<p>Landslides begin with the detachment of a mass and end with its impact a... more <p>Landslides begin with the detachment of a mass and end with its impact at lower altitude. To simultaneously model seismic signals produced by these processes, we consider a double single-force model. We applied this source model to the seismic signals generated by the landslide in Uttarakhand, India, on February 7th, 2021. We model the seismic recordings at 12 seismic stations located at less than 100 km epicentral distance. We perform the source inversion by fitting low-frequency (0.08-0.15 Hz) three component (vertical, radial, transversal) waveforms in the time and simultaneously their amplitude spectra in the frequency domain. We compare our results with those obtained for a single-force model applied to each pulse separately. Our results identify two energetic pulses separated by a time delay of ~1 minute. The amplitude of the second pulse, interpreted as the impact, is ~3 times larger than the first one, and of opposite sign. Together with visual observations of the landslide itself, our results confirm that the first pulse was produced by the detachment of the rock mass and the second one by the impact of the mass in the valley. The orientations of the single forces are consistent with the slope geometry and the direction of the debris flow. We discuss statistical measures of fit of the two different inversion approaches and the possible strengths and weaknesses of the new double single-force model.</p>
the Mandollagudem teCHVIL Cluster located in nalgonda District, telangana falls under drought pro... more the Mandollagudem teCHVIL Cluster located in nalgonda District, telangana falls under drought prone area as it receives an average rainfall of 620 mm. the region is characterised by low infiltration of surface water and poor connectivity between the aquifers. Groundwater levels dropped significantly during the past decade due to the over exploitation of ground water induced by the shifting of crop pattern from Castor/ Cotton to paddy cultivation in addition to the exogenous processes. since it is very difficult to suddenly shift to new crop, we suggest that the adoption of the system of Rice Intensification (sRI) method along with Alternate Wetting and Drying (AWD) and Direct seeding (Ds) methods will reduce the consumption of water up to 30 percent with more grain productivity compared to continuous uncontrolled flooded field methods. From the statistical analysis of various data sets, it is concluded that the adoption of low water consuming crops and scientific irrigation practice...
Singular Spectrum Analysis (SSA) is a popular time series analysis tool. Numerous studies have pr... more Singular Spectrum Analysis (SSA) is a popular time series analysis tool. Numerous studies have proven its efficacy in processing the data contaminated with various kinds of noises. As the geophysical field observations are highly non-linear and contains random as well as coherent noises, the analysis of data using SSA provides the significant information in terms of Eigen properties of the system under investigation. Unlike standard Fourier and wavelet methods, the basis functions of the SSA are completely data adaptive (Eigenvectors of trajectory matrix). Such data adaptive basis functions enable the self similarity of time series in data gap filling and noise suppression. Here we made an effort to briefly discuss the principal component analysis,frequency filtering, noise suppression and data gap filling of SSA and their application in time domain geophysical data processing.
<p>Debris flows and corresponding floods are a significant ... more <p>Debris flows and corresponding floods are a significant natural hazard for downstream communities in vulnerable regions, as yet unpredictable triggers and remote source locations might cause dynamics which are difficult to measure and quantify. Continuous observational coverage offered by seismic monitoring is one potential avenue for addressing this problem. Displacement of mass at Earth’s surface generates elastic seismic waves, which carry information about the temporal and spatial variability of the source and which can be recorded by seismometers at high temporal resolution across large spatial scales. Here, we report on seismic observations of the destructive 2021 Uttarakhand (India) debris flow and flood events. By means of a dense regional seismic network, we track and quantify the spatial and temporal evolution of the flood. Using continuous time-stamped seismic observations, a coherent signal of the flood movement is observed in a limited frequency band which can be tracked down the valley during the flood duration. Our analysis highlights potential benefits of using a network-wide seismic monitoring systems.</p>
<p>The 7 February Chamoli, Uttarakhand singularity imposed ... more <p>The 7 February Chamoli, Uttarakhand singularity imposed a severe geomorphic crisis. While remote sensing imagery quickly identified a major rock avalanche as its origin, there is a fundamental lack in high precision temporal information on the kinetics of this event about when, how, and why it evolved from a slope failure into a channel-confined mass wasting process, and ultimately into a debris laden flood. Furthermore, while the initial rock slide could be detected and located by global seismic networks, it was the flood which caused most of the destruction and fatalities. Yet, that part of the process cascade remained elusive in global seismic data sets.</p><p>Here, we present a detailed anatomy of the hazard cascade, with emphasis on the flood part. Using information from a dense seismic network, we explore the limits of detection and constrain its propagation velocity. By jointly inverting two physical models that predict spectral signal properties of floods, we estimate important hydraulic and sediment transport metrics. These information are key for designing any future early warning infrastructure.</p>
<p>Landslides begin with the detachment of a mass and end with its impact a... more <p>Landslides begin with the detachment of a mass and end with its impact at lower altitude. To simultaneously model seismic signals produced by these processes, we consider a double single-force model. We applied this source model to the seismic signals generated by the landslide in Uttarakhand, India, on February 7th, 2021. We model the seismic recordings at 12 seismic stations located at less than 100 km epicentral distance. We perform the source inversion by fitting low-frequency (0.08-0.15 Hz) three component (vertical, radial, transversal) waveforms in the time and simultaneously their amplitude spectra in the frequency domain. We compare our results with those obtained for a single-force model applied to each pulse separately. Our results identify two energetic pulses separated by a time delay of ~1 minute. The amplitude of the second pulse, interpreted as the impact, is ~3 times larger than the first one, and of opposite sign. Together with visual observations of the landslide itself, our results confirm that the first pulse was produced by the detachment of the rock mass and the second one by the impact of the mass in the valley. The orientations of the single forces are consistent with the slope geometry and the direction of the debris flow. We discuss statistical measures of fit of the two different inversion approaches and the possible strengths and weaknesses of the new double single-force model.</p>
the Mandollagudem teCHVIL Cluster located in nalgonda District, telangana falls under drought pro... more the Mandollagudem teCHVIL Cluster located in nalgonda District, telangana falls under drought prone area as it receives an average rainfall of 620 mm. the region is characterised by low infiltration of surface water and poor connectivity between the aquifers. Groundwater levels dropped significantly during the past decade due to the over exploitation of ground water induced by the shifting of crop pattern from Castor/ Cotton to paddy cultivation in addition to the exogenous processes. since it is very difficult to suddenly shift to new crop, we suggest that the adoption of the system of Rice Intensification (sRI) method along with Alternate Wetting and Drying (AWD) and Direct seeding (Ds) methods will reduce the consumption of water up to 30 percent with more grain productivity compared to continuous uncontrolled flooded field methods. From the statistical analysis of various data sets, it is concluded that the adoption of low water consuming crops and scientific irrigation practice...
Singular Spectrum Analysis (SSA) is a popular time series analysis tool. Numerous studies have pr... more Singular Spectrum Analysis (SSA) is a popular time series analysis tool. Numerous studies have proven its efficacy in processing the data contaminated with various kinds of noises. As the geophysical field observations are highly non-linear and contains random as well as coherent noises, the analysis of data using SSA provides the significant information in terms of Eigen properties of the system under investigation. Unlike standard Fourier and wavelet methods, the basis functions of the SSA are completely data adaptive (Eigenvectors of trajectory matrix). Such data adaptive basis functions enable the self similarity of time series in data gap filling and noise suppression. Here we made an effort to briefly discuss the principal component analysis,frequency filtering, noise suppression and data gap filling of SSA and their application in time domain geophysical data processing.
<p>Debris flows and corresponding floods are a significant ... more <p>Debris flows and corresponding floods are a significant natural hazard for downstream communities in vulnerable regions, as yet unpredictable triggers and remote source locations might cause dynamics which are difficult to measure and quantify. Continuous observational coverage offered by seismic monitoring is one potential avenue for addressing this problem. Displacement of mass at Earth’s surface generates elastic seismic waves, which carry information about the temporal and spatial variability of the source and which can be recorded by seismometers at high temporal resolution across large spatial scales. Here, we report on seismic observations of the destructive 2021 Uttarakhand (India) debris flow and flood events. By means of a dense regional seismic network, we track and quantify the spatial and temporal evolution of the flood. Using continuous time-stamped seismic observations, a coherent signal of the flood movement is observed in a limited frequency band which can be tracked down the valley during the flood duration. Our analysis highlights potential benefits of using a network-wide seismic monitoring systems.</p>
<p>The 7 February Chamoli, Uttarakhand singularity imposed ... more <p>The 7 February Chamoli, Uttarakhand singularity imposed a severe geomorphic crisis. While remote sensing imagery quickly identified a major rock avalanche as its origin, there is a fundamental lack in high precision temporal information on the kinetics of this event about when, how, and why it evolved from a slope failure into a channel-confined mass wasting process, and ultimately into a debris laden flood. Furthermore, while the initial rock slide could be detected and located by global seismic networks, it was the flood which caused most of the destruction and fatalities. Yet, that part of the process cascade remained elusive in global seismic data sets.</p><p>Here, we present a detailed anatomy of the hazard cascade, with emphasis on the flood part. Using information from a dense seismic network, we explore the limits of detection and constrain its propagation velocity. By jointly inverting two physical models that predict spectral signal properties of floods, we estimate important hydraulic and sediment transport metrics. These information are key for designing any future early warning infrastructure.</p>
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Papers by Rajesh Rekapalli