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

Abstract

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.

Debris Flow Classification and Risk Assessment Based on Combination Weighting Method and Cluster Analysis: A Case Study of Debris Flow Clusters in Longmenshan Town, Pengzhou, China

“…(5) Calculate the cluster center. (6) The maximum number of cycles is reached, and the final result is obtained.…”

“…Due to the characteristics of high density, strong fluidity, and fast flow velocity, debris flows are highly destructive. In recent years, frequent debris flows have significantly harmed human life, property, the economy, and the environment, especially in mountainous areas' seismic and geological active zones [4][5][6]. The CMLR (Chinese Ministry of Land and Resources) reports that thousands of disasters occur yearly in China, and mountainous hazards threaten 74 million people.…”

Introduction, Part 2—Geodynamic evolution of Eastern Himalaya and Indo‐Myanmar orogenic belts: Advances through interdisciplinary studies

“…Joshi (2022) gives a detailed account of the earthquake‐induced landslides in the Sikkim Himalaya, due to the 2011 earthquake. It discusses the earthquakes that occurred in the Sikkim region on 14 February 2006 (Mw 5.3) and 18 September 2011(Mw 6.9), respectively during the last two decades.…”

“…Geological map of Eastern Himalaya, Indo‐Myanmar orogenic belt, northern, Central Myanmar, and adjacent areas (modified after Mitchell et al, 2007; Searle et al, 2007; Y. R. Singh, Singh, Singh, et al, 2022). Locations of study area presented in the issue include 1/S2: Kundu and Hazarika (2022); 2/S2: Y. R. Singh, Singh, Singh, et al (2022); 3/S2: Rawat and Luirei (2022); 4/S2: Kayal et al (2022); 5/S2: Choudhury et al (2022); 6/S2: N. M. Sharma et al (2022); 7/S2: Goswami, Gogoi, et al (2022); 8/S2: Bikramaditya et al (2022); 9/S2: Goswami, Kalita, et al (2022); 10/S2: Joshi (2022); 11/S2: Jha and Sharma (2022); 12/S2: Shukla et al (2022); 13/S2: Khonglah et al (2022); 14/S2: Ali and Duarah (2022); 15/S2: Mohanty et al (2022); 16/S2: Chanu et al (2022); 17/S2: Majumdar, Gogoi, and Ghatak (2022); Majumdar, Gogoi, Ghatak, Saikia, et al (2022); 18/S2: Ding et al (2022); 19/S2: Ghose et al (2022); 20/S2: Hussain and Dey (2022); 21/S2: Ozukum et al (2022); 22/S2: Jamir et al (2022); 23/S2: Chaubey et al (2022); 24/S2: Bora, Borah, et al (2022); Bora, Mukherjee, et al (2022); 25/S2: Khuman and Ibotombi (2022); 26/S2: Y. R. Singh, Singh, Singh, et al (2022); 27/S2: Thokchom and Kshetrimayum (2021); 28/S2: Barman et al (2022); 29/S2: V. Sharma and Biswas (2022)…”