Appraisal of active tectonics in Hindu Kush: Insights from DEM derived geomorphic indices and drainage analysis

Abstract

Landscapes in tectonically active Hindu Kush (NW Pakistan and NE Afghanistan) result from a complex integration of the effects of vertical and horizontal crustal block motions as well as erosion and deposition processes. Active tectonics in this region have greatly influenced the drainage system and geomorphic expressions. The study area is a junction of three important mountain ranges (Hindu Kush-Karakorum-Himalayas) and is thus an ideal natural laboratory to investigate the relative tectonic activity resulting from the India-Eurasia collision. We evaluate active tectonics using DEM derived drainage network and geomorphic indices hypsometric integral (HI), stream-length gradient (SL), fractal dimension (FD), basin asymmetry factor (AF), basin shape index (B s ), valley floor width to valley height ratio (Vf ) and mountain front sinuosity (S mf ).The results obtained from these indices were combined to yield an index of relative active tectonics (IRAT) using GIS. The average of the seven measured geomorphic indices was used to evaluate the distribution of relative tectonic activity in the study area. We defined four classes to define the degree of relative tectonic activity: class 1 __ very high (1.0 IRAT < 1.3); class 2 __ high (1.3 ! IRAT < 1.5); class GEOSCIENCE FRONTIERS journal homepage: www.elsevier.com/locate/gsf GEOSCIENCE FRONTIERS 3(4) (2012) 407e428 3dmoderate (1.5 ! IRAT < 1.8); and class 4dlow (1.8 ! IRAT). In view of the results, we conclude that this combined approach allows the identification of the highly deformed areas related to active tectonics. Landsat imagery and field observations also evidence the presence of active tectonics based on the deflected streams, deformed landforms, active mountain fronts and triangular facets. The indicative values of IRAT are consistent with the areas of known relative uplift rates, landforms and geology. ª 2011, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.

Assessment of Geomorphic Processes and Active Tectonics in Con Voi Mountain Range Area (Northern Vietnam) Using the Hypsometric Curve Analysis Method

“…Convex hypsometric curves are typical of a youthful stage; S-shaped curves are related to a maturity stage, and concave curves are indicative of a peneplain stage (Strahler, 1957;Gardner et al, 1990;Delcaillau et al, 1998;Keller and Pinter., 2002; (Figure 3). Strahler, 1952;Pérez-Peña et al, 2009;Mahmood and Gloaguen, 2012) A simple way to characterize the shape of the hypsometric curve for a given drainage basin is to calculate its hypsometric integral (HI). The integral is defined as the area under the hypsometric curve and can be calculated (Keller and Pinter, 2002):…”

“…The HC index is one of the geomorphic indices that has been considered as a powerful tool for quantifying the topographic features and differentiate zones deformed by active tectonics (Keller and Pinter, 2002;Chel et al, 2003;Pérez-Peña et al, 2009;Pedrera et al, 2009;Mahmood and Gloaguen, 2012). However, in Vietnam, this is the first time the method is adopted for the assessment of the active tectonics in the Lo River fault zone and the Tam Dao area (Ngo et al, 2016), but statistical moments of the hypsometric curve has not been analyzed and assessed.…”

Relative tectonics and debris flow hazards in the Beijing mountain area from DEM-derived geomorphic indices and drainage analysis

“…The occurrence of a debris flow is mostly influenced by local topographical characteristics, active tectonics and rainfall (Maroukian et al, 2008). Although mainly controlled by tectonics (Mahmood and Gloaguen, 2012), the former two factors can provide the basis for occurrence of debris flows (Wadge, 1994;Anbalagan and Singh, 1996).…”

“…These researchers concluded that relatively high potentials of active tectonics are associated with the indicative values of the IRAT. Mahmood and Gloaguen (2012) used seven geomorphic indices to compute the IRAT using GIS at the Hindu Kush, Karakorum, and Himalayas ranges. The indicative values of the IRAT are consistent with known uplift rates, landform characteristics and geology.…”

Active Tectonics Revealed by River Profiles along the Puqu Fault

“…Several methods have been proposed to extract river profiles and channel parameters from DEM. For example, Snyder et al [19] and Kirby and Whipple [21] have developed a group of built-in functions in ARC/INFO to create flow accumulation arrays and delineate drainage basins; Mahmood and Gloaguen [26] calculated the indices of relative active tectonics (IRAT) in the Geography Information System (GIS) from a DEM in Hindu Kush region. In addition, scientific programming languages such as Matlab and SAS scripts were integrated in GIS to color-code stream profiles by their steepness and concavity indices: Shahzad et al [22] have developed the package TecDEM using MATLAB for drainage network partition and river profile analysis from DEM and this package was also used by Vezzoli et al [27] to extract the fluvial network in Western Greater Caucasus.…”