Rupture process of the<i>M<sub>w</sub></i> = 7.9 2015 Gorkha earthquake (Nepal): Insights into Himalayan megathrust segmentation

Grandin, R.; Vallée, Martin; Satriano, Claudio; Lacassin, Robin; Klinger, Yann; Simões, Martine; Bollinger, Laurent

doi:10.1002/2015gl066044

Cited by 194 publications

(173 citation statements)

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“…In addition to this, some cases of liquefaction and sand blows in southern and north-western fringes of Kathmandu Valley were particularly observed. Due to directivity effects, Gorkha seismic sequence was confined towards the east of the epicentre (Grandin et al 2015) and shaking was not intense in the southern plains of Nepal. Thus only one liquefaction surface manifestation was reported in Chitwan district in case of plains.…”

Section: Liquefactionmentioning

confidence: 99%

Unearthed lessons of 25 April 2015 Gorkha earthquake (M_W 7.8): geotechnical earthquake engineering perspectives

Gautam¹

2017

Geomatics, Natural Hazards and Risk

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Gorkha earthquake (M W 7.8) of 25 April 2015 struck central, eastern and western Nepal and neighbouring areas. Enormous losses during Gorkha earthquake were attributed to collapse of 498,852 buildings, 446 public health facilities and partial damage of 256,697 buildings, 765 health facilities as well as severely affected 2900 cultural and historical sites. Anomalies were in particular observed in terms of localized damage and recurrent damages during 1833, 1934, 1988 and 2015 earthquakes. This paper reports geotechnical earthquake engineering observations noted during field reconnaissance conducted in affected areas. Damage reports from historical as well as recent Gorkha earthquakes are mapped in this paper. To depict lessons, forensic interpretations are presented considering 1833, 1934, 1988 and 2015 earthquakes.

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Section: Liquefactionmentioning

confidence: 99%

Unearthed lessons of 25 April 2015 Gorkha earthquake (M_W 7.8): geotechnical earthquake engineering perspectives

Gautam¹

2017

Geomatics, Natural Hazards and Risk

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“…9). The locking line has been found to coincide with the deeper crustal ramp on the MHT and the seismic-to-aseismic transition is a function of the thermorheological property of this detachment surface (Ader et al 2012;Grandin et al 2015). It is therefore understandable that the Gorkha main-shock initiated close to the downdip edge of the locked zone, underneath the Higher Himalaya and ruptured updip.…”

Section: Discussionmentioning

confidence: 97%

“…Waveform data is filtered between 0.2 and 5 Hz, to utilize a broad band of frequencies for the study of rupture time history of the earthquakes. The low-and high-frequency corners at 0.2 and 5 Hz, respectively, provide a broader band than all previous studies Grandin et al 2015;Yagi & Okuwaki 2015) and contain information necessary to understand the detailed spatiotemporal variation of the rupture process. The steps of our analysis are briefly outlined below.…”

Section: B a C K -P Ro J E C T I O N U S I N G M U Lt I P L E T E L Ementioning

confidence: 99%

“…However, significant variations in the details of the rupture process, ranging from linearly distributed high-frequency sources with constant rupture velocity Meng et al 2016), to multistage rupture , and depth dependent variation in rupture velocity ) have been reported. Joint inversion of teleseismic waves, strong ground motion data, high-rate and static GPS data and SAR imagery (Galetzka et al 2015;Grandin et al 2015) pointed to a simple unilateral rupture with steady rupture velocity. The downdip limit of the rupture has been conjectured to coincide with the junction between the frontal flat and deeper steeply dipping ramp on the MHT.…”

Section: Introductionmentioning

confidence: 99%

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The 2015 April 25 Gorkha (Nepal) earthquake and its aftershocks: implications for lateral heterogeneity on the Main Himalayan Thrust

Kumar¹,

Singh²,

Mitra³

et al. 2016

Geophys. J. Int.

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S U M M A R YThe 2015 Gorkha earthquake (M w 7.8) occurred by thrust faulting on a ∼150 km long and ∼70 km wide, locked downdip segment of the Main Himalayan Thrust (MHT), causing the Himalaya to slip SSW over the Indian Plate, and was followed by major-to-moderate aftershocks. Back projection of teleseismic P-wave and inversion of teleseismic body waves provide constraints on the geometry and kinematics of the main-shock rupture and source mechanism of aftershocks. The main-shock initiated ∼80 km west of Katmandu, close to the locking line on the MHT and propagated eastwards along ∼117 • azimuth for a duration of ∼70 s, with varying rupture velocity on a heterogeneous fault surface. The main-shock has been modelled using four subevents, propagating from west-to-east. The first subevent (0-20 s) ruptured at a velocity of ∼3.5 km s −1 on a ∼6 • N dipping flat segment of the MHT with thrust motion. The second subevent (20-35 s) ruptured a ∼18 • W dipping lateral ramp on the MHT in oblique thrust motion. The rupture velocity dropped from 3.5 km s −1 to 2.5 km s −1 , as a result of updip propagation of the rupture. The third subevent (35-50 s) ruptured a ∼7 • N dipping, eastward flat segment of the MHT with thrust motion and resulted in the largest amplitude arrivals at teleseismic distances. The fourth subevent (50-70 s) occurred by left-lateral strikeslip motion on a steeply dipping transverse fault, at high angle to the MHT and arrested the eastward propagation of the main-shock rupture. Eastward stress build-up following the mainshock resulted in the largest aftershock (M w 7.3), which occurred on the MHT, immediately east of the main-shock rupture. Source mechanisms of moderate aftershocks reveal stress adjustment at the edges of the main-shock fault, flexural faulting on top of the downgoing Indian Plate and extensional faulting in the hanging wall of the MHT.

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“…Sentinel-1A data have since been used to make observations of deformation that is centimetres-to-metres in magnitude, associated with earthquakes (e.g., Mw 7.8 Gorkha, Nepal: [19][20][21][22]); volcanic eruptions (e.g., Fogo, Cape Verde: [23]); and the development of sink holes (e.g., Wink, Texas: [24]). However, the detection of small-magnitude displacements, such as subsidence of the Perth Basin, is reliant on longer time series of images.…”

Section: Introductionmentioning

confidence: 99%

First Results from Sentinel-1A InSAR over Australia: Application to the Perth Basin

2017

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Past ground-based geodetic measurements in the Perth Basin, Australia, record small-magnitude subsidence (up to 7 mm/y), but are limited to discrete points or traverses across parts of the metropolitan area. Here, we investigate deformation over a much larger region by performing the first application of Sentinel-1A InSAR data to Australia. The duration of the study is short (0.7 y), as dictated by the availability of Sentinel-1A data. Despite this limited observation period, verification of Sentinel-1A with continuous GPS and independent TerraSAR-X provides new insights into the deformation field of the Perth Basin. The displacements recorded by each satellite are in agreement, identifying broad (>5 km wide) areas of subsidence at rates up to 15 mm/y. Subsidence at rates greater than 20 mm/y over smaller regions (∼2 km wide) is coincident with wetland areas, where displacements are temporally correlated with changes in groundwater levels in the unconfined aquifer. Longer InSAR time series are required to determine whether these measured displacements are representative of long-term deformation or (more likely) seasonal variations. However, the agreement between datasets demonstrates the ability of Sentinel-1A to detect small-magnitude deformation over different spatial scales (from 2 km-10 s of km) in the Perth Basin. We suggest that, even over short time periods, these data are useful as a reconnaissance tool to identify regions for subsequent targeted studies, particularly given the large swath size of radar acquisitions, which facilitates analysis of a broader portion of the deformation field than ground-based methods or single scenes of TerraSAR-X.

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Rupture process of theM_w = 7.9 2015 Gorkha earthquake (Nepal): Insights into Himalayan megathrust segmentation

Cited by 194 publications

References 55 publications

Unearthed lessons of 25 April 2015 Gorkha earthquake (M_W 7.8): geotechnical earthquake engineering perspectives

Unearthed lessons of 25 April 2015 Gorkha earthquake (M_W 7.8): geotechnical earthquake engineering perspectives

The 2015 April 25 Gorkha (Nepal) earthquake and its aftershocks: implications for lateral heterogeneity on the Main Himalayan Thrust

First Results from Sentinel-1A InSAR over Australia: Application to the Perth Basin

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Rupture process of theMw = 7.9 2015 Gorkha earthquake (Nepal): Insights into Himalayan megathrust segmentation

Cited by 194 publications

References 55 publications

Unearthed lessons of 25 April 2015 Gorkha earthquake (MW 7.8): geotechnical earthquake engineering perspectives

Unearthed lessons of 25 April 2015 Gorkha earthquake (MW 7.8): geotechnical earthquake engineering perspectives

The 2015 April 25 Gorkha (Nepal) earthquake and its aftershocks: implications for lateral heterogeneity on the Main Himalayan Thrust

First Results from Sentinel-1A InSAR over Australia: Application to the Perth Basin

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Rupture process of theM_w = 7.9 2015 Gorkha earthquake (Nepal): Insights into Himalayan megathrust segmentation

Unearthed lessons of 25 April 2015 Gorkha earthquake (M_W 7.8): geotechnical earthquake engineering perspectives

Unearthed lessons of 25 April 2015 Gorkha earthquake (M_W 7.8): geotechnical earthquake engineering perspectives