data is investigated in the context of detection and measurement of terrain deformations caused by underground mining. The accuracy of the methods was compared in reference to TLS data. The UAS and TLS measurements were performed in 2018 and 2019 but the subsidence was also evaluated in regards to ALS data acquired in 2011. The standard methodology based on Digital Terrain Models of Difference (DoDs) was applied to detect the subsidence. The DoD analysis was restricted to the hard surfaces. The profiles along the roads were also analysed to validate the accuracy of the data. The analysis showed that the UAS photogrammetry enables to obtain less noisy data and more accurate results of the terrain subsidence measurement than the UAS LiDAR sensors. The comparison of the DoDs showed about 33 cm subsidence between 2011 and 2018, which gives a subsidence rate of about 5 cm/year. The observed subsidence between years 2018 and 2019 was equal to about 5 to 15 cm depending on the measurement technique and investigated area.

The Winona Basin: structure and tectonics

1982 ◽  
Vol 19 (4) ◽  
pp. 767-788 ◽  
Author(s):  
E. E. Davis ◽  
R. P. Riddihough
Keyword(s):  
Continental Margin ◽  
Early Pleistocene ◽  
Plate Motions ◽  
Tectonic History ◽  
Discharge Rates ◽  
The Pacific ◽  
History Of ◽  
Turbidite Sedimentation ◽  
Detailed Interpretation ◽  
Sediment Layers

A compilation of published and new geophysical data from the Winona Basin off northern Vancouver Island has allowed a detailed interpretation of the sedimentary and tectonic history of the region to be made. The basin is forming as a result of the asymmetric subsidence of a recently isolated lithospheric block that is slowly converging with the continental margin. The crust beneath the basin is young (1–5 Ma, increasing in age from southeast to northwest) and of normal oceanic thickness. It is virtually non-magnetic, however, probably because of its having been rapidly buried by turbidite sedimentation. Subsidence of the basin and uplift of the Paul Revere Ridge began in the Early Pleistocene (ca. 1.8 Ma) and, since that time, up to 8 km of turbidite sediments has accumulated in the basin. The nature of the fanning of the deposits suggests that the basin has been kept full throughout its history; the minimum average supply rate necessary to accomplish this is about 70 × 106 Mg year−1. This Pleistocene average is considerably greater than the present discharge rates of any of the major rivers in the area. Subsidence, indicated by the large gravity anomaly over the basin (−130 × 10−5 m s−2 (−130 mGal)) and by the tilting of sediment layers at depth, and convergence, indicated by folding of sediments throughout the basin fill, appear to be continuing at the present time. From the timing of various events associated with the formation of the basin, we conclude that the recent reorganization of spreading and the recent relocation of the Pacific–Explorer–America triple junction have occurred in response to the demands of local small plate motions that are controlled by the interaction of the small plates with the continental margin.

The VEI 2 Christmas 2018 Etna Eruption: A small but intense eruptive event or the starting phase of a larger one?

2020 ◽  
Author(s):  
Sonia Calvari ◽  
Giuseppe Bilotta ◽  
Alessandro Bonaccorso ◽  
Tommaso Caltabiano ◽  
Annalisa Cappello ◽  
...  
Keyword(s):  
Satellite Remote Sensing ◽  
Volcanic Hazard ◽  
Ground Deformation ◽  
Flank Eruption ◽  
Eruptive Fissure ◽  
Sequence Of Events ◽  
Shallow Earthquakes ◽  
Lava Fountains ◽  
Remote Sensing Techniques ◽  
Opening Stage

<p>The Etna flank eruption started on 24 December 2018 lasted a few days and involved the opening of an eruptive fissure, accompanied by a seismic swarm and shallow earthquakes, and by large and widespread ground deformation especially on the eastern flank of the volcano. Lava fountains and ash plume from the uppermost eruptive fissure have accompanied the opening stage causing disruption of Catania international airport, and have been followed by a quiet lava effusion within the barren Valle del Bove depression until 27 December. This is the first flank eruption occurring at Etna in the last decade, during which eruptive activity was confined to the summit craters and resulted in lava fountains and lava flow output from the crater rims. In this paper we use ground and satellite remote sensing techniques to describe the sequence of events, quantify the erupted volumes of lava, gas and tephra, and assess volcanic hazard.</p>

scholarly journals Measuring River Surface Velocity with Doppler Radar and Particle Image Velocimetry (PIV) Using Unmanned Aerial Systems (UASs)

2021 ◽  
Author(s):  
Filippo Bandini ◽  
Monica Coppo Frias ◽  
Jun Liu ◽  
Kasparas Simkus ◽  
Sofia Karagkiolidou ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Doppler Radar ◽  
Low Cost ◽  
High Water ◽  
Surface Velocity ◽  
Unmanned Aerial Systems ◽  
Image Velocimetry ◽  
Remote Sensing Techniques ◽  
Aerial Systems

Surface velocity is traditionally measured with invasive techniques such as velocity probes (in shallow rivers) or Acoustic Doppler Current Profilers (in deeper water). In the last years, researchers have developed remote sensing techniques, both optical (e.g. image-based velocimetry techniques) and microwave (e.g. Doppler radar). These techniques can be deployed from Unmanned Aerial Systems (UAS), which ensure fast and low-cost surveys also in remote locations. We compare the results obtained with a UAS-borne Doppler radar and UAS-borne Particle Image Velocimetry (PIV) in different rivers, which presented different hydraulic conditions (width, slope, surface roughness and sediment material). The Doppler radar was a commercial 24 GHz instrument, developed for static deployment, adapted for UAS integration. PIV was applied with natural seeding (e.g. foam, debris) when possible or, with artificial seeding (woodchips) in the stream where the density of natural particles was insufficient. PIV reconstructed the velocity profile with high accuracy typically in the order of a few cm/s in all investigated rivers, whilst UAS-borne radar was only successful in locations with high water roughness. However, UAS integration of Doppler radar is complex because of vibrations, large instrument sampling footprint, large required sampling time and difficult-to-interpret quality indicators.

scholarly journals Ina pit crater on the Moon: Extrusion of waning-stage lava lake magmatic foam results in extremely young crater retention ages

Geology ◽  
2017 ◽  
Vol 45 (5) ◽  
pp. 455-458 ◽  
Author(s):  
Le Qiao ◽  
James Head ◽  
Lionel Wilson ◽  
Long Xiao ◽  
Mikhail Kreslavsky ◽  
...  
Keyword(s):  
Lava Lake ◽  
The Moon ◽  
Pit Crater
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