The 2015 Gorkha earthquake investigated from radar satellites: slip and stress modeling along the MHT

Diao, Faqi; Walter, Thomas R.; Motagh, Mahdi; Prats-Iraola, Pau; Wang, Rongjiang; Samsonov, Sergey

doi:10.3389/feart.2015.00065

Cited by 29 publications

(26 citation statements)

References 25 publications

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“…The earthquake was well recorded by modern geodetic measurements [ Galetzka et al , ; Feng et al , ], providing us with an unprecedented opportunity to investigate the variations in dip. The overall fault dip is estimated to be approximately 6–11° based on seismic and geodetic analyses [ Avouac et al , ; Diao et al , ; Hayes et al , ; Liu and Ge , ; Shan et al , ; Wang and Fialko , ; Wang et al , ; Zhang and Xu , ; Zhang et al , ; Liu et al , ], suggesting that the earthquake mainly ruptured a flat portion of the MHT. Some geodetic analyses found that a listric fault could explain the surface deformations better than a planar fault could [ Wang and Fialko , ; Elliott et al , ], implying that ruptures may have reached the shallow steep fault branches.…”

Section: Introductionmentioning

confidence: 99%

Significant lateral dip changes may have limited the scale of the 2015 M_w 7.8 Gorkha earthquake

Yong

Wang

Walter

et al. 2017

Geophysical Research Letters

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The 2015 Mw 7.8 Gorkha earthquake has drawn interest due to its complex fault geometry. Both geodetic and geologic studies have focused on the dip variations. In this study we invert the coseismic geodetic data for the 2‐D dip variations of the earthquake. The best fit model confirms that the dip varies with depth, and suggests that there is a significant lateral dip anomaly along strike. The depth‐dependent dip variation suggests that the earthquake ruptured a ramp‐flat fault. The shallow ramp may have prevented the rupture breaking through the surface. In addition, a lateral large‐dip anomaly is found in the northeastern corner of the slip area, which supports the previous findings of inferred interseismic fault coupling, coseismic high‐frequency radiations, and the aftershock mechanisms. This lateral dip anomaly is likely associated with local tearing within the Indian slab. It may have blocked the east‐southeastward rupture propagations of the Gorkha earthquake, implying important controls on the earthquake scale and the spatial limits of ruptures.

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Section: Introductionmentioning

confidence: 99%

Significant lateral dip changes may have limited the scale of the 2015 M_w 7.8 Gorkha earthquake

Yong

Wang

Walter

et al. 2017

Geophysical Research Letters

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“…The result shows that the 14-day revisit cycle of the ALOS-2 successfully separated the main shock and the aftershock. These interferometric pairs are analyzed and discussed more precisely in Diao et al (2015), Kobayashi et al (2016), Lindsey et al (2016), and Wang and Fialko (2015). Especially, Kobayashi et al (2016) use both ScanSAR-ScanSAR and StripmapScanSAR interferometry, that we will discuss in the next a b section, for modeling the deformation and the fault rupture.…”

Section: Subtracting Remaining Non-crustal Fringesmentioning

confidence: 99%

SAR interferometry using ALOS-2 PALSAR-2 data for the Mw 7.8 Gorkha, Nepal earthquake

Natsuaki

Nagai

Motohka

et al. 2016

Earth Planets Space

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The Advanced Land Observing Satellite-2 (ALOS-2, "DAICHI-2") has been observing Nepal with the Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) in response to an emergency request from Sentinel Asia related to the Mw 7.8 Gorkha earthquake on April 25, 2015. PALSAR-2 successfully detected not only avalanches and local crustal displacements but also continental-scale deformation. Especially, by the use of the ScanSAR mode, we are able to make interferograms that cover the entire displacement area of the earthquake. However, we did encounter some fundamental problems with the ScanSAR and incorrect settings of PALSAR-2 operation that have now been fixed. They include (1) burst overlap misalignment between two ScanSAR observations, which limits the number of pairs available and the quality of the interferogram, (2) non-crustal fringes which are derived from co-registration error and/or ionospheric effect and, (3) incorrect setting of the center frequency in the Stripmap beam F2-6. In this paper, we describe their problems and solutions. The number of interferometric pairs are limited by (1) and (3). The accuracy of the interferograms are limited by (2) and (3). The experimental results showed that current solutions for (2) and (3) work appropriately.

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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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The 2015 Gorkha earthquake investigated from radar satellites: slip and stress modeling along the MHT

Cited by 29 publications

References 25 publications

Significant lateral dip changes may have limited the scale of the 2015 M_w 7.8 Gorkha earthquake

Significant lateral dip changes may have limited the scale of the 2015 M_w 7.8 Gorkha earthquake

SAR interferometry using ALOS-2 PALSAR-2 data for the Mw 7.8 Gorkha, Nepal earthquake

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

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The 2015 Gorkha earthquake investigated from radar satellites: slip and stress modeling along the MHT

Cited by 29 publications

References 25 publications

Significant lateral dip changes may have limited the scale of the 2015 Mw 7.8 Gorkha earthquake

Significant lateral dip changes may have limited the scale of the 2015 Mw 7.8 Gorkha earthquake

SAR interferometry using ALOS-2 PALSAR-2 data for the Mw 7.8 Gorkha, Nepal earthquake

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

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Significant lateral dip changes may have limited the scale of the 2015 M_w 7.8 Gorkha earthquake

Significant lateral dip changes may have limited the scale of the 2015 M_w 7.8 Gorkha earthquake