Tectonique et venues volcaniques en contexte de collision, exemple du massif néogène du Siroua (Atlas Marocain) : effets combinés d'une transformante et de la suture panafricaine

2001 ◽  
Vol 38 (3) ◽  
pp. 411-425
Author(s):  
J Chorowicz ◽  
A Emran ◽  
E M Alem
Keyword(s):  
Late Miocene ◽  
Active Faults ◽  
Suture Zone ◽  
Open Fractures ◽  
Magma Ascent ◽  
African Plate ◽  
Regional Deformation ◽  
Digital Elevation ◽  
Elevation Model ◽  
Convergence Trend

The Late Miocene – Early Pliocene Siroua strato-volcano is made of particular hyperalkaline rocks. It lies between the High-Atlas and the Anti-Atlas, in a collisional zone related to the continental subduction of the African plate under the Moroccan Meseta. Our field observations and analyses of SPOT, Landsat-MSS, and DEM (digital elevation model) imagery have permitted mapping of faults, joints, and volcanic edifices. The elongate shape of volcanoes and linear clusters of adjacent edifices, together with their relationships with faults, show that magma ascent was favored by tectonic crustal scale open fractures, essentially tension fractures, tail-cracks, and open faults. These fractures, together with other nonvolcanic, narrow, NNE-striking troughs, provide valuable information on the regional deformation since the Late Miocene. The shortening–extension type strain, which is responsible for the open fractures, is situated near the Azdem transform, a zone of active faults striking NNE, parallel to the convergence trend. The transform links two segments of the "Accident Sud-Atlasique," which constitute the border between the Moroccan Meseta and the African plate. The magma seems to originate from the lithospheric mantle, but asthenospheric material had previously migrated upward along the Panafrican suture zone. This mixed magma finally was transferred to the surface as a result of the onset of the open fractures prior to fault motions. The Siroua volcanic activity results from the conjunction of (1) a Panafrican suture zone and (2) a zone of open fractures due to "strike-slip" strain near a local transform inside the area of collision.

Treatise on the tectonic geomorphology of active faults: The significance of using a universal digital elevation model

2018 ◽  
Vol 116 ◽  
pp. 241-252 ◽  
Author(s):  
Ioannis K. Koukouvelas ◽  
Vasiliki Zygouri ◽  
Konstantinos Nikolakopoulos ◽  
Sotirios Verroios
Keyword(s):  
Digital Elevation Model ◽  
Active Faults ◽  
Tectonic Geomorphology ◽  
Digital Elevation ◽  
Elevation Model

scholarly journals Identifikasi Sesar Aktif di Pulau Bali dengan Menggunakan Data Pemetaan Geologi Permukaan dan Morfologi Tektonik

2021 ◽  
Vol 35 (1) ◽  
pp. 45
Author(s):  
Hurien Helmi ◽  
Gayatri Indah Marliyani ◽  
Siti Nur’aini
Keyword(s):  
Hazard Analysis ◽  
Active Faults ◽  
Fault System ◽  
Normal Faults ◽  
Earthquake Hazards ◽  
Digital Elevation ◽  
Shallow Earthquakes ◽  
Lineament Analysis ◽  
Elevation Model ◽  
Back Arc

Pulau Bali dan sekitarnya berada dekat dengan zona subduksi sehingga rawan terhadap bencana gempa bumi. Struktur utama yang menyebabkan gempa bumi di Bali umumnya berada di zona subduksi di bagian selatan dan di zona sesar naik belakang busur di utara yang dikenal dengan sesar naik Flores. Selain potensi gempa dari kedua zona sesar ini, gempa yang berasal dari zona sesar di darat juga bisa menimbulkan bahaya yang signifikan. Penelitian ini bertujuan untuk melakukan pemetaan sesar aktif di darat dengan menggunakan kombinasi antara metode penginderaan jauh dengan survey lapangan. Data yang digunakan sebagai peta dasar adalah data digital elevation (DEM) model DEMNAS beresolusi 8 m serta data DEM beresolusi 0.5 m yang dihasilkan melalui proses fotogrametri dari foto udara. Analisis kelurusan menunjukkan adanya pola berarah baratlaut-tenggara dan timulaut-baratdaya. Validasi di lapangan menunjukkan bahwa kelurusan ini berasosiasi dengan keberadaan sesar-sesar geser, sesar oblique dan sesar turun. Sesar-sesar ini memotong batuan berumur Kuarter hingga endapan masa kini. Selain itu, data sebaran seismisitas menunjukkan adanya zona kegempaan dangkal yang berada pada area di sekitar kelurusan yang dipetakan. Kedua indikator ini menunjukkan bahwa sesar-sesar yang teridentifikasi dalam penelitian ini bisa dikategorikan sebagai sesar aktif. Hasil dari penelitian ini memberikan pemahaman baru mengenai geometri sesar aktif yang ada di Pulau Bali dan potensi kegempaan di masa yang akan datang yang memberikan kontribusi terhadap upaya mitigasi bencana gempa bumi di Pulau Bali. Bali and its surrounding region are located within proximity of the Sunda-Banda subduction zone making it prone to earthquake hazards. The structures that caused earthquakes in Bali are mainly from the front subduction faults and from the back-arc thrust fault known as the Flores Fault. In addition, earthquakes are frequently occur in the inland fault system. This study aims to map the inland active faults in Bali using a combination of remotely-based and field-mapping methods. We use the 8-m resolution digital elevation model (DEM) of DEMNAS and the 0.5 m resolution DEM from photogrammetry processing of aerial photo as our base maps. Our lineament analysis identifies northwest-southeast and northeast-southwest lineaments. Our field observation confirms these lineaments to be associated with strike-slip, oblique and normal faults. These faults dissect Quarternary to recent rock units. In addition, seismicity data indicate the occurrence of shallow earthquakes in the vicinity of these structures. All of these indicate that these structures are active. Results from this study provide a new understanding of the inland active fault geometry in Bali, useful in the seismic hazard analysis and may contribute to the earthquake mitigation efforts in Bali.   

scholarly journals Surface rupture and characteristics of a fault associated with the 2011 and 2016 earthquakes in the southern Abukuma Mountains, northeastern Japan, triggered by the Tohoku-Oki earthquake

2019 ◽  
Vol 71 (1) ◽  
Author(s):  
Keitaro Komura ◽  
Kotaro Aiyama ◽  
Takahiro Nagata ◽  
Hiroshi P. Sato ◽  
Akihiro Yamada ◽  
...  
Keyword(s):  
Active Faults ◽  
Aerial Photographs ◽  
Japan Trench ◽  
Normal Faults ◽  
Interferometric Synthetic Aperture Radar ◽  
Northeastern Japan ◽  
Digital Elevation ◽  
Geomorphic Features ◽  
Surface Ruptures ◽  
Elevation Model

Abstract The 2011 Tohoku-Oki offshore subduction earthquake (Mw 9.0) triggered many normal-type earthquakes inland in northeastern Japan. Among these were two very similar normal-faulting earthquakes in 2011 (Mw 5.8) and 2016 (Mw 5.9), which created surface ruptures along the newly named Mochiyama fault within the southern Abukuma Mountains, northeastern Japan, where no active faults had been previously mapped by interpretation of aerial photographs. We conducted field surveys in this area immediately after both earthquakes, and we performed trench excavations and observations of fault fracture zones after the 2016 event. These activities were complemented by an interferometric synthetic aperture radar analysis that mapped the areas of deformation and locations of surface discontinuities for both events. The combined results document the coseismic behavior of the Mochiyama fault during both events. Subtle tectonic geomorphic features associated with the fault were evident in a lidar digital elevation model of the area, and layered structures of gouge were documented in the field. These lines of evidence indicate repeated activity at shallow crustal levels and the possibility of Quaternary activity. In addition, our trench excavations revealed at least one faulting event before 2011. Our comparison of paleoseismic records on this and two other normal faults in the Abukuma Mountains suggests that great earthquakes in the Japan Trench supercycle of 500–700 years do not consistently trigger ruptures on these faults, and the case of 2011, in which the Tohoku-Oki megathrust earthquake triggered all three faults, is a rare occurrence.

scholarly journals Analisis Potensi Genangan Tsunami dan Penentuan Jalur Evakuasi Berbasis Sistem Informasi Geografis di Desa Daruba Pantai – Kabupaten Pulau Morotai

2021 ◽  
Vol 9 (1) ◽  
pp. 79-91
Author(s):  
Mohammad Ridwan Lessy ◽  
Nurhalis Wahiddin ◽  
Jefry Bemba ◽  
Marwis Aswan
Keyword(s):  
Digital Elevation Model ◽  
Active Faults ◽  
Safety Zone ◽  
Tsunami Inundation ◽  
Inundation Area ◽  
Digital Elevation ◽  
Study Results ◽  
Neighborhood Unit ◽  
Elevation Model ◽  
Evacuation Route

Tsunami is one of the catastrophic events that threatened coastal areas in Morotai Island Regency. This is partly because the location of the regency is among several active faults. Therefore, the study aims to analyze the tsunami inundation area and determine a tsunami evacuation route in Daruba Pantai Village, South Morotai District. This study begins with the preparation of a digital elevation model and is compiled with other related maps to produce the tsunami inundation area at the study site. The study results show that a tsunami can hit 176.65 ha, with the disastrous and dangerous category being 5.02% and 0.66%. Meanwhile, specifically for the Daruba Pantai Village area with an area of 60.59 ha, the disastrous and dangerous categories are 10.72% and 1.30%, and the safe category is 36.61% and secure 23.07%. Furthermore, the preparation of the evacuation route is based on the scenario that residents from each zone of both the Neighborhood Unit (RT) and Community Unit (RW) are directed to follow the evacuation path to move towards the temporary shelter point and towards the safety zone.

STUDY OF THE LANDSLIDE MORPHOLOGY BASED ON GNSS DATA AND AIRBORNE SOUNDING (ON THE EXAMPLE OF A SECTION OF THE PROTVA RIVER VALLEY)

2018 ◽  
Vol 12 (5-6) ◽  
pp. 50-57 ◽  
Author(s):  
I. S. Voskresensky ◽  
A. A. Suchilin ◽  
L. A. Ushakova ◽  
V. M. Shaforostov ◽  
A. L. Entin ◽  
...  
Keyword(s):  
Digital Elevation Model ◽  
Geodetic Network ◽  
Aerial Survey ◽  
River Valley ◽  
Ease Of Use ◽  
Digital Elevation ◽  
Loose Deposits ◽  
Positioning Method ◽  
Landslide Body ◽  
Elevation Model

To use unmanned aerial vehicles (UAVs) for obtaining digital elevation models (DEM) and digital terrain models (DTM) is currently actively practiced in scientific and practical purposes. This technology has many advantages: efficiency, ease of use, and the possibility of application on relatively small area. This allows us to perform qualitative and quantitative studies of the progress of dangerous relief-forming processes and to assess their consequences quickly. In this paper, we describe the process of obtaining a digital elevation model (DEM) of the relief of the slope located on the bank of the Protva River (Satino training site of the Faculty of Geography, Lomonosov Moscow State University). To obtain the digital elevation model, we created a temporary geodetic network. The coordinates of the points were measured by the satellite positioning method using a highprecision mobile complex. The aerial survey was carried out using an unmanned aerial vehicle from a low altitude (about 40–45 m). The processing of survey materials was performed via automatic photogrammetry (Structure-from-Motion method), and the digital elevation model of the landslide surface on the Protva River valley section was created. Remote sensing was supplemented by studying archival materials of aerial photography, as well as field survey conducted immediately after the landslide. The total amount of research results made it possible to establish the causes and character of the landslide process on the study site. According to the geomorphological conditions of formation, the landslide refers to a variety of landslideslides, which are formed when water is saturated with loose deposits. The landslide body was formed with the "collapse" of the blocks of turf and deluvial loams and their "destruction" as they shifted and accumulated at the foot of the slope.

Urban Flood Mapping

2017 ◽  
Author(s):  
Indra Riyanto ◽  
Lestari Margatama
Keyword(s):  
Natural Disasters ◽  
Satisfying Condition ◽  
Three Dimensions ◽  
Urban Flood ◽  
Digital Elevation ◽  
Elevation Data ◽  
Recent Occurrence ◽  
Elevation Model ◽  
Digital Elevation Model Data ◽  
Potential Area

The recent degradation of environment quality becomes the prime cause of the recent occurrence of natural disasters. It also contributes in the increase of the area that is prone to natural disasters. Flood history data in Jakarta shows that flood occurred mainly during rainy season around January – February each year, but the flood area varies each year. This research is intended to map the flood potential area in DKI Jakarta by segmenting the Digital Elevation Model data. The data used in this research is contour data obtained from DPP–DKI with the resolution of 1 m. The data processing involved in this research is extracting the surface elevation data from the DEM, overlaying the river map of Jakarta with the elevation data. Subsequently, the data is then segmented using watershed segmentation method. The concept of watersheds is based on visualizing an image in three dimensions: two spatial coordinates versus gray levels, in which there are two specific points; that are points belonging to a regional minimum and points at which a drop of water, if placed at the location of any of those points, would fall with certainty to a single minimum. For a particular regional minimum, the set of points satisfying the latter condition is called the catchments basin or watershed of that minimum, while the points satisfying condition form more than one minima are termed divide lines or watershed lines. The objective of this segmentation is to find the watershed lines of the DEM image. The expected result of the research is the flood potential area information, especially along the Ciliwung river in DKI Jakarta.

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