1897 Assam earthquake

The Assam earthquake of 1897 occurred on 12 June, 1897, in Assam, India at 17:15 IST, and had an estimated moment magnitude of 8.0. It resulted in approximate 1,542 human casualties and caused catastrophic damage to infrastructure. Damage from the earthquake extended into Calcutta, where dozens of buildings were severely damaged, with some buildings partially collapsing. Trembles were felt across India, reaching as far as Ahmedabad and Peshawar. Seiches were also observed in Burma.[2]

1897 Assam earthquake
1897 Assam earthquake is located in India
1897 Assam earthquake
Local date12 June 1897 (1897-06-12)
Local time17:15[1]
Magnitude8.0 Mw[1]
Epicenter26°N 91°E / 26°N 91°E / 26; 91Coordinates: 26°N 91°E / 26°N 91°E / 26; 91
Areas affectedIndia
Max. intensityX (Extreme)[1]
Casualties1,542[2]
Map showing the epicentre and the areas affected by the 1897 earthquake[3]

EarthquakeEdit

The earthquake occurred on the SSW-dipping reverse Oldham fault that forms the northern edge of the Shillong Plateau within the Indian Plate.[4][5] There was a minimum displacement on the main fault of 11 m, although some calculations have placed this figure at as high as 16 m, one of the greatest for any measured earthquake.[4] The calculated area of slip extended 180 km along strike and from 9–45 km below the surface, indicating that the entire thickness of the crust was involved.

DamageEdit

 
Government House in Shillong before and after the earthquake[3]

Thought to have happened 32 km underground, the earthquake left masonry buildings in ruins over 400,000 km2 area and was felt over 650,000 km2 from Burma to Delhi. Numerous buildings in the neighboring country of Bhutan were heavily damaged.[6] Dozens of aftershocks were felt in and around the region with the last event being felt on 9 October 1897 at 01:40 UT in Calcutta.[2]

The earthquake resulted in Shillong Plateau being thrust violently upwards by about 11  meters. The fault was about 110  km in length while the fault slip was about 18 m (accuracy more or less by 7 m). At the epicenter, vertical acceleration is thought to have been above 1g force and surface velocity 3 m/s.[7]

 
Earthquake damage to a bridge on the East Bengal Railway[3]

In Shillong, the earthquake damaged every stone house and half the houses built of wood.[3]:5 The shock leveled the ground and resulted in 13 deaths. The fissure was also reported in the area. In Sohra Cherrapunji, it resulted in a landslide, which led to 600 deaths.[8] In Goalpara, it resulted in waves from the river Brahmaputra, on which bank the town is situated, destroying the market.[8] In Nalbari, there were reported sightings of earth-waves and water waves. In Guwahati, the earthquake lasted for 3 minutes. the Brahmaputra river rose by 7.6  ft. Damage was caused to Umananda Island temple and railway lines. 5 people died.[8] In Nagaon, every brick house was damaged, while traditional houses made of wood, with grass roofs, were bent. There were many small fissures/volcanos and the road was impassable for vehicles.[8]

In the Sylhet region, shocks took place at 16:30, according to villagers living at the foot of the hills north of Sunamganj. There were 545 casualties. 55 in Sylhet town, 178 in North Sylhet, 287 in Sunamganj, 7 in Habiganj, 8 in South Sylhet and 10 in Karimganj. Many buildings collapsed and fissures and drowning furthered the amount of deaths. A woman in Sunamganj is said to have fell through a fissure whilst on a river with her husband. The husband tried to hold onto her hair but lost hold of her. The woman's body was not recovered from the crevasse. The Assam Bengal Railway was severely damaged.[9][10][3]:295-298

Richard Dixon Oldham, the Superintendent of the Geological Survey of India, analysed seismic records of the earthquake, mainly from stations in Italy, and reported the first clear evidence of different type of seismic waves, travelling through the earth on different paths and at different speeds.[3]:227-256

See alsoEdit

ReferencesEdit

  1. ^ a b c National Geophysical Data Center / World Data Service (NGDC/WDS) (1972), Significant Earthquake Database (Data Set), National Geophysical Data Center, NOAA, doi:10.7289/V5TD9V7K
  2. ^ a b c "Documentation on past disasters, their impact, Measures taken, vulnerable areas in Assam" (PDF). Archived from the original (PDF) on 11 July 2015. Retrieved 29 April 2015.
  3. ^ a b c d e f Oldham, R. D. (1899). "Report of the great earthquake of 12th June, 1897". Memoirs of the Geological Society of India. K. Paul, Trench, Trübner & co. 29.
  4. ^ a b Bilham, Roger; England, Philip (2001). "Plateau 'pop-up' in the great 1897 Assam earthquake". Nature. 410 (6830): 806–809. Bibcode:2001Natur.410..806B. doi:10.1038/35071057. PMID 11298446.
  5. ^ Hough, S.E.; Bilham, R.; Ambraseys, N.; Feldl, N. (2005). "Revisiting the 1897 Shillong and 1905 Kangra earthquakes in northern India: Site response, Moho reflections and a triggered earthquake" (PDF). Current Science. 88 (10): 1632–1638.
  6. ^ Kalita, Jugal. "The Great Assam Earthquake of 1897". Assam Portal.
  7. ^ Bilham, Roger; England, Philip (2001). "Plateau 'pop-up' in the great 1897 Assam earthquake". Nature. 410 (6830): 806–809. Bibcode:2001Natur.410..806B. doi:10.1038/35071057. PMID 11298446.
  8. ^ a b c d "The Great Assam Earthquake of 1897 | Assam Portal".
  9. ^ B C Allen (1905). "Physical Aspects". Assam District Gazetteers: Sylhet. 2. Calcutta: Government of Assam. p. 13–16.
  10. ^ Anderson, Francis Philip (1900). "The effects of the earthquake in 1897 on the Shaistaganj division of the Assam-Bengal Railway". Minutes of the Proceedings of the Institution of Civil Engineers. 141: 258–261.

Further readingEdit

External linksEdit