Hummock alignment in Japanese volcanic debris avalanches controlled by pre-avalanche slope of depositional area

Yoshida, Hidetsugu

doi:10.1016/j.geomorph.2014.06.024

Cited by 18 publications

(20 citation statements)

References 18 publications

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“…6b). As suggested by the displacement angles, some hummocks with displaced orientations 5 indicate a partial compressional regime of the debris avalanche, while the other, majority of hummocks without large displacements indicate an extensional regime of the debris avalanche due to the rapid northward flow through the valley (Paguican et al, 2014;Yoshida, 2014).…”

Section: Debris Avalanche and Formation Of Hummocksmentioning

confidence: 92%

“…Fig. 3 shows the definition of the displacement angle of the major axis of a hummock: the angle between the main direction of the valley-filling DAD and the major axis 20 (Yoshida, 2014). The main direction of the DAD in the study site is the north.…”

Section: Rpas-based Sfm-mvs Photogrammetry and Hummock Mappingmentioning

confidence: 99%

“…Within the domain of debris avalanche deposits (DAD), 5 hummocks often have clear boundaries and are readily identifiable, thus providing a chance to carry out the robust size and shape analysis (Mizuno, 1958;Hashimoto et al, 1979). Such the morphology of hummocks, located on the surface of DADs, can be used to estimate the characteristics of the debris avalanche, i.e., the kinematics of the sliding mass of the sector collapse (Dufresne and Davies, 2009;Koarai et al, 2008;Yoshida and Sugai, 2010;Yoshida, 2012Yoshida, , 2013Yoshida, , 2014Yoshida et al, 2012). Although sedimentological investigations of the internal structures of DADs often provide insights into the 10 transport mechanisms (e.g., Glicken, 1996;Bernard et al, 2008;Shea et al, 2008), geomorphological or geometrical analyses of the surficial morphology of DADs including hummocks can also provide estimations on the size and processes of the debris avalanche.…”

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confidence: 99%

“…Because the typical size of hummocks is on the order of tens to hundreds of meters, stereo-paired aerial photographs 20 have often been used for the detection and morphological analysis of hummocks (Glicken, 1996;Yoshida, 2012Yoshida, , 2013Yoshida, , 2014Yoshida and Sugai, 2010;Yoshida et al, 2012). High-resolution topographic data by airborne laser scanning (ALS), i.e., 1-5 m resolution digital elevation models (DEM), can also be used for such analysis (e.g., Hayakawa et al, in press).…”

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confidence: 99%

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Morphological analysis of hummocks in debris avalanche deposits around Mt Erciyes, central Turkey

Hayakawa

Yoshida

Obanawa³

et al. 2017

Preprint

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Debris avalanche caused by the sector collapse of a volcanic mountain often forms characteristic depositional 15 landforms including hummocks. Not only sedimentological but also geomorphological analyses of debris avalanche deposits (DAD) are crucial to clarify the size, mechanisms, and processes of the debris avalanche. We investigate the morphology of hummocks newly identified in the DAD at the north-eastern flank of Mt. Erciyes in Kayseri, central Turkey, likely formed in the late Pleistocene. Using a remotely piloted aircraft system (RPAS) and the structure-from-motion multi-view stereo photogrammetry (SfM), we obtained high-definition digital elevation model (DEM) and orthorectified image of the DAD 20 surface with hummocks. Detailed geometric features of the hummocks are investigated using the RPAS-derived highdefinition DEM. The source volume of the DAD was also estimated by reconstructing the original shape of the mountain body using a lower-resolution satellite-based DEM. For this, topographic cross sections are examined based on the slopes around the scar that are regarded as the remnant topography preserved since the sector collapse. The spatial distribution of hummocks shows an unusual pattern regarding the distance-size relationships, i.e., anomalously concentrated in a certain 25 distance from the source. The hummocks are found to be aligned toward the flow direction of the debris avalanche, suggesting the extensional regime of the debris avalanche. These facts indicate that this debris avalanche did not follow the typical flow type of debris avalanches observed in the other cases. Instead, the topographic constraints by former caldera wall and fault-induced lineaments could have strongly affected the flow course and pattern in this particular case: The preexisting caldera wall topography could have acted as the topographic barriers for the debris avalanche to force the initial 30 flow to turn northward, and the flow regime to be once compressional followed by extensional at the narrow and steepened outlet valley. Also, the estimated volume of the DAD 12-15  10 8 m 3 gives its mean thickness of 60-75 m, which is much deeper than the reported cases of other DADs. This suggests that the debris avalanche could have flown down to the far downstream areas from the presently-observed limit of the DAD extent. Assessments of the DAD including the results of this study can provide further insights into the risk and mitigation of potential disasters in the study area. 35

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Section: Debris Avalanche and Formation Of Hummocksmentioning

confidence: 92%

Section: Rpas-based Sfm-mvs Photogrammetry and Hummock Mappingmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Morphological analysis of hummocks in debris avalanche deposits around Mt Erciyes, central Turkey

Hayakawa

Yoshida

Obanawa³

et al. 2017

Preprint

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“…The geomorphometric approach is powerful to characterize the DAD's topography [4]. The hummocks morphology can be analyzed using a qualitative and quantitative approach in order to: (i) interpret the mechanism of its formation, (ii) calculate the avalanche flow direction, and (iii) trace the magnitude of the sector collapse [7]. For analyzing the origin of the sector collapse and its mode of emplacement, ten variables have been identified, i.e.…”

Section: Introductionmentioning

confidence: 99%

Hummocky terrain of the Kalibabak debris avalanche deposit, Lombok Island, Indonesia

et al. 2020

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The debris avalanche deposit (DAD) coverage can drastically modify the surrounding landscape of volcanoes. DAD can be distinguished by hummocky irregular surface, jigsaw fissure, and mixing horse-shoe shape. Due to its particular shape of a hummock, the topography can be easily identified using DEM (Digital Elevation Model) and satellite imagery. The aim of this study is to characterize hummocky terrain in Lombok Island, which is located in the Kalibabak formation on the Geological map through the geomorphic approach. Hummocky terrain in this study are analyzed using DEM data from DEMNAS (DEM Nasional: 0.27-arcsecond resolution). Our study of this DAD encompasses seven variables, namely H/L ratio, numbers hummocks, distance to source, slope, area (size), relative height, topographic section, and hummock-spreading shape. A minimum of 756 hills derived from this DEM are considered as hummocks from this DAD, which extends ~18 km (NS) and ~25 km (WE) in the central part of Lombok Island. With an area of ~200 km2 and a volume estimated around 8.8 km3, the Kalibabak DAD is more than three times larger than the one of the Mount St-Helens in 1980. The morphology of hummocky terrain is bounded by a sudden change of slope, which is indicated by a river confluence. Average hummock size is 2.7 ha and average distance between each hummock is 150 m to 300 m. The hummocks are characterized by steep slopes (25 % to 45 %) at the boundary to colluvium plain (debris deposit), which makes them easy to identify using DEM. Hummocks spreading distribution forms a conical-like shape with a H/L ratio of 0.13. The spreading distribution shape, the H/L and V/L ratios are useful as an input for reconstructing the mechanism of debris avalanche emplacement.

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Rock Avalanches in the Tibetan Plateau of China

Wang,

Cheng,

Lin

et al. 2023

Progress in Landslide Research and Technology

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China is a country with high mountainous areas widely distributed, which is characterized by high reliefs, intensive tectonic activity, fragile ecological environments, etc. Under such particular background, rock avalanches, as one of the most threatening geological disasters in the high mountainous regions, have drawn much scientific interest because of their sudden occurrence, huge volumes (>106 m3), high velocities (>20 m/s), and extremely low Fahrböschung (typically 0.1 to 0.3) with destructive disasters caused. Focusing on the Tibetan Plateau of China, spatial distribution of rock avalanches in its certain area was conducted, hoping to provide insights into the controlling factors of rock avalanches’ formation. Furthermore, several typical rock avalanches were investigated in detail based on remote sensing analysis, mapping of fixed wing unmanned aerial vehicle and detailed field investigations. It is reached that toreva blocks, transverse and longitudinal ridges, ridges separated by conjugate troughs, and hummocks are common and widely distributed surficial landforms in rock avalanche deposits, which usually display in a clear sequential distribution. In the cross-section, a series of internal sedimentary structures, including jigsaw structures, inner shear zones, diapiric structures, convoluted laminations, faults, etc., were identified. Based on these detailed geological features, the possible emplacement processes and mechanisms are discussed to provide insights into the extremely high mobility of rock avalanches.

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Hummock alignment in Japanese volcanic debris avalanches controlled by pre-avalanche slope of depositional area

Cited by 18 publications

References 18 publications

Morphological analysis of hummocks in debris avalanche deposits around Mt Erciyes, central Turkey

Morphological analysis of hummocks in debris avalanche deposits around Mt Erciyes, central Turkey

Hummocky terrain of the Kalibabak debris avalanche deposit, Lombok Island, Indonesia

Rock Avalanches in the Tibetan Plateau of China

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