scholarly journals Estimation of crustal deformation parameters and strain build-up in Northwest Himalaya using GNSS data measurements

2021 ◽  
Vol 51 (3) ◽  
pp. 225-243
Author(s):  
Abhishek YADAV ◽  
Suresh KANNAUJIYA ◽  
Prashant Kumar CHAMPATI RAY ◽  
Rajeev Kumar YADAV ◽  
Param Kirti GAUTAM
Keyword(s):  
Seismic Hazard ◽  
Strain Rate ◽  
Accumulation Rate ◽  
Himalayan Region ◽  
Compression Rate ◽  
Strain Accumulation ◽  
Gps Measurements ◽  
Baseline Method ◽  
Maximum Shear Strain ◽  
Continuous Gps

GPS measurements have proved extremely useful in quantifying strain accumulation rate and assessing seismic hazard in a region. Continuous GPS measurements provide estimates of secular motion used to understand the earthquake and other geodynamic processes. GNSS stations extending from the South of India to the Higher Himalayan region have been used to quantify the strain build-up rate in Central India and the Himalayan region to assess the seismic hazard potential in this realm. Velocity solution has been determined after the application of Markov noise estimated from GPS time series data. The recorded GPS data are processed along with the closest International GNSS stations data for estimation of daily basis precise positioning. The baseline method has been used for the estimation of the linear strain rate between the two stations. Whereas the principal strain axes, maximum shear strain, rotation rate, and crustal shortening rate has been calculated through the site velocity using an independent approach; least-square inversion approach-based triangulation method. The strain rate analysis estimated by the triangulation approach exhibits a mean value of extension rate of 26.08 nano-strain/yr towards N131°, the compression rate of –25.38 nano-strain/yr towards N41°, maximum shear strain rate of 51.47 nano-strain/yr, dilation of –37.57 nano-strain/yr and rotation rate of 0.7°/Ma towards anti-clockwise. The computed strain rate from the Baseline method and the Triangulation method reports an extensive compression rate that gradually increases from the Indo-Gangetic Plain in South to Higher Himalaya in North. The slip deficit rate between India and Eurasia Plate in Kumaun Garhwal Himalaya has been computed as 18±1.5 mm/yr based on elastic dislocation theory. Thus, in this study, present-day surface deformation rate and interseismic strain accumulation rate in the Himalayan region and the Central Indian region have been estimated for seismic hazard analysis using continuous GPS measurements.

Surface strain accumulation and the seismic moment tensor

1997 ◽  
Vol 87 (5) ◽  
pp. 1345-1353
Author(s):  
J. C. Savage ◽  
R. W. Simpson
Keyword(s):  
Strain Rate ◽  
Accumulation Rate ◽  
Moment Tensor ◽  
Surface Strain ◽  
Seismogenic Zone ◽  
Strain Accumulation ◽  
Average Strain ◽  
Average Strain Rate ◽  
Double Couple ◽  
Scalar Moment

Abstract Although the scalar moment accumulation rate within the seismogenic zone beneath a given area is sometimes deduced from the observed average surface strain accumulation rate over that same area (e.g., Working Group on California Earthquake Probabilities, 1995), the correspondence between the two is very uncertain. The equivalence between surface strain accumulation and scalar moment accumulation is based on Kostrov's (1974) relation between the average strain rate over a volume and the moment-rate tensor for that volume. The average strain rate over the volume is replaced by the average strain rate measured at the free surface to deduce an approximate moment-rate tensor. Only in exceptional circumstances will that moment-rate tensor correspond to a double-couple mechanism, a mechanism that can be represented by a scalar moment accumulation rate. More generally, the moment tensor must be resolved into the superposition of two or more double-couple mechanisms, and that resolution can be done in many ways, each with its own scalar moment rate. Thus the resolution is not unique. This is demonstrated by deducing scalar moment accumulation rates for a GPS network that covers most of California south of San Francisco. It is shown that resolutions into different double-couple mechanisms lead to scalar moment accumulation rates differing by factors of ∼2. We suggest that the minimum scalar moment rate equivalent to principal surface strain rates ɛ1 and ɛ2 acting over the area A is M0(min) = 2μHA Max (¦ɛ1¦, ¦ɛ2¦, ¦ɛ1 + ɛ2¦), where μ is the rigidity and H the depth of seismogenic zone, and the function Max is equal to the largest of its arguments. Within the uncertainites of measurement, the scalar moment accumulation rate in southern California based on that approximation is in balance with the average historic seismic moment release rate so that no current earthquake deficit need be accumulating.

scholarly journals Why Do Great Earthquakes Follow Each Other at Subduction Zones?

Eos ◽  
2017 ◽  
Author(s):  
Terri Cook
Keyword(s):  
South America ◽  
Subduction Zones ◽  
Great Earthquake ◽  
Strain Accumulation ◽  
Gps Measurements ◽  
Great Earthquakes ◽  
Enhanced Strain ◽  
Continuous Gps

A decade of continuous GPS measurements in South America indicates that enhanced strain accumulation following a great earthquake can initiate failure along adjacent fault segments.

scholarly journals GPS Velocity and Strain Rate Fields in Southwest Anatolia from Repeated GPS Measurements

Sensors ◽  
2009 ◽  
Vol 9 (3) ◽  
pp. 2017-2034 ◽  
Author(s):  
Saffet Erdoğan ◽  
Muhammed Şahin ◽  
İbrahim Tiryakioğlu ◽  
Engin Gülal ◽  
Ali Kazım Telli
Keyword(s):  
Strain Rate ◽  
Gps Measurements

Strain accumulation in Owens Valley, California, 1974 to 1988

1995 ◽  
Vol 85 (1) ◽  
pp. 151-158
Author(s):  
J. C. Savage ◽  
M. Lisowski
Keyword(s):  
Strain Rate ◽  
Coordinate System ◽  
Strain Accumulation ◽  
Lateral Deformation ◽  
Lateral Shear ◽  
Owens Valley ◽  
Conventional Model ◽  
Measured Strain ◽  
Standard Deviations ◽  
Buried Fault

Abstract Strain accumulation observed over the 1974 to 1988 interval in a 25 by 100 km aperture trilateration network spanning Owens Valley is adequately described by a strain rate that is uniform in space and time. The tensor strain-rate components referred to a coordinate system with the 2 axis directed N18°W (parallel to the trend of the valley) and the 1 axis N72°E are ∈˙11′ = 0.042 ± 0.014 μstrain/yr, ∈˙12′ = -0.058 ± 0.007 μstrain/yr, and ∈˙22′ = 0.002 ± 0.014 μstrain/yr; quoted uncertainties are standard deviations and extension is reckoned positive. Across the 25-km breadth of the network, this amounts to 1.0 ± 0.3 mm/yr extension normal to the axis of the valley, 2.9 ± 0.4 mm/yr right-lateral shear across the axis, and no extension parallel to the axis. If the measured strain accumulation is attributed to slip on the deeper section of the Owens Valley fault with the uppermost 10 km of the fault locked, the observed right-lateral deformation would imply about 7 mm/yr right-lateral slip on the buried fault, much greater than the geologic estimate of 2 ± 0.5 mm/yr right-lateral secular slip (Beanland and Clark, 1994). Nor is the observed uplift profile across the valley consistent with continuing normal slip on just the deep segment of the Owens Valley fault; normal slip at depth on the Sierra frontal fault also seems to be required. The observed deformation across Owens Valley apparently implies processes more complicated than those represented by the conventional model of strain accumulation along a throughgoing fault.

scholarly journals Investigation of correlation of the variations in land subsidence (detected by continuous GPS measurements) and methodological data in the surrounding areas of Lake Urmia

2012 ◽  
Vol 19 (6) ◽  
pp. 675-683 ◽  
Author(s):  
K. Moghtased-Azar ◽  
A. Mirzaei ◽  
H. R. Nankali ◽  
F. Tavakoli
Keyword(s):  
Time Series ◽  
Land Subsidence ◽  
Salt Lake ◽  
Linear Trend ◽  
Groundwater Resources ◽  
Time Interval ◽  
Gps Measurements ◽  
Lake Urmia ◽  
North West ◽  
Continuous Gps

Abstract. Lake Urmia, a salt lake in the north-west of Iran, plays a valuable role in the environment, wildlife and economy of Iran and the region, but now faces great challenges for survival. The Lake is in immediate and great danger and is rapidly going to become barren desert. As a result, the increasing demands upon groundwater resources due to expanding metropolitan and agricultural areas are a serious challenge in the surrounding regions of Lake Urmia. The continuous GPS measurements around the lake illustrate significant subsidence rate between 2005 and 2009. The objective of this study was to detect and specify the non-linear correlation of land subsidence and temperature activities in the region from 2005 to 2009. For this purpose, the cross wavelet transform (XWT) was carried out between the two types of time series, namely vertical components of GPS measurements and daily temperature time series. The significant common patterns are illustrated in the high period bands from 180–218 days band (~6–7 months) from September 2007 to February 2009. Consequently, the satellite altimetry data confirmed that the maximum rate of linear trend of water variation in the lake from 2005 to 2009, is associated with time interval from September 2007 to February 2009. This event was detected by XWT as a critical interval to be holding the strong correlation between the land subsidence phenomena and surface temperature. Eventually the analysis can be used for modeling and prediction purposes and probably stave off the damage from subsidence phenomena.

Induced Seismicity in Western Canada Linked to Tectonic Strain Rate: Implications for Regional Seismic Hazard

2018 ◽  
Vol 45 (20) ◽  
Author(s):  
Honn Kao ◽  
Roy Hyndman ◽  
Yan Jiang ◽  
Ryan Visser ◽  
Brindley Smith ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Strain Rate ◽  
Induced Seismicity ◽  
Western Canada

scholarly journals Dynamics and Structure of Griesgletscher, Switzerland

1980 ◽  
Vol 25 (92) ◽  
pp. 215-228 ◽  
Author(s):  
M. J. Hambrey ◽  
A. G. Milnes ◽  
H. Siegenthaler
Keyword(s):  
Strain Rate ◽  
Flow Line ◽  
Compressive Strain ◽  
Local Deformation ◽  
Strain History ◽  
Strain Rates ◽  
Shear Strain Rate ◽  
Maximum Shear Strain ◽  
Alpine Valley ◽  
Ablation Area

AbstractA detailed investigation has been carried out on the dynamics of an Alpine valley glacier of relatively simple shape and the results are considered in relation to the development of secondary structures. Ice velocity reaches a maximum near the top of a small ice fall (40 m a−1) which also coincides approximately with the equilibrium line. Flow lines converge in the accumulation area but are roughly parallel in the ablation area. The “regional” strain-rate pattern is rather complex. Approximate longitudinal extension is evident in the accumulation area and strain-rates reach high values at the south margin and in the ice fall (up to 0.12 a−1). In the ablation area, strain-rates are comparatively small and in general indicate longitudinal compression. “Local” deformation rates obtained in the area beneath the ice fall and along a flow line near one of the margins reveal complex patterns of deformation within small areas.There is no clear relationship between foliation and strain-rates (and by analogy stresses), except in the case of longitudinal foliation in marginal areas which, if actively developing, lies approximately parallel to a direction of maximum shear strain-rate. It is more important to consider the relationship of this structure to strain history. Results from this study indicate that, regardless of the initial orientation of the foliation in relation to the strain ellipse, it attains approximate parallelism with the long axis of the ellipse as deformation progresses.It is also shown that many foliations originate from pre-existing layered structures such as stratification or crevasse traces. This problem is discussed particularly with reference to an arcuate foliation which originates in the ice fall and is believed to represent tensional veins, subsequently subjected to compressive strain within and below the ice fall.

scholarly journals The theory of plane plastic strain for anisotropic metals

1949 ◽  
Vol 198 (1054) ◽  
pp. 428-437 ◽  
Keyword(s):  
Plastic Strain ◽  
Strain Rate ◽  
Shear Strain ◽  
Plane Strain ◽  
Yield Criterion ◽  
Elliptic Functions ◽  
Shear Strain Rate ◽  
Maximum Shear Strain ◽  
Geometrical Properties ◽  
Plane Plastic

A yield criterion and plastic stress-strain relations are formulated for anisotropic metals deformed under conditions of plane strain. The equations are shown to be hyperbolic, the characteristics coinciding with the directions of maximum shear strain-rate. When the anisotropy is uniformly distributed, the variation of the stresses along the characteristics is expressed in terms of elliptic functions, and geometrical properties of the field of characteristics are established. The theory is applied to the problem of indentation by a flat die.

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