Paleoseismological Findings at a New Trench Indicate the 1714 M8.1 Earthquake Ruptured the Main Frontal Thrust Over all the Bhutan Himalaya

Zhao, Yongmei; Grujić, Djordje; Baruah, Santanu; Drukpa, Dawchu; Elkadi, Joanne; Hetényi, György; King, Georgina E.; Mildon, Zoë; Nepal, Nityam; Welte, Caroline

doi:10.3389/feart.2021.689457

Cited by 13 publications

(6 citation statements)

References 85 publications

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“…Poor constructed infrastructure and steep topography caused the major devastation in the region during the 2006 and 2011 earthquake events (Rai et al, 2012; Sengupta et al, 2010). In the eastern side, Bhutan region falls in the seismically shadow zone (Gahalaut et al, 2011) and no large detachment earthquakes were reported after 1714 Bhutan Earthquake (Zhao et al, 2021). The 2011 earthquake occurred along the strike‐slip fault, therefore it could not decrease the risk from the terrific Himalayan earthquakes, which can be anticipated to arise at the detachment (Gahalaut, 2011), whereas no large detachment triggered earthquake has occurred after 1100 AD in the Sikkim Himalaya (Kumar et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

Co‐seismic landslides in the Sikkim Himalaya during the 2011 Sikkim Earthquake: Lesson learned from the past and inference for the future

Joshi

2022

Geological Journal

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Sikkim, a north‐eastern state of India, has a very specific and unique place in the tourism map of India. Every year, lakhs of people visit the state. To accommodate such floating population in the area, some big towered home stays/hotels have been constructed. However, the area is under the threat of many natural disasters such as earthquake, landslide, land subsidence, cloudburst, etc. In the year 2021, within a span of 8 months (April–November), the Sikkim state hosted four light to moderate earthquakes (Mw 4.1–Mw 5.1). Out of these, the strongest earthquake (Mw 5.1) occurred on 5 April 2021, which was well experienced in the parts of Indian states (i.e., Sikkim, West Bengal, Bihar) and across International borders, viz Bangladesh, Nepal, Bhutan, and China. Fortunately, this earthquake did not cause any major damage in the region. However, in the last two decades, one moderate (Mw 5.3) and one strong earthquake (Mw 6.9) has occurred in the Sikkim region on 14 Feb 2006 and 18 September 2011, respectively. Both of these earthquakes caused well enough damage to the residential as well as commercial buildings. Apart from infrastructural degeneracy, the 2011 Sikkim Earthquake (Mw 6.9) also caused generation of co‐seismic landslides within ~100 km epicentral distance from the earthquake. After a decade, from the 2011 earthquake, Gangtok city and other parts of the state have been rebuilt and reconstructed again, but most of the newly constructed and old refurbished buildings are established in the steep slope areas without considering the geotechnical properties of the underlying soil. These structures could be vulnerable during moderate to strong earthquakes. Therefore, the present study unfurled a question “Did we learn any lesson from the 2011 Sikkim Earthquake?”. Furthermore, the study calls for earthquake hazard adaptation measures in the tectonically sensitive Himalayan region in order to safeguard the lives and vital infrastructure.

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Section: Discussionmentioning

confidence: 99%

Co‐seismic landslides in the Sikkim Himalaya during the 2011 Sikkim Earthquake: Lesson learned from the past and inference for the future

Joshi

2022

Geological Journal

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“…Fig.8The historical occurrence of earthquakes in Assam shown in red star(Bhuyan 1933;Gait 1906;Iyengar et al 1999; Ambraseys and Jackson 2003;Rinchen, 1974;Zhao et al 2021; Poddar 1950); OSL dates ofThomas et al 2007 shown in yellow solid rectangle and black solid rectangle shows the ages of the present study. Red solid rectangles indicate the age from Sessa Nalla uplifted section.…”

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confidence: 82%

“…Fig. 8 The historical occurrence of earthquakes in Assam shown in red star (Bhuyan 1933;Gait 1906;Iyengar et al 1999;Ambraseys and Jackson 2003;Rinchen, 1974;Zhao et al 2021;Poddar 1950)…”

Section: A Field Observation and Back-calculation For Palaeomagnitudementioning

confidence: 99%

Holocene Records of Large Palaeoearthquake events from the Brahmaputra valley in the proximity of the Eastern Himalayan Syntaxis and Environmental Impacts

Bhadran

Duarah

Girishbai

et al. 2022

Preprint

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The Eastern Himalayan Syntaxis (EHS) and associated tectonic plate boundaries have caused two great earthquakes within hundred years and more than fifteen strong earthquakes (from eighteen centuries) in the foredeep Brahmaputra Basin. These earthquakes are generally considered blind, owing to the deficiency of surface rupture. Further, the lack of instrumental and historical archives elicits palaeo-seismological proxies for future seismic hazard assessment. The present study area is confined to the rapidly growing Dibrugarh City, lies on left bank of Brahmaputra and bounded by EHS in northeast, Main Frontal Thrust (MFT) in North, Naga Thrust (NT) in Southeast and Mishmi Thrust (MT) in east. This tectonically active area witnessed dreadful damages during the 1950 great Assam earthquake (Mw = 8.4), the largest continental ever recorded event. In this study, palaeoseismological evidence such as sand dyke and sand blow from different levels of the river terraces in and around Dibrugarh City has been dated using optically stimulated luminescence (OSL) methodology to understand the ages of the causative event. The optical dates from the palaeoliquefacton features indicate multiple episodic events ca. 888 ± 63 yrs, ca. 934 ± 63 yrs & ca. 989 ± 83 yrs. On the other hand, an age of ca. 11.3 ± 0.7 ka, early Holocene has been obtained from a neotectonic scarp indicates the crustal shortening time during MFT orogeny. Further, the empirical back-calculation of the complex geometry of the palaeoliquefaction feature facilitated in determining the causative earthquake magnitude and PGA, which is first of its kind from northeast of India. Back-calculation indicates, the magnitude of the earthquake might be range from 6.2-7.4Mw with PGA ~ 0.5-0.6g. The overlapping of palaeointensity lines /isoseismic lines from the empirical calculation, ESI and 1950 earthquake indicate the effect of multiple episodes of earthquake and vulnerability in Eastern Himalayan foothill areas. This study is of immense importance considering the seismic hazard potential in the eastern Himalaya and its surroundings and inadequate instrumentally recorded earthquake database.

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“…2 and 5 ) has now been well documented ( 30 , 32 – 34 ). Amid the large earthquakes that have shaken the Himalayan front in the last three centuries ( 35 ), these two events, as well as the M≈ 8.4, 1934, Bihar/Nepal earthquake ( 36 – 38 ) and the M≈ 8, 1714, Bhutan Earthquake ( 39 ) ( Fig. 6 C ), are among the few that indisputably ruptured the surface.…”

Section: Geodetic and Seismic Constraints On The Kinematics Of Recent...mentioning

confidence: 99%

The shape of the Himalayan “Arc”: An ellipse pinned by syntaxial strike-slip fault tips

Jiao,

Tapponnier,

Coudurier-Curveur Mccallum

et al. 2024

Proc. Natl. Acad. Sci. U.S.A.

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Trans-Himalayan geodetic data show that, between both syntaxes, India/Asia convergence is steadily oriented ≈ N20°E. However, surface faulting near both syntaxes, along the 2005 and 1950 earthquake ruptures, imply long-term thrusting directed ≈ 130° apart, and post-LGM (last Glacial Maximum) shortening rates of ≈ 5 to 6 mm/y, ≈ 2 to 3 times slower than in Nepal (≈ 15 to 20 mm/y). Syntaxial earthquakes’ return-time are also ≈ 3 times longer (>2,000 y) than in Nepal (≈ 700 y). In a structural frame centered halfway between the syntaxial cusps, the tectonic features of the range show remarkable symmetry. In map view, the overall shapes of the Main Front Thrust (MFT) and the Main Central Thrust (MCT) closely fit ellipses, with major-to-minor axis ratios of ≈ 2.5 to 3. This suggests that the range growth atop subducting India is “pinned” by the strike-slip faults that bound it to the east and west. Discrete Element Modeling corroborates a late-Tertiary elliptical range growth. This accounts for the ≈ 65° angles and twofold to threefold decrease in active thrusting between Nepal and the syntaxes, for the maximum Himalayan heights (≥8,000 m), larger magnitudes (≥8), and shorter return-time (≈ 700 y) of great earthquakes in Nepal, for the existence of two 500- to 600 km-long, south-concave mountain ranges north of both syntaxes and for the ≈ 9 mm/y, N100 to 110°E extension across southern Tibet. It also suggests that predictions of impending or frequent great earthquakes in the eastern- and westernmost Himalayas may be overstated.

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Paleoseismological Findings at a New Trench Indicate the 1714 M8.1 Earthquake Ruptured the Main Frontal Thrust Over all the Bhutan Himalaya

Cited by 13 publications

References 85 publications

Co‐seismic landslides in the Sikkim Himalaya during the 2011 Sikkim Earthquake: Lesson learned from the past and inference for the future

Co‐seismic landslides in the Sikkim Himalaya during the 2011 Sikkim Earthquake: Lesson learned from the past and inference for the future

Holocene Records of Large Palaeoearthquake events from the Brahmaputra valley in the proximity of the Eastern Himalayan Syntaxis and Environmental Impacts

The shape of the Himalayan “Arc”: An ellipse pinned by syntaxial strike-slip fault tips

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