On the possibility of reservoir-induced seismicity in the Garhwal Himalaya

Chander, R., 1991. On the possibility of reservoir-induced seismicity in the Garhwal Himalaya. Eng. Geol., 30: 393–399.

It is argued from a brief review of available evidence that the possibility of reservoir-induced seismicity (RIS) in the Himalaya as a whole cannot be ruled out at the present time. On the other hand, a review of recent local investigations of small earthquakes ( m_b less than 5) and teleseismic investigations of moderate earthquakes (m_b between 5 and 6, mainly) occurring in the Garhwal segment of the Alpide-Himalayan seismic belt provides evidence that RIS in the region can be anticipated. While their epicentral belts coincide geographically, the estimated focal depths of small and moderate earthquakes of the Garhwal Himalaya are in the ranges of 0–14 and 10–20 km, respectively. Small earthquakes occur by reactivation of strike-slip and reverse faults and moderate earthquakes occur on thrust faults. Elsewhere in the world, RIS has been observed most often in the crust at the depths where small earthquakes have been observed in the Garhwal Himalaya. In addition, RIS has been experienced during the impoundment of reservoirs in strike-slip and reverse fault environments, while theoretical analyses indicate that, if suitably located in relation to the reservoir, even a thrust fault may be destabilised by impoundment.     

Great earthquakes,seismicity gaps and potential for earthquake disaster along the Himalaya plate boundary

Analysis of the space-time patterns of seismicity in the Himalaya plate boundary has established the existence of three seismic gaps:

• 1.(1) The “Kashmir gap” lying west of the 1905 Kangra earthquake;
• 2.(2) the “Central gap”, situated between the 1905 Kangra and the 1934 Bihar earthquakes;
• 3.(3) the “Assam gap” between the 1897 and 1950 Assam earthquakes.

This study has shown that the above great earthquakes were preceded as well as followed by long periods (⩾ 19 years) of decreased levels of seismic activity in the epicentral regions. Remarkable decrease in the seismicity following the year 1970 has been observed in the western half of the Central gap as well as in the Assam gap. Local seismic investigation in the Assam gap confirms this feature and the seismicity suggests the existence there of an asperity.The local seismic investigations in Garhwal Himalaya have shown that the small earthquakes are confined to the upper 6–8 km of the crust and may have strike-slip motions. These earthquakes occur in a region where teleseismically recorded events were few.     

Tectonics of the Central Crystallines of western Himalaya

The crystalline sheet of the Higher Himalaya, referred to as the Central Crystallines, is a continuous lithotectonic unit which can be traced from the River Kali of eastern Kumaun in the east to Sankoo in the Suru River valley of Kashmir in the west. The principal lithostratigraphic units of this zone are pelites, psammites, gneisses, amphibolites, migmatites and leucocratic granites. The rocks of this zone show progressive regional metamorphism of normal as well as reverse types, the metamorphic grade ranging from chlorite to sillimanite zone. The Main Central Thrust, which demarcates the southern boundary of the Central Crystallines, has brought the crystalline rocks to rest over the sediments of Deoban Group in Kumaun and Garhwal and over the Outer Crystallines (=Chail-Jutogh Nappe) in Himachal Pradesh. The evidence obtained from metamorphism, deformation and radiometric dating indicate that the Central Crystallines is an old Precambrian basement which has been reactivated during Caledonian and Alpine orogenic movements.     

Lithospheric structure and Mesozoic geodynamics of the eastern Central Asian orogen

The lithospheric structure of several marginal and interior units of the eastern Central Asian orogen has been explored in 2D geophysical models. The obtained constraints on effective parameters (density, resistivity, temperature) of lithospheric blocks and their boundaries allowed correlation of geophysical structures to tectonic settings. The geological and geophysical (including paleomagnetic) data were used jointly to model the present structure of the lithosphere along 126° E between 56° N and 40° N and to construct a palinspastic model of the same area for the latest Early Jurassic (175 Ma).     

Geodynamics and seismicity of the eastern part of Central Asia

Study of the geodynamics of the eastern part of Central Asia shows that the present-day tectonic activity of this territory is connected with its division into blocks limited by active faults and with the interaction among these blocks and with the neighboring lithospheric plates. The North China and South China platforms occupy most of this territory. The western boundary of the South China platform with Tibetan blocks is the most active. The energy volume increases up to 10¹⁰–10¹² J, and the earthquake magnitudes go up to 8–9 within this boundary. The interaction of Tibetan blocks with the Southeast China Block causes detachment and a clockwise turn of the upper layers of the Earth’s crust under the influence of the Hindustan indenter pressure.

     

Intraplate geodynamics and magmatism in the evolution of the Central Asian Orogenic Belt

The Central Asian Orogenic Belt (CAOB) was produced as a consequence of the successive closure of the Paleoasian Ocean and the accretion of structures formed within it (island arcs, oceanic islands, and backarc basins) to the Siberian continent. The belt started developing in the latest Late Neoproterozoic, and this process terminated in the latest Permian in response to the collision of the Siberian and North China continents that resulted in closure of the Paleoasian ocean (Metcalfe, 2006; Li et al., 2014; Liu et al., 2009; Xiao et al., 2010; Didenko et al., 2010). Throughout the whole evolutionary history of this Orogenic Belt, a leading role in its evolution was played by convergent processes. Along with these processes, an important contribution to the evolution of the composition and structure of the crust in the belt was made by deep geodynamic processes related to the activity of mantle plumes.Indicator complexes of the activity of mantle plumes are identified, and their major distribution patterns in CAOB structures are determined. A number of epochs and areas of intraplate magmatism are distinguished, including the Neoproterozoic one (Rodinia breakup and the origin of alkaline rock belt in the marginal part of the Siberian craton); Neoproterozoic–Early Cambrian (origin of oceanic islands in the Paleoasian Ocean); Late Cambrian–Early Ordovician (origin of LIP within the region of Early Caledonian structures in CAOB); Middle Paleozoic (origin of LIP in the Altai–Sayan rift system); Late Paleozoic–Early Mesozoic (origin of the Tarim flood-basalt province, Central Asian rift system, and a number of related zonal magmatic areas); Late Mesozoic–Cenozoic (origin of continental volcanic areas in Central Asia).Geochemical and isotopic characteristics are determined for magmatic complexes that are indicator complexes for areas of intraplate magmatism of various age, and their major evolutionary trends are discussed. Available data indicate that mantle plumes practically did not cease to affect crustal growth and transformations in CAOB in relation to the migration of the Siberian continent throughout the whole time span when the belt was formed above a cluster of hotspots, which is compared with the African superplume.     

Seismic strain in the Altai-Sayan active seismic area and elements of collisional geodynamics

Seismic strain estimated from about 900 earthquake mechanisms in the Altai-Sayan area indicates that the area evolves mainly under N-S compression caused by the India-Eurasia collision. Plastic flow in the mountains of the western and central Altai-Sayan area is controlled by convergence of aseismic rigid blocks, including the Dzungarian microplate, the Minusa basin, the Tuva basin, Uvs Nuur and other basins in the region of Great Lakes in Mongolia. Earthquake rupture follows the existing fault pattern. The pattern of rigid blocks and mountain ranges correlates well with upper mantle thermal heterogeneity as imaged by seismic tomography.Earthquake mechanisms in the presence of plate convergence depend on different factors. Slip geometry depends on focal depth at a given geodynamic regime, and the latter, in terms of the seismic process, is controlled by lateral (W-E) constraint. Reverse-slip earthquakes most often originate at shallow depths in regions of constrained compression, such as the Tien Shan, and strike slip is the dominant mechanism under non-constrained and moderately constrained compression. The direction of slip is governed by the parallel component of convergence and by the fault pattern. In regions of strain shadow, slip occurs mostly on normal planes, and shallow earthquakes have strike-slip mechanisms. The crust in the collisional region is divided into systems of rigid and plastic blocks (rheological structure) and of fault blocks (fault-block structure). The two types of systems coexist and determine the generally similar but specifically different features of local mass transfer.     

Fractal study of seismicity in order to characterize the various tectonic blocks of North-east Himalaya,India

North-eastern Himalaya is said to be one of the world most complex geological set-up with different kinds of seismotectonic systems. Region has experienced two of the world’s strongest earthquakes, such as Shillong earthquake of 1897 known as Assam earthquake and subsequent 1950 earthquake in Arunachal Pradesh, both of with magnitude of 8.7, and also several other strong earthquakes. Various techniques have been applied to understand the past strong earthquake mechanism as well as hazard estimation carried out for future earthquake. Fractal correlation dimension (D _c) is being used in this study with the seismicity for the period 1961 to recent for understanding the pattern of seismic hazard. The entire area has been divided into four major tectonic blocks, and each block event was divided into consecutive fifty events window for seeing spatiotemporal patterns. After comparing the patterns, we have identified that Block of Eastern Himalaya near Main Central Thrust, Main Boundary Thrust, north of Kopili lineament and Block of Shillong plateau near Dauki fault are having relatively intense clustering of events in recent times, which may be identified as the zones of most potential to have a strong event.     

Fuzzy-based method for landslide hazard assessment in active seismic zone of Himalaya

Landslides in Himalaya cause widespread damage in terms of property and human lives. It the present study, an attempt is made to derive information on causative parameters and preparation of landslide-susceptible map using fuzzy data integration in one of the seismically active region of Garhwal Himalaya that was recently devastated by a huge landslide. High-resolution remotely sensed data products acquired from Indian Remote Sensing Satellite before and after the landslide event were processed to improve interpretability and derivation of causative parameters. Spatial data sets such as lithology, rock weathering, geomorphology, lineaments, drainage, land use, anthropogenic factor, soil type and depth, slope gradient, and slope aspect were integrated using fuzzy gamma operator. The final map was reclassified in to five classes such as highly to lowly susceptible classes based on cumulative cutoff. The result shows around 72% of known landslide areas including the large Uttarkashi landslide in the high and very high susceptibility classes comprising of only 37% of the total area. The precipitation data from ground- and satellite-based observations were compared; the precipitation threshold and the role of seismic activity were analyzed for initiation of landslide.     

The Late Paleozoic geodynamics of the West Transbaikalian segment of the Central Asian fold belt

New data testifying to Late Paleozoic tectonometamorphic processes at the West Transbaikalian segment of the Central Asian Fold Belt have been obtained. Zircon dating (SHRIMP-II) of highly metamorphosed rocks showed that the processes took place at 295.3 ± 1.6 Ma. Based on these data, the Late Paleozoic ages of granitoids of the Angara–Vitim areal pluton (340–280 Ma) and some dike complexes in Transbaikalia (300–280 Ma), and the Late Paleozoic age of some carbonate-terrigenous strata dated earlier to the Early Paleozoic, we have substantiated the significant role of Hercynian tectogenesis in the consolidation of the regional continental crust. We have also shown that the Late Paleozoic endogenous events and accompanying sedimentation processes were related to the geodynamic conditions governed by the changing parameters of the subsidence of the Mongol-Okhotsk oceanic subduction slab beneath the Siberian continent. Changes in the slope and rate of the slab subsidence resulted in A-subduction conditions in the distal part of the suprasubduction plate, which led to the formation of accretion-collisional orogen and the Angara–Vitim areal pluton.     

Fractal study of seismicity in order to characterize the various tectonic blocks of North-east Himalaya,India

Three major projects initiated by the European Commission within its 7th Framework Programme that have studied the weather phenomena and their projections to the future in relation to their impacts and implications to the European transport systems have recently been concluded. All of the transport modes were covered, as well as all of the critical phenomena present within the European area. The three projects (that ran from 2009 and 2012) are as follows: (1) EWENT (Extreme Weather impacts on European Networks of Transport—www.ewent.vtt.fi); (2) ECCONET (Effects of climate change on the inland waterway networks—www.ecconet.eu); (3) WEATHER (Weather Extremes: Assessment of Impacts on Transport and Hazards for European Regions—www.weather-project.eu). In this Foreward to the Special Issue on “Vulnerability of Transportation to Extreme Weather and Climate Change,” the key results of the above three projects are addressed concisely, offering the reader a broader view of their findings; since some of these are enveloped in the research papers hosted in this volume, they will not be covered in detail. However, the rich output of these projects in the form of “Project Deliverables” and “Reports” is also an important source of information on the findings and results from these three projects which are publicly available on the projects’ Web sites. The purpose of this Foreward is to bring to the attention of the interested reader these sources and overview briefly some of the projects’ outcomes. Also, a short comparative discussion on selected findings is made, outlining agreements and disagreements between the projects.     

Multivariate statistical analysis of some recent volcanics from the Central Andes of Southern Peru

The application of Principal Component and Discriminant analysis to the major and minor oxides of recent volcanics from the Central Andes (S-Peru, N-Chile, Bolivia and Argentina) illustrates a variation in chemical composition related to geographical distribution, mainly in terms of TiO₂ and K₂O. A relationship between chemistry and distance from the Peru-Chile trench, dependent on P, Ti and Sr content of some cenozoic lavas from Southern Peru is also illustrated, by means of Multilinear Standardized Regressions and Partial Correlation analysis.

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Zusammenfassung Die Anwendung zweier statistischer Methoden (Principal Component und Discriminant Analysis) zur Erfassung der Oxidverteilung in den rezenten Vulkaniten der zentralen Anden (S-Peru, N-Chile, Bolivien und Argentinien) hat gezeigt, daß die Variation der chemischen Zusammensetzung, hauptsächlich bei TiO₂ und K₂O, abhängig von der geographischen Position der Ausbruchzentren ist.Eine Beziehung zwischen Geochemie und Entfernung vom Peru-Chile Tief-Seegraben für die rezenten Laven in S-Peru wird ferner mit multilinearen standardisierten Regressionen und Korrelationsanalysen, mit Schwerpunkt bei den Elementen P, Ti und Sr, aufgezeigt.

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Resume L'application de deux méthodes statistiques multivariées (Principal Component et Discriminant Analysis) à la distribution des éléments majeurs et mineurs dans les roches volcaniques récentes des Andes centrales (S-Pérou, N-Chili, Bolivie et Argentine) montre une variation de la composition chimique en fonction de la distribution géographique, surtout en ce qui concerne TiO₂ et K₂O.Une relation entre la variation de composition chimique de quelques laves récentes du Pérou du Sud et la distance du fossé océanique du Pérou-Chili est aussi montrée, à l'aide des Regressions Multilinéaires Standardisées et de l'Analyse de Corrélation partielle. Cette relation concerne spécialment les teneurs en P, Ti et Sr des laves étudiées.

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— Principal Component, Discriminant Analysis ( , , ) , . . . iO₂, K₂, . - . T Sr

     

Normal fault corrugation: implications for growth and seismicity of active normal faults

Large normal faults are corrugated. Corrugations appear to form from overlapping or en échelon fault arrays by two breakthrough mechanisms: lateral propagation of curved fault-tips and linkage by connecting faults. Both mechanisms include localized fault-parallel extension and eventual abandonment of relay ramps. These breakthrough mechanisms produce distinctive hanging wall and footwall geometries indicative of fault system evolution. From such geometries, we can estimate the positions of tilted relay ramps or ramp segments and ramp internal deformation in incompletely exposed or poorly imaged fault systems. We examine the evolution of normal fault corrugations at Fish Slough (California), Yucca Mountain (Nevada), and Pleasant Valley (Nevada), in the Basin and Range province. We discuss how evolution of the Pleasant Valley and Yucca Mountain systems relates to seismicity. For example, the 1915 Pleasant Valley earthquake produced four en échelon ruptures that appeared as overlapping segments of a single immature fault at depth. At Yucca Mountain, we argue that an en échelon array, which includes the Solitario Canyon and Iron Ridge faults, should be considered a single source, such that western Yucca Mountain could experience up to a M_w 6.9 earthquake compared to M_w 6.6 estimates for the largest individual segment.     

Quantitative Geomorphic Approach for Identifying Active Deformation in the Foreland Region of Central Indo-Nepal Himalaya

Geotectonics - Globally the remote sensing and geomorphometric analysis are frequently used for the assessment of tectonic activity. We used satellite-driven DEM data to analyze regional scale...     

Active faults, seismicity and recent fracturing in the lithosphere of the Baikal rift system

A map of major active faults has been constructed for the Baikal rift system (BRS). Recent active faults are identified using seismological data. The BRS seismicity of the past 40 years is statistically analyzed. Areas of a “stable” concentration of epicenters are revealed. On this basis, a zone of recent fracturing of the lithosphere is identified and its relation to active and developing faults of the BRS is analyzed. The zone of the lithosphere fracturing is a major tectonic structure, which controls both the recent seismic process and the reactivation of ancient faults. It is demonstrated that the available seismological data can provide a basis for a detailed classification of faults by degree of their tectonic activity. Regularities in the distribution of strong earthquakes along the zone of the recent fracturing of the lithosphere are established, as well as regularities in the distribution of strong and weak seismic events relative to transform and other faults. The degree of the fault reactivation is determined by their spatial closeness to the axial zone of the recent rupturing of the lithosphere.