Regional variation of stress level in the Himalayas after the 25 April 2015 Gorkha earthquake (Nepal) estimated using<i>b</i>-values

Pudi, Ramesh; Martha, Tapas R.; Kumar, K. Vinod

doi:10.1088/1742-2140/aaa26c

Cited by 8 publications

(3 citation statements)

References 36 publications

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“…Chandrani et al [ 23 ] also concluded that the b -value decreased with depth. According to Liu et al [ 24 ], in the Longmenshan area, the b -value showed a significant boundary above 15 km where b -values were higher. Below this depth, the b -value decreased.…”

Section: Previous Studies Of B -Value In Tibetmentioning

confidence: 99%

“…The only earthquake with a magnitude greater than 8 (shown in Table 1 ) in the study area was the Gorkha earthquake (28.15° N, 84.65° E), which happened on 25 April 2015 and had a focal depth of 20 km (recorded by the China Earthquake Networks Center). According to the U.S. Geological Survey, the magnitude of the Gorkha earthquake was 7.8 [ 24 ].…”

Section: Earthquake Datamentioning

confidence: 99%

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Spatial Variation of b-Values and Their Relationship with the Fault Blocks in the Western Part of the Tibetan Plateau and Its Surrounding Areas

Hussain

Zhang

Usman

et al. 2020

Entropy

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The Tibetan Plateau is considered to be one of the best natural laboratories for seismological research. This study sought to determine the spatial variations of b-values in the western part of the Tibetan Plateau, along with its surrounding areas, and the relation with the region’s fault blocks. The study region lies within 27–36.5° N, 78–89° E, and its fracture structure consists of strike-slip faults, as well as normal and thrust faults. A catalog record from 2009–2019 provided 4431 well-centered earthquakes that varied in magnitude from 0.1 to 8.2 M. The record was obtained from China’s seismological network, which is capable of recording low magnitudes to analyze b-values in the study area. The key findings of this study are as follows: (1) the range of earthquake depth in the region was 0–256 km, with the depth histogram showing a high frequency occurrence of shallow earthquakes in the area; (2) a time histogram showed that the major earthquakes occurred between 2014–2015, including the notable 2015 Gorkha earthquake (M = 8.2); (3) the b-value computed in the study area was 0.5 to 1.6, but in most of the study area, the b-value ranged from 0.6 to 0.9, which was a low to intermediate value, due to the presence of strike-slip faults in the central part of the study area and underthrusting in the region (south of the study area); and (4) a high b-value was found in the northwestern and eastern regions of the area, which proved that the area is prone to small earthquakes in the near future. The study also showed that the central and southern areas of the study region had low to intermediate b-values, meaning that it is prone to destructive and massive earthquakes with high magnitudes, such as the Gorkha earthquake (southern part of the study area). Low b-values revealed the degree of variation in rock properties, including large stress and strain, a fractured medium, a high deformation rate, and large faults. Small b-values were observed when the stress level was high in the investigated region, which might be used to predict a massive high-magnitude earthquake in the near future.

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Section: Previous Studies Of B -Value In Tibetmentioning

confidence: 99%

Section: Earthquake Datamentioning

confidence: 99%

Spatial Variation of b-Values and Their Relationship with the Fault Blocks in the Western Part of the Tibetan Plateau and Its Surrounding Areas

Hussain

Zhang

Usman

et al. 2020

Entropy

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“…A number of linear deformation zones observed by previous geophysical experiments are stated to orthogonally cut through these thrust zones (Dasgupta et al., 1987). Most of these deformation zones are characterized by dextral strike‐slip motion (Vernant et al., 2014) and some by thrusting motion (Ramesh et al., 2018), possibly causing segmentation along east‐west direction. Three major fault systems are currently known to segment the Central and Eastern Himalayas (Dal Zilio et al., 2021): Western Nepal Fault System (WFNS) (Murphy et al., 2014), Dhubri‐Chungthang Fault Zone (DCFZ) (Diehl et al., 2017) and Kopili Fault Zone (KFZ) (Lakshmi et al., 2023) (Figure 1), the former two being seismically active.…”

Section: Introductionmentioning

confidence: 99%

Complex Multi‐Fault Dynamics in Sikkim Himalaya: New Insights From Local Earthquake Analysis

Uthaman,

Singh,

Singh

et al. 2024

Geochem Geophys Geosyst

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Anomalously overturned thrust faults, lineaments and segmentation causing cross‐cutting basement structures characterize the tectonic setting of Sikkim Himalaya. However, its seismotectonics is poorly constrained along with the speculated northward extension of the Dhubri‐Chungthang Fault Zone (DCFZ) causing segmentation. Here, we utilize the precise location of newly acquired local earthquake data and fault plane solutions using full‐waveform moment tensor inversion to better constrain seismically active zones. Transtensional shearing along the Main Himalayan Thrust in central Sikkim is possibly incited by fluid‐rich upper‐crust. Cessation of the mapped 20 km wide mid‐crustal seismogenic zone of DCFZ at Chungthang and its northward discontinuation into the Higher Himalayas is confirmed by the striking variation in focal mechanisms. Earthquakes along imbricated segments in the lower‐crust originate possibly in response to crustal shortening. Extensional shearing along the Moho triggers seismicity to the northwest of Sikkim. Such complex tectonic dynamics instigating persistent seismicity indicates high potential for future great earthquakes in Sikkim Himalaya.

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Three-dimensional b-value and Fractal Dimension Mapping of the Uttarakhand Himalayan Region

Mandal

Srinagesh²,

Suresh³

et al. 2022

Journal of the Geological Society of India

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The 3-D distributions of b-value of the frequency-magnitude distribution and fractal correlation dimension (D2) of seismically active Uttarakhand Himalayan seismic zone is presented. For this study, a catalogue of 525 local earthquakes was used (ML1.0-5.5) during 2017-2020. The de-clustered catalog is found to be complete above ML=2.6. The b-value is estimated to be 0.82±0.06 by maximum likelihood method. The modelled b- and D2 estimates in the study area range from 0.35 to 1.524 and 0.29 to 1.71, respectively. The present study reveals a negative b-D2 relationship (i.e. D2=-0.008b + 1.536, with a correlation coefficient of 0.9892) with week clustering. The modeling detects two zones (viz., A, and B) of high D2 and low b-values within the MCT zone, which are defined as high hazard zones (HHZ) while zone C (in the SE part of the MCT zone) with high D2 and high b-values is detected as an intermediate hazard zone. Also, three zones (D, E and F) with low D2 and low b-values are identified as low hazard zones (LHZ), which are located away from the MCT zone. The A and B high hazard zones can accumulate high levels of tectonic stress and pose risks for generating large earthquakes in the future. But, IHZ-C represents intermediate hazard level that can generate M≥5 events in future. The mapped A and B zones are inferred to be most hazardous in the region, which correlate well with recognized seismogeneic nodes capable of M6.5+ earthquakes in the region as suggested by the geomorphological zoning using pattern recognition.

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Regional variation of stress level in the Himalayas after the 25 April 2015 Gorkha earthquake (Nepal) estimated usingb-values

Cited by 8 publications

References 36 publications

Spatial Variation of b-Values and Their Relationship with the Fault Blocks in the Western Part of the Tibetan Plateau and Its Surrounding Areas

Spatial Variation of b-Values and Their Relationship with the Fault Blocks in the Western Part of the Tibetan Plateau and Its Surrounding Areas

Complex Multi‐Fault Dynamics in Sikkim Himalaya: New Insights From Local Earthquake Analysis

Three-dimensional b-value and Fractal Dimension Mapping of the Uttarakhand Himalayan Region

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