Uttarkashi Earthquake Research Articles

Evaluation of Regional Demand Parameters for Design of Mid-high-rise Building Using Past Earthquake Records

Category of earthquake and distance from epicenter are the prime parameters that decide the demand on buildings for its engineering. As observed in past Bhuj earthquake of 2001 (7Mw), seventy buildings got severely damaged in Ahmedabad city which is located 250kms from the epicenter. Intensity index through observed damages fills the gap for the demand anticipations. Design of a building considering excitation frequency rather than just the zone factor is necessary to include effects of low frequency waves (e.g. Mexico-city). This paper shows the broad ways in which seismic demand can be obtained for performing PBD in Indian context. A mid-rise RC building is designed as per three standard code of practices (i.e. IS, ACI, EN) to provide seismic resistance. The anticipated demand levels are obtained using GMPEs (PEER), magnitude-intensity relations, micro-zonation study and NDMA hazard contours for 15 storey building in Ahmedabad. The highest capacity curve is for design using IS 1893 code and this building will survive earthquake having 0.22g PGA value. The magnitude-intensity-epicentral distance relation (Gutenberg et al, 1956) shows that the intensity of VII for Zone-III is not correct for Ahmedabad city and it shall be taken as VIII which is for Zone-IV (0.24g) as per zoning map of India. However, as per the micro-zonation study showing PGA of 0.18g for the city it can be said that building will survive the next earthquake of 7.0Mw in Bhuj. The damage to non-structural elements is evident from the NLTHA using matched response spectrum obtained using Uttarkashi and Chamoli earthquake records (COSMOS). It is suggested to use intensity-based response spectrum for design of mid-high-rise buildings in Ahmedabad city. Moreover, a local directive based on social and technology resilience shall be developed to provide design basis based on loss (%)-multiple hazard (PGA) matrix using the matching relations found in this paper. Design provisions and loss reduction strategy can only lead to sustainable infrastructure in cities planning for vertical development.

Seismic Performance of Multi Story Building with Different Base Isolators

Abstract: Earthquakes are one of nature's most dangerous hazards; throughout history, they have resulted in substantial loss of life and serious property damage, particularly to man-made structures. Seismic activity of large magnitude is a major source of risk for all types of constructions. We apply unique methodologies based on performance-based seismic design to protect structures from earthquakes. One way for reducing the influence of large-scale vibration created during an earthquake is the base isolation method. Seismic isolation can be used to give an efficient solution for a variety of seismic design difficulties according to well-established practices that have been examined by several researchers. It compares the performance of two types of isolators: Lead Rubber Bearing (LRB) and Friction Pendulum Bearing (FPB). G+12 R.C structure is taken in this study & Time History analysis is performed with ETABS software. Story drift and Story force are compared for the building with the base isolator against the building with the fixed base. In comparison with a fixed base building, parameters are changed in each direction due to the presence of an isolator. The analysis examines the characteristics and the effects of base isolation on structures with the Uttarkashi earthquake.

Development of Surface Level Seismic Hazard Maps Considering Local Soil Conditions for the State of Haryana, India

Abstract An extensive ground response analysis has been carried out in order to consider the effect of local soil conditions on surface level strong ground motions in the state of Haryana, India. Non-linear approach has been adopted to analyze 81 sites drilled up to refusal covering the entire state. It has been observed that 75 sites fall under site class D (medium dense soils), 4 sites under site class C (very dense soils), whereas only 2 sites fall under site class E (loose soils) as per the provisions of National Earthquake Hazard Reduction Program (NEHRP). For the estimation of low strain shear modulus (Gmax) using SPT N-value for different type of soils, various correlations have been used due to non-availability of in-situ measured values of shear wave velocity (Vs). The standard backbone curves for clays and sands have been used in the study in the absence of site-specific shear modulus degradation and damping ratio curves. The recorded acceleration time histories of the Ms 7.0 1991 Uttarkashi earthquake, having a focal depth of 10 km with PGA (g) ranging from 0.05g to 0.31g, have been used as input motion for the analysis. Amplification factors for peak ground acceleration (PGA) and spectral acceleration (Sa) for site class D have been calculated which are found to be comparable with those reported in NEHRP provisions. However, the site-specific hazard parameters determined for the tectonic setup of the seismic study region are quite different from that suggested by Indian standard code of practice.

Simulation of Strong Ground Motion in the National Capital Region, India, from a Future 8.5 Magnitude Earthquake Using Two-Step Empirical Green’s Function Method

ABSTRACT In this study, I simulate high-frequency ground motions at five stations in the National Capital Region (NCR) of India for a large hypothetical Mw 8.5 earthquake in the Himalayan central seismic gap, at fault-distances of about 200–300 km. A smaller magnitude earthquake (22 July 2007 Mw 4.9 Kharsali) is used as the first-step empirical Green’s function (EGF) for the synthesis of an intermediate-sized earthquake of magnitude Mw 6.8 (1991 Uttarkashi earthquake). In the second step, the records of Mw 6.8 synthetics are further used as the EGF in the simulation of the postulated Mw 8.5 earthquake. Because the target region for the postulated earthquake is devoid of the necessary information on the geophysical constraints, I perform a suite of simulations for plausible scenarios of fault dimensions, stress-drop ratios, C, and scaling factor, N (between the EGF and target earthquake). This article uses heterogeneous slip distributions and variable stress drops on the rupture plane to simulate the target earthquake, based on the power spectral density of the von Karman correlation function. The estimated values of the ground-motion intensity measure (GMIM) such as peak ground acceleration, along with the engineering parameters such as the 5% damped, pseudospectral acceleration (Sa), Arias intensity (IA), and significant duration (TD), are compared for both the recorded and the simulated time histories. The estimated GMIMs of the Mw 6.8 synthetics are examined with those of the 1991 Mw 6.8 Uttarkashi earthquake, whereas the Mw 8.5 simulations are compared with those predicted by prevalent ground-motion prediction equations for rock sites. The Mw 8.5 earthquake scenarios indicate higher GMIMs and seismic hazard in the NCR, principally due to the area being underlain by sediment layers and fluvial deposits.

Seismic Hazard of Garhwal Region, Himalaya

The region of Garhwal is one of the most seismically active areas in India. Many destructive earthquakes have occurred there in the past. The current seismic activity in Garhwal is also high. The region is characterized by a high population density; therefore, in choosing ways to develop it, protecting the population and reducing material damage from expected strong seismic events are of utmost urgency. The solution primarily requires using various antiseismic measures during construction, which are selected based on the characteristics of seismic treatments. The purpose of this research is to assess the seismic hazard and seismic treatments in some settlements of Garhwal. To solve this problem, data obtained in previous stages of studies in Western Himalaya are interpreted once again. In particular, the results of geological and geophysical and structural and geological studies have made it possible to reveal the main seismogenerating structures and determine their characteristics. The analysis of the data on strong ground motions in the epicenter areas of the Dharamsala (April 26, 1986, Mw = 5.5), Uttarkashi (October 20, 1991, Mw = 6.8), and Chamoli (March 28, 1999, Mw = 6.5) earthquakes and the study of the attenuation patterns of ground accelerations in the Garhwal region have enabled us to estimate the expected maximum magnitudes, focal depths, and source mechanisms of the earthquakes. A regional model of seismic source zones (SSZs) is proposed. Using the results of seismological and seismotectonic studies, the parameters of ground motions during the maximum credible earthquakes are estimated, such as peak ground accelerations, spectra and durations of vibrations, and the seismic-effect value in the seismic intensity scale points for some settlements in Garhwal.

Impact of Pile Head Rigidity on the Response of Piled Raft in Sand Under Pseudo-Static Loading

The 3D finite element simulations are carried out to study the impact of different pile head connection conditions, i.e., rigid and hinged connection on the response of piled rafts in sand subjected to pseudo-static horizontal loading. The time-acceleration histories of Assam (2014), Bhuj (2001), Sikkim (2011) and Uttarkashi (1991) earthquakes are considered to calculate the horizontal pseudo-static loads. Analyses results confirm that pile head connection rigidity greatly influences the behavior of piled raft in many aspects. The horizontal stiffness of piled raft is found to decrease as the rigid pile head connection changes to hinged one. Piles in a piled raft foundation is found to carry about 52–75% of the pseudo-static horizontal load for rigid connection and 32–48% for hinged connection. The horizontal deflection of pile is found maximum at the pile head and becomes negligible along the depth of pile for both cases. For rigidly connected piles, the maximum bending moment occurs at the pile head, whereas piles with hinged connection show zero bending moment at top and maximum value at a certain depth from pile head.

A Prototype Earthquake Early Warning System for Northern India

ABSTRACT Part of North-Western Himalaya particularly Uttarakhand has been identified by several eminent seismologists as gap area where large size earthquake (greater than magnitude 7) is expected. The region has witnessed two earthquakes having a magnitude greater than 6 in last 25 years (March 28, 1999 Chamoli earthquake and October 20, 1991 Uttarkashi earthquake) both having an epicenter in Gharwal region of Uttarakhand. Several studies have shown that a future large earthquake in central Himalayas can generate severe ground motion in the National capital region of Delhi, which is about 300 km from this expected source. Several densely populated cities and villages having total population of several millions are located between Delhi and Uttarakhand. These towns/cities will be severely affected by a large earthquake having an epicenter in this region. Using advancements in communication technology and real-time seismology, a project to have an earthquake early warning system for Northern India is under progress at Indian Institute of Technology, Roorkee. In this project, a dense network of 84 accelerometers has been installed covering an area of about 100 × 40 km in Garhwal region. This network has an average station to station distance of less than 10 km and all the sensors are streaming data, which is being processed in real time at central server stationed at Roorkee. This paper describes details of the network, sensors, present status of development, performance of instrumentation during recent events, and processing details.

Modeling of 2011 IndoNepal Earthquake and Scenario Earthquakes in the Kumaon Region and Comparative Attenuation Study Using PGA Distribution with the Garhwal Region

Kumaon and Garhwal regions are the chief terrains of Uttarakhand Himalaya. The present article simulates the strong ground motion of the 2011 IndoNepal earthquake in the Kumaon region using modified semi empirical technique (MSET). Acceleration records at ten stations in the near field region have been simulated which validates well with actual records and therefore confirms the reliability of MSET. In addition, MSET has been used to simulate strong motion records of future scenario earthquakes (Mw 7.0 and Mw 8.0) in Kumaon region by assuming the earthquake location same as that of 2011 IndoNepal earthquake. Isoacceleration maps are also provided, which reveals more than 400 gal value of PGA at epicentral distances less than 25 kms for an earthquake of magnitude 8.0. The comparison of isoacceleration map of future scenario earthquake (Mw 7.0) in Kumaon region has been done with isoacceleration map of 1991 Uttarkashi earthquake (Mw 6.8) in Garhwal region which suggests distinct attenuation characteristics of these two regions.

Seismic Assessment and Retrofitting of a Heritage Brick Masonry Building Using FRP

Uttarakhand in the foothills of Himalayas is considered to be one of the most tectonically active regions of northern India as it had experienced several destructive earthquakes such as Pithoragarh (1980), Uttarkashi (1991), Chamoli (1999) and Gopeshwar (2005). The state of Uttar Pradesh (now Uttarakhand) being the center of activity during British regime is having numerous historical brick masonry structures such as churches, missionaries, hospitals, administrative building and educational institutions required to be safeguarded against catastrophic future earthquakes. One such building: Forest Research Institute Dehradun which suffered extensive damages during the Uttarkashi earthquake has been considered for seismic vulnerability assessment and achieving a generalized retrofitting strategy for the region which can be extrapolated globally. Structural assessment by non-linear static analysis has been carried out for FRP retrofitted and an un-retrofitted building using FEM. Different types of FRP has been modeled numerically as wrapped around the piers of huge brick masonry structure and analyzed under site specific earthquake loading which reported in an improved performance of strengthened structure.

Testing the performance of earthquake early warning system in northern India

The main goal of present study is to test the functionality of an earthquake early warning (EEW) system (a life-saving tool), in India using synthesized data and recorded earthquake data from Taiwan. In recent time, India set up an EEW system in the central seismic gap along the Himalayan Belt, consisting of about 100 low-cost P-Alert instruments. The area, where these instruments are installed, is highly sensitive to the seismic risk with the potential of strong, major and great earthquakes. In the absence of recorded data from the Himalayas required for analysis of such system, we take advantage of recorded waveforms from Taiwan, to test the EEW system. We selected Taiwanese stations in good accordance with the Indian sensor network, to have a best fit in terms of inter station spacing. Finally, the recorded waveforms are passed through Earthworm software using tankplayer module. The system performs very well in terms of earthquake detection, P-wave picking, earthquake magnitude and location (using previously estimated regressions). Pd algorithm has been tested where the peak amplitude of vertical displacement is used for estimating magnitudes using previously regressed empirical relationship data. For the earthquakes located between Main Boundary Thrust and Main Central Thrust along with a matching instrumentation window, a good estimate of location, as well as magnitude is observed. The approach based on Pd for estimating magnitude works perfectly as compared to $$\tau_{\text{c}}$$ approach, which is more sensitive to signal-to-noise ratio. To make it more region specific, we generated synthetic seismograms from the epicenters of historical Chamoli (1999) and Uttarkashi (1991) earthquakes at EEW stations in India and checked the functionality of EEW. While placing these earthquakes within the instrumentation window, a good approximation of earthquake location and magnitude is obtained by passing these generated waveforms. The parameters used to judge the performance of EEW system included the time taken by the system in issuing warning after the confirmation of the occurrence of damaging earthquake and the lead time (time interval between the issuing of warning and arrival of damaging earthquake ground motion at a particular location). High lead times have been obtained for the plainer regions including thickly populated regions of Gangetic plains, such as Delhi National Capital Region according to the distance from the epicenter, which are the main target of EEW system.

On the paleoseismic evidence of the 1803 earthquake rupture (or lack of it) along the frontal thrust of the Kumaun Himalaya

The foothills of the Himalaya bordered by the Main Frontal Thrust (MFT) continue to be a locus of paleoseismological studies. One of such recent studies of trench stratigraphy near the central (Indian) Himalayan foothills (Malik et al., (2016) has reported multiple ruptures dated at 467–570, 1294–1587 and 1750–1932CE. The last offset has been attributed to the Uttarkashi earthquake of 1803 and the penultimate faulting, with lesser confidence to an earthquake in 1505CE. We tested these claims by logging an adjacent section on a shared scarp, and the new trench site, however, revealed a stratigraphic configuration partially in variance with from what has been reported in the earlier study. Our findings do not support the previous interpretation of the trench stratigraphy that suggested multiple displacements cutting across a varied set of deformed stratigraphic units leading up to the 1803 rupture. The current interpretation posits a single episode of a low-angle displacement at this site occurred between 1266 CE and 1636. Our results suggest a single medieval earthquake, conforming to what was reported from the previously studied neighboring sites to the east and west. The present study while reiterating a great medieval earthquake questions the assumption that the 1803 earthquake ruptured the MFT. Although a décollement earthquake, the 1803 rupture may have been arrested midway on the basal flat, and fell short of reaching the MFT, somewhat comparable to a suite of blind thrust earthquakes like the1905 Kangra and the 1833 Nepal earthquakes.

IMPACT ON STRUCTURAL BEHAVIOR DUE TO INSTALLATION OF BILLBOARD

Installation of billboards on various structures adjacent to busy roads has become common practice as they provide high economic to the local municipal corporation or private business organisations. Till recent, design of billboards and its installation on a structure was of less importance, but recent large wind cyclones had led to the collapse of billboards and structural cracks. This incident has raised doubts in structural engineering community for the resistance of buildings with billboards during earthquakes. In this study, an existing building with the recent installation of a billboard has considered, and dynamic analysis is carried out for three different ground motions viz. El Centro earthquake, Loma Prieta earthquake and Uttarkashi earthquake for understanding the change in its behaviour with and without billboard. The structure has shown an increment of response due to the installation of a billboard during earthquakes.

Empirical Attenuation relationship for Peak Ground Horizontal Acceleration for North-East Himalaya

Empirical Attenuation relationship for Peak Ground Horizontal Acceleration for North-East Himalaya

Liquefaction and Earthquake Response Analysis of Panipat Pond Ash Embankment in India

In this study, liquefaction and earthquake response analysis of Panipat pond ash embankment in India has been carried out considering saturated and natural water table conditions. Laboratory and field studies have been carried out to obtain the material properties required for the nonlinear response analysis of the Panipat pond ash embankment. Nonlinear finite element analysis has been carried out by using open system for earthquake engineering simulation (OpenSees). Three earthquakes namely Chamba, Chamoli and Uttarkashi earthquakes have been considered for liquefaction and earthquake response analysis. The standard penetration test (SPT)-[Formula: see text] value indicates that the ash deposit in Panipat pond ash embankment is in loose to medium dense state. The excess pore pressure ratio obtained from the analysis is found to be one or more than one below upstream and downstream locations of the pond ash embankment for both saturated and natural water table conditions. The horizontal and vertical displacement is found to be maximum near the toe and first rise slope of pond ash embankment. Hence, ash embankment in Panipat is prone to liquefaction under the excitation of moderate to high earthquake loading.

Seismic Analysis of Delhi Metro Underground Tunnels

Metro underground tunnels are strategic elements in transportation and utility networks in any metropolitan city and their importance makes their vulnerability to earthquakes a very sensitive issue. A large earthquake would not only cause loss of human lives but can also damage lot of other pertinent infrastructure. In order to reduce the potential loss of serviceability, it is essential to reduce the possible risk associated and the effects of damage. Underground structures cannot be treated as completely exempt to the effects of ground shaking, as demonstrated by the recent Kobe earthquake of 1995, Chi–Chi earthquake of 1999, and Niigata earthquake of 2004, where several underground structures suffered severe damage. Earlier work in this area suggests that various authors have presented explicit expressions for axial force, shear force and bending moment developed in the RC liners of tunnels. Some numerical studies were also undertaken. In this paper, an attempt has been made to simulate the case of Delhi metro underground tunnels through PLAXIS 2D and study their response to 1991 Uttarkashi earthquake of lower Himalaya and then conduct some parametric study. The response so obtained has been compared with the available closed form solutions. Damping plays a significant role in seismic analysis. Analysis shows that forces in RC liners reduce with increase in damping. Similarly, displacements, both in soil and RC liners, decrease with increase in damping. Amplification in horizontal acceleration occurs due to reduction in damping ratio. The effect of horizontal component of 1991 Uttarkashi earthquake was found to be more critical than the vertical component, though of course the influence of vertical component was also found to be significant. It has therefore been realized that seismic response of metro underground tunnels to the both horizontal as well as vertical component of earthquake should be considered in design.

Simulation of near-field ground motion characteristics of May 01, 2013, Doda earthquake using modified semi-empirical approach

Strong ground motions are the most desirable for the earthquake-resistant design of structures. If the site at which a major construction is required has less ground motion records, then artificial ground motions will serve the purpose. In highly seismic areas like Kashmir and the Himalaya region, artificial ground motions are quite helpful. Artificial accelerograms can be generated either through analytical or numerical procedures. Several methods were suggested in the literature for generating artificial ground motions. However, suitability of method for the region is to be understood before application. The main objective of this paper is to generate synthetic accelerograms of May 01, 2013, Doda earthquake using modified semi-empirical approach. A MATLAB code is written to generate the ground motion records of 1991 Uttarkashi earthquake and also validate the results. Based on effectiveness of the code, the ground motion records of 2013 Doda earthquake is generated at three near-field seismic stations. The study reveals that the semi-empirical approach has effectively generated the ground motions at many stations. Simulated ground motions of the 2013 Doda earthquake are satisfactorily good at Chamba, Jammu and Palampur stations along FN and FP components. Also, the acceleration response spectra are fairly good at periods longer than 2.0 s.

Spectral Characterization of Himalayan Near-Fault Ground Motion

Near-Fault Ground Motion (NFGM) spectral characteristics of three moderate-sized Himalayan earthquakes, viz., the 1986 Dharamsala earthquake (Mw = 5:5), the 1991 Uttarkashi earthquake (Mw = 6:8), and the 1999 Chamoli earthquake (Mw = 6:5) have been studied from the 33 available strong ground motion recordings. Pulse characteristics of fault-normal components in terms of pulse-periods and pulse-indicators have been extracted adopting wavelet analysis. Seven mother wavelets were used in the analysis, and it was found that db4 and db7 mother wavelets were more efficient in extracting the pulse-type characteristics. NFGM spectra, at Bhatwari and Gopeshwar stations, showed higher spectral amplitudes in the velocity-sensitive and acceleration-sensitive regions compared to Indian codal response spectra. This is attributed to high PGV/PGA ratios. The study shows that NFGM leads to widening of acceleration-sensitive region, and the structures that are designed according to the Indian seismic code as flexible structures shall behave as stiff structures when subjected to NFGM.

Incorporating Simulated Ground Motion in Seismic Risk Assessment: Application to the Lower Indian Himalayas

In this study, the effects of implementing stochastic finite fault ground motion simulations in earthquake hazard and risk assessment are evaluated. The investigations are conducted for the city of Dehradun (Indian Himalayas). We compare two ground motion estimation techniques: a ground motion prediction equation–based technique and a simulation-based technique. The comparison focuses on the differences the techniques imply on earthquake damage and loss estimates. Ground motion simulations are first calibrated against the instrumental recordings of the 1991 Mw 6.8 Uttarkashi earthquake. Afterward, a number of events are considered with different magnitude, distance, and azimuth to the source. Results indicate large differences between ground motion and loss estimates derived by the two methods, especially in the direction of rupture propagation, which persist to 2–2.5 fault lengths distance. It is therefore strongly recommended to consider rupture kinematics and orientation to the test bed when providing ground motion estimates for near-field earthquake loss assessment studies.

Earthquake ground motion predictive equations for Garhwal Himalaya, India

Predictive equations based on the stochastic approach are developed for earthquake ground motions from Garhwal Himalayan earthquakes of 3.5≤Mw≤6.8 at a distance of 10≤R≤250km. The predicted ground motion parameters are response spectral values at frequencies from 0.25 to 20Hz, and peak ground acceleration (PGA). The ground motion prediction equations (GMPEs) are derived from an empirically based stochastic ground motion model. The GMPEs show a fair agreement with the empirically developed ground motion equations from Himalaya as well as the NGA equation. The proposed relations also reasonably predict the observed ground motion of two major Himalayan earthquakes from Garhwal Himalayan region. For high magnitudes, there is insufficient data to satisfactorily judge the relationship; however it reasonably predicts the 1991 Uttarkashi earthquake (Mw=6.8) and 1999 Chamoli earthquake (Mw=6.4) from Garhwal Himalaya region.

Modeling of strong motion generation area of the Uttarkashi earthquake using modified semiempirical approach

The semiempirical approach based on envelope summation method given by Midorikawa (Tectonophysics 218:287–295, 1993) has been modified in this paper for modeling of strong motion generation areas (SMGAs). Horizontal components of strong ground motion have been simulated using modifications in the semiempirical approach given by Joshi et al. (Nat Hazard 71:587–609, 2014). Various modifications in the technique account for finite rupture source, layering of earth, componentwise division of energy and frequency-dependent radiation pattern. In this paper, SMGAs of the Uttarkashi earthquake have been modeled. Two different isolated wave packets in the recorded accelerogram have been identified from recorded ground motion, which accounts for two different SMGAs in the entire rupture plane. The approximate locations of SMGAs within the rupture plane were estimated using spatio-temporal variation of 77 aftershocks. Source parameters of each SMGA were calculated from theoretical and observed source displacement spectra computed from two different wave packets in the record. The final model of rupture plane responsible for the Uttarkashi earthquake consists of two SMGAs, and the same has been used to simulate horizontal components of acceleration records at different station using modified semiempirical technique. Comparison of the observed and simulated acceleration records in terms of root mean square error confirms the suitability of the final source model for the Uttarkashi earthquake.