Integration between data collection through field and UAV-based surveys in volcano-tectonic environments: an example from the Krafla Fissure Swarm (NE Iceland)

2021 ◽  
Author(s):  
Sofia Bressan ◽  
Noemi Corti ◽  
Valentina Rigoni ◽  
Elena Russo
Keyword(s):  
Late Glacial ◽  
3D Models ◽  
Normal Faults ◽  
Central Volcano ◽  
Volcanic System ◽  
Field Surveys ◽  
Geological Processes ◽  
Fissure Swarm ◽  
Surface Models ◽  
Eruptive Fissures

<p>Due to its strategic position at the boundary between European and American plates, Iceland is extraordinarily well suited for the investigation of various geological processes, like the interaction between active rifting processes and magmatic stresses. In this study, we focused on surveying with very high detail different key areas located within the Krafla Fissure Swarm (KFS), an active volcanic system located in the Northern Volcanic Zone, NE Iceland.</p><p>The Krafla volcanic rift is characterized by the presence of a central volcano and by a 100 km-long swarm of extension fractures, normal faults and eruptive fissures mainly affecting post-LGM (Late Glacial Maximum) Holocene lavas. Our work focuses on three different areas, located in the northernmost sector of the rift, about 5 km north of the central caldera, and south of the central volcano. All these areas have been investigated through field surveys performed both with classical methods and through two Unmanned Aerial Vehicles (UAVs), the DJI Phantom 4 PRO and DJI Spark: thanks to Structure from Motion (SfM) photogrammetry techniques, we obtained Orthomosaics, Digital Surface Models (DSMs) and 3D models of the study area, with centimetric resolution.</p><p> The integration of the above cited methodologies allowed us to collect a huge amount of data, also overcoming difficulties due to logistics, which can sometimes impede classical field survey. More in detail, we collected 2476 structural measurements at 918 sites along extension fractures, and at 185 sites along normal faults. At extension fractures, we measured local fracture strike, dilation and, whenever possible, opening direction. On the other hand, along normal faults we measured local fault strike and the vertical offset. From our data, we obtained an average opening direction of N101°E, thus observing the presence of lateral components of motion along extension fractures. Finally, considering both extension fractures and normal faults, we quantified the cumulative dilation along these sectors, in order to assess the stretch value along the rift.</p>

scholarly journals Fracture Kinematics and Holocene Stress Field at the Krafla Rift, Northern Iceland

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 101
Author(s):  
Noemi Corti ◽  
Fabio L. Bonali ◽  
Federico Pasquaré Mariotto ◽  
Alessandro Tibaldi ◽  
Elena Russo ◽  
...  
Keyword(s):  
Normal Fault ◽  
Late Glacial ◽  
Stretch Ratio ◽  
Normal Faults ◽  
Central Volcano ◽  
Field Surveys ◽  
Average Value ◽  
A Value ◽  
Extensive Field ◽  
Orientation Average

In the Northern Volcanic Zone of Iceland, the geometry, kinematics and offset amount of the structures that form the active Krafla Rift were studied. This rift is composed of a central volcano and a swarm of extension fractures, normal faults and eruptive fissures, which were mapped and analysed through remote sensing and field techniques. In three areas, across the northern, central and southern part of the rift, detailed measurements were collected by extensive field surveys along the post-Late Glacial Maximum (LGM) extension fractures and normal faults, to reconstruct their strike, opening direction and dilation amount. The geometry and the distribution of all the studied structures suggest a northward propagation of the rift, and an interaction with the Húsavík–Flatey Fault. Although the opening direction at the extension fractures is mostly normal to the general N–S rift orientation (average value N99.5° E), a systematic occurrence of subordinate transcurrent components of motion is noticed. From the measured throw at each normal fault, the heave was calculated, and it was summed together with the net dilation measured at the extension fractures; this has allowed us to assess the stretch ratio of the rift, obtaining a value of 1.003 in the central sector, and 1.001 and 1.002 in the northern and southern part, respectively.

Reconstruction of the entire rift architecture of Theistareykir Fissure Swarm (northeast Iceland): integration between extensive UAV and field surveys

2021 ◽  
Author(s):  
Elena Russo ◽  
Noemi Corti ◽  
Fabio Luca Bonali ◽  
Alessandro Tibaldi ◽  
Federico Pasquaré Mariotto ◽  
...  
Keyword(s):  
Late Glacial ◽  
Normal Faults ◽  
Crustal Rock ◽  
Field Surveys ◽  
Quantitative Measurements ◽  
Fissure Swarm ◽  
Rift Propagation ◽  
Extensive Field ◽  
Structural Architecture ◽  
Rock Rheology

<p>Reconstructing the origin and kinematics of structures along active rifts is essential to gain a deeper knowledge on rifting processes, with important implications for the assessment of volcanic and seismic hazard. Here we reconstruct the architecture of an entire rift, the 70-km-long Theistareykir Fissure Swarm (ThFS) within the Northern Volcanic Zone of Iceland, through the collection of an extensive amount of 7500 quantitative measurements along extension fractures and normal faults, thanks to the integration between Unmanned Aerial Vehicles (UAV) mapping with centimetric resolution through Structure from Motion (SfM) techniques and extensive field surveys with classical methods. Quantitative measurements, collected across a wide area during several campaigns, comprise strike, opening direction and amount of opening at extension fractures, and strike and offset values at faults, along 6124 post-Late Glacial Maximum (LGM) and 685 pre-LGM structures.</p><p>The extent of the area covered by our data allowed us to pinpoint differences in the structural architecture of the rift. From south to north: i) extension fractures and faults strike ranges from mainly N10°-20°, to N00-10°, to N30-40°; ii) the opening direction starts from N110°, reaches N90-100° in the center and amounts to N125° in the northernmost sector; and iii) the dilation amount is in the range 0.1–10 m, then 0.1–9 m and it finally reaches 0.1–8 m. We explore such differences as due to the interaction with the WNW-ESE-striking Husavik-Flatey transform fault and the Grímsey Oblique Rift (Grímsey lineament), and to the structural inheritance of older NNE- to NE-striking normal faults. The reconstruction of the stress field resulting from such data allows the interpolation of the σ<sub>hmin</sub> values, through the unpublished software ATMO-STRESS, prepared in the framework of the EU NEANIAS project, in order to plot and examine the strain field.</p><p>Furthermore, mechanisms of rift propagation and the relation between magma systems are here investigated through the analysis of 281 slip profiles of the main Pleistocene-Holocene faults. Our data show a mechanism of along-axis propagation of the rift outward from the volcano: in fact, north of the volcano, 75% of the asymmetric faults propagated northward, whereas south of the volcano 47% of the asymmetric faults propagated southward. This can be due to the combination between the development of faults following lateral dyke propagation outward from the magma chamber, and faults nucleation near the volcano as a consequence of the different crustal rock rheology produced by a higher heat flux.</p>

Structural analysis of the Theistareykir Fissure Swarm (NE Iceland) using field survey integrated with UAV-based - Structure from Motion techniques

2020 ◽  
Author(s):  
Noemi Corti ◽  
Alessandro Tibaldi
Keyword(s):  
Structure From Motion ◽  
Field Survey ◽  
Late Quaternary ◽  
3D Models ◽  
Normal Faults ◽  
Large Area ◽  
Southern Sector ◽  
Fissure Swarm ◽  
Aerial Vehicle ◽  
Extension Fracture

<p>Due to its position at the boundary between American and European plates, Iceland represents an ideal natural laboratory to study active rifting processes, where rifting mechanisms are complicated by the superimposition of tectonic and magmatic stresses. In order to contribute to the study of such processes, we focused our attention on the southern sector of the Theistareykir Fissure Swarm (ThFS), an active volcanic rift belonging to the Northern Volcanic Zone of Iceland, affected by both volcanic and seismic hazard.</p><p>We studied an area which is about 22 km<sup>2</sup>-large, situated 12 km south of the intersection of the ThFS with the Husavik Flatey Fault (HFF), a dextral strike-slip lineament belonging to the Tjornes Fracture Zone (TFZ). The area is characterized by the presence of normal faults and a dense swarm of extension fractures, affecting prevalently post-glacial, Holocene lavas, dated 8-10 and 11-12 ka. Only in the western sector of the area a Late Quaternary interglacial lava crops out, while the northeastern sector is covered by a Weichselian subglacial hyaloclastite. The southern sector of the area has been investigated with classical field survey, whereas in the northern part a 3.87 km<sup>2</sup>-large area has been reconstructed using the Structure from Motion (SfM) techniques, combined with an Unmanned Aerial Vehicle (UAV), obtaining orthomosaics, DSMs and 3D models with a centimetric resolution through 4189 UAV photos, collected in 7 different missions during summer 2018.</p><p>In the whole area, we recognized and mapped a total of 624 structures (comprising 583 extension fractures and 41 normal faults), and we took various measurements at 626 structural stations along extension fractures, and 132 along normal faults. Regarding extension fractures, we collected the strike and, in 441 cases where it was possible, the opening direction and the amount of opening; along normal faults we measured the strike, dip and vertical offset.</p><p>Our approach allowed to calculate stretch values across the rift comprised between 1.002 and 1.013, and an average opening direction value of 104.4°N, normal to the average extension fracture strike measured at the structural stations (14°N), suggesting a pure extensional opening in the studied area. Actually, in 281 cases out of our 441 stations along extension fractures we noticed a lateral component > 5°. Furthermore, 49% of data is not consistent with tectonics, neither with regard to the extensional fracture strike, nor with regard to opening directions. This suggests that stresses linked to regional tectonics are not the only cause of deformation, which could have been affected by different processes like dyke intrusion, deglaciation, and inflation/deflation of the Theistareykir volcano magma chamber.</p>

UAV- and SfM-related techniques applied to volcano-tectonics for virtual outcrops construction and geoscience communication. Examples from the North Volcanic Zone, Iceland

2020 ◽  
Author(s):  
Federico Pasquaré Mariotto ◽  
Alessandro Tibaldi
Keyword(s):  
Environmental Science ◽  
Volcanic Eruptions ◽  
Environmental Research ◽  
Rift System ◽  
Central Volcano ◽  
High Definition ◽  
Volcanic Zone ◽  
The North ◽  
Fissure Swarm ◽  
Eruptive Fissures

<p><strong>UAV- and SfM-related techniques applied to volcano-tectonics for virtual outcrops construction and geoscience communication. Examples from the North Volcanic Zone, Iceland</strong></p><p><strong> </strong><strong>Authors:</strong> Federico Pasquaré Mariotto<sup>1</sup>, Alessandro Tibaldi<sup>2,3</sup></p><p><sup> </sup></p><p><sup>1</sup>Insubria University, Department of Human and Innovation Sciences                     <sup>2</sup>University of Milan-Bicocca, Department of Earth and Environmental Science, Milan, Italy <sup>3</sup>CRUST- Interuniversity Center for 3D Seismotectonics with Territorial Applications, Italy</p><p> </p><p>Iceland offers an unparalleled chance to observe the most powerful natural phenomena related to the combination of tectonic and magmatic forces, such as active rifting, volcanic eruptions, sub-volcanic intrusions. We have focused on a number of geosites which are found in the Northern Volcanic Zone (NVZ) of Iceland; here, the following volcano-tectonic features can be observed: i) the Theystareykir  Fissure Swarm (ThFS), an active rift system with a central volcano, several major faults and numerous eruptive fissures; ii) the Krafla Fissure Swarm (KFS), another major rift system marked by the presence of monogenetic cones, dip-slip faults, eruptive fissures, extension fractures and the active Krafla volcano.</p><p>In order to showcase a few, outstanding examples of the above, we have made use of UAVs integrated by the Structure-from-Motion (SfM) Photogrammetry. As is well known, the combination of UAV-digital image collection and SfM techniques has been increasingly applied to geological and environmental research. We have applied this approach to the collection of high-definition images and with the purpose of constructing 3-D models, which may be considered “Virtual Outcrops (VO)”.</p><p>We highlight that such 3-D models can be navigated in immersive Virtual Reality mode, and hence can be a key tool not only for research purposes: in fact, this is a novel, cutting-edge approach which is suitable for improving geosite popularization and geoscience communication, allowing for the engagement of a wider audience, including potential end-users from the younger generation.</p><p> </p><p><strong> </strong></p>

scholarly journals Soft Tissue Stability around Single Implants Inserted to Replace Maxillary Lateral Incisors: A 3D Evaluation

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
F. G. Mangano ◽  
F. Luongo ◽  
G. Picciocchi ◽  
C. Mortellaro ◽  
K. B. Park ◽  
...  
Keyword(s):  
Soft Tissue ◽  
South Korea ◽  
Soft Tissues ◽  
3D Models ◽  
Lateral Incisor ◽  
Engineering Software ◽  
3D Surface ◽  
Immediate Placement ◽  
Surface Models ◽  
3D Evaluation

Purpose. To evaluate the soft tissue stability around single implants inserted to replace maxillary lateral incisors, using an innovative 3D method.Methods. We have used reverse-engineering software for the superimposition of 3D surface models of the dentogingival structures, obtained from intraoral scans of the same patients taken at the delivery of the final crown (S1) and 2 years later (S2). The assessment of soft tissues changes was performed via calculation of the Euclidean surface distances between the 3D models, after the superimposition of S2 on S1; colour maps were used for quantification of changes.Results. Twenty patients (8 males, 12 females) were selected, 10 with a failing/nonrestorable lateral incisor (testgroup: immediate placement in postextraction socket) and 10 with a missing lateral incisor (controlgroup: conventional placement in healed ridge). Each patient received one immediately loaded implant (Anyridge®, Megagen, Gyeongbuk, South Korea). The superimposition of the 3D surface models taken at different times (S2 over S1) revealed a mean (±SD) reduction of 0.057 mm (±0.025) and 0.037 mm (±0.020) fortestandcontrolpatients, respectively. This difference was not statistically significant (p= 0.069).Conclusions. The superimposition of the 3D surface models revealed an excellent peri-implant soft tissue stability in both groups of patients, with minimal changes registered along time.

scholarly journals Advanced radar-interpretation of InSAR time series for mapping and characterization of geological processes

2011 ◽  
Vol 11 (3) ◽  
pp. 865-881 ◽  
Author(s):  
F. Cigna ◽  
C. Del Ventisette ◽  
V. Liguori ◽  
N. Casagli
Keyword(s):  
Time Series ◽  
Field Surveys ◽  
Synthetic Aperture Radar Interferometry ◽  
Geological Processes ◽  
Multi Temporal ◽  
Under Sampling ◽  
Temporal Measures

Abstract. We present a new post-processing methodology for the analysis of InSAR (Synthetic Aperture Radar Interferometry) multi-temporal measures, based on the temporal under-sampling of displacement time series, the identification of potential changes occurring during the monitoring period and, eventually, the classification of different deformation behaviours. The potentials of this approach for the analysis of geological processes were tested on the case study of Naro (Italy), specifically selected due to its geological setting and related ground instability of unknown causes that occurred in February 2005. The time series analysis of past (ERS1/2 descending data; 1992–2000) and current (RADARSAT-1 ascending data; 2003–2007) ground movements highlighted significant displacement rates (up to 6 mm yr−1) in 2003–2007, followed by a post-event stabilization. The deformational behaviours of instable areas involved in the 2005 event were also detected, clarifying typology and kinematics of ground instability. The urban sectors affected and unaffected by the event were finally mapped, consequently re-defining and enlarging the influenced area previously detected by field observations. Through the integration of InSAR data and conventional field surveys (i.e. geological, geomorphologic and geostructural campaigns), the causes of instability were finally attributed to tectonics.

scholarly journals Three-Dimensional Reconstruction of Structural Surface Model of Heritage Bridges Using UAV-Based Photogrammetric Point Clouds

2019 ◽  
Vol 11 (10) ◽  
pp. 1204 ◽  
Author(s):  
Yue Pan ◽  
Yiqing Dong ◽  
Dalei Wang ◽  
Airong Chen ◽  
Zhen Ye
Keyword(s):  
Classification Tree ◽  
Three Dimensional ◽  
Point Clouds ◽  
3D Models ◽  
Surface Model ◽  
Reconstruction Method ◽  
3D Point Clouds ◽  
Surface Models ◽  
Structural Surface ◽  
Better Than

Three-dimensional (3D) digital technology is essential to the maintenance and monitoring of cultural heritage sites. In the field of bridge engineering, 3D models generated from point clouds of existing bridges is drawing increasing attention. Currently, the widespread use of the unmanned aerial vehicle (UAV) provides a practical solution for generating 3D point clouds as well as models, which can drastically reduce the manual effort and cost involved. In this study, we present a semi-automated framework for generating structural surface models of heritage bridges. To be specific, we propose to tackle this challenge via a novel top-down method for segmenting main bridge components, combined with rule-based classification, to produce labeled 3D models from UAV photogrammetric point clouds. The point clouds of the heritage bridge are generated from the captured UAV images through the structure-from-motion workflow. A segmentation method is developed based on the supervoxel structure and global graph optimization, which can effectively separate bridge components based on geometric features. Then, recognition by the use of a classification tree and bridge geometry is utilized to recognize different structural elements from the obtained segments. Finally, surface modeling is conducted to generate surface models of the recognized elements. Experiments using two bridges in China demonstrate the potential of the presented structural model reconstruction method using UAV photogrammetry and point cloud processing in 3D digital documentation of heritage bridges. By using given markers, the reconstruction error of point clouds can be as small as 0.4%. Moreover, the precision and recall of segmentation results using testing date are better than 0.8, and a recognition accuracy better than 0.8 is achieved.

Seismic and geodetic response to crustal deformation in Krísuvík volcanic system, southwest Iceland

2020 ◽  
Author(s):  
Revathy M. Parameswaran ◽  
Ingi Th. Bjarnason ◽  
Freysteinn Sigmundsson
Keyword(s):  
Stress Field ◽  
Crustal Deformation ◽  
High Energy ◽  
Strike Slip ◽  
Normal Faults ◽  
Seismic Zone ◽  
The South ◽  
The West ◽  
Volcanic System ◽  
Geothermal Activity

<p>The Reykjanes Peninsula (RP) is a transtensional plate boundary in southwest Iceland that marks the transition of the Mid-Atlantic Ridge (MAR) from the offshore divergent Reykjanes Ridge (RR) in the west to the South Iceland Seismic Zone (SISZ) in the east. The seismicity here trends ~N80°E in central RP and bends to ~N45°E at its western tip as it joins RR. Seismic surveys, geodetic studies, and recent GPS-based kinematic models indicate that the seismic zone is a collection of strike-slip and normal faults (e.g., Keiding et al., 2008). Meanwhile, the tectonic processes in the region also manifest as NE-SW trending volcanic fissures and normal faults, and N-S oriented dextral faults (e.g., Clifton and Kattenhorn, 2006). The largest of these fissure and normal-fault systems in RP is the Krísuvík-Trölladyngja volcanic system, which is a high-energy geothermal zone. The seismicity here predominantly manifests RP’s transtentional tectonics; however, also hosts triggered events such as those following the 17 June 2000 Mw6.5 earthquake in the SISZ (Árnadottir et al., 2004) ~80 km east of Krísuvík. Stress inversions of microearthquakes from 1997-2006 in the RP indicate that the current stress state is mostly strike-slip with increased normal component to the west, indicating that the seismicity is driven by plate diverging motion (Keiding et al., 2009). However, the geothermal system in Krísuvík is a potential secondary source for triggered seismicity and deformation. This study uses seismic and geodetic data to evaluate the activity in the Krísuvík-Trölladyngja volcanic system. The seismic data is used to identify specific areas of focused activity and evaluate variations in the stress field associated with plate motion and/or geothermal activity over space and time. The data used, within the time period 2007-2016, was collected by the the South Icelandic Lowland (SIL) seismic network operated and managed by the Iceland Meterological Office (IMO). Furthermore, variations in seismicity are compared to crustal deformation observed with TerraSAR-X images from 2009-2019. Crustal changes in the Krísuvík area are quantified to develop a model for corresponding deformation sources. These changes are then correlated with the stress-field variations determined with seismic analysis.</p>

scholarly journals Application of aerial photogrammetric technology for determination and parametrization of areas affected by extraction of raw materials

Baltica ◽  
2019 ◽  
Vol 32 (2) ◽  
pp. 202-209
Author(s):  
Audrius Armanavičius ◽  
Jonas Satkūnas
Keyword(s):  
Coastal Erosion ◽  
Raw Materials ◽  
Mineral Resources ◽  
Field Surveys ◽  
Mining Sites ◽  
Aerial Photogrammetry ◽  
Geological Processes ◽  
Significant Damage ◽  
Special Project ◽  
First Time

Extraction of mineral raw materials is increasing due to economic development and must be a normal process under due control and environmental supervision. However, there are a number of sites where the exploitation was stopped and mining sites were abandoned without proper restoration. Also, there are sites where mineral resources were or are extracted illegally thus making significant damage to the environment and economy. In order to collect information on land impacted by mining and extraction activities, for the first time a special project was carried out for the entire territory of Lithuania. The project consisted of gathering of information on damaged areas from various sources, field surveys and systematization of collected data. In order to obtain volumetric data, a special technology of aerial photogrammetry was developed and successfully applied. It was detected that the number of damaged sites > 0.3 ha reached up to 3,300. It is estimated that a total amount of illegally extracted minerals in last 15–20 years could be up to 15 million m3. The aerial photogrammetry was proved as a relevant technology and this could be applied for the control of the restoration of damaged land as well as for the monitoring of hazardous geological processes, e.g. coastal erosion, karst.

scholarly journals THERMAL 3D MODELS ENHANCEMENT BASED ON INTEGRATION WITH VISIBLE IMAGERY

2019 ◽  
Vol XLII-4/W18 ◽  
pp. 263-269
Author(s):  
F. Dadras Javan ◽  
M. Savadkouhi
Keyword(s):  
High Resolution ◽  
Thermal Imaging ◽  
Point Cloud ◽  
Point Clouds ◽  
3D Models ◽  
Thermal Modelling ◽  
Surface Models ◽  
Geometric Quality ◽  
Imaging Sensors ◽  
Visible Imagery

Abstract. In the last few years, Unmanned Aerial Vehicles (UAVs) are being frequently used to acquire high resolution photogrammetric images and consequently producing Digital Surface Models (DSMs) and orthophotos in a photogrammetric procedure for topography and surface processing applications. Thermal imaging sensors are mostly used for interpretation and monitoring purposes because of lower geometric resolution. But yet, thermal mapping is getting more important in civil applications, as thermal sensors can be used in condition that visible sensors cannot, such as foggy weather and night times which is not possible for visible cameras. But, low geometric quality and resolution of thermal images is a main drawback that 3D thermal modelling are encountered with. This study aims to offer a solution for to fixing mentioned problem and generating a thermal 3D model with higher spatial resolution based on thermal and visible point clouds integration. This integration leads to generate a more accurate thermal point cloud and DEM with more density and resolution which is appropriate for 3D thermal modelling. The main steps of this study are: generating thermal and RGB point clouds separately, registration of them in two course and fine level and finally adding thermal information to RGB high resolution point cloud by interpolation concept. Experimental results are presented in a mesh that has more faces (With a factor of 23) which leads to a higher resolution textured mesh with thermal information.

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