Seismic Zones and Faults: Earthquake Hazard in Rajasthan

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Seismic Zones and Faults: Earthquake Hazard in Rajasthan: Rajasthan is divided into two seismic zones, Zone II and Zone III, as per the Bureau of Indian Standards (BIS) seismic zoning map of India.

  • Zone II: This zone is considered to be a low-intensity seismic zone. The maximum expected Modified Mercalli Intensity (MMI) in this zone is VI. Districts in Zone II include Jaipur, Jodhpur, Ajmer, Bikaner, Churu, Jaisalmer, Nagaur, Pali, and Sirohi.
  • Zone III: This zone is considered to be a moderate-intensity seismic zone. The maximum expected MMI in this zone is VII. Districts in Zone III include Alwar, Bharatpur, Baran, Bundi, Dausa, Dholpur, Dungarpur, Hanumangarh, Jhalawar, Karauli, Kota, Pratapgarh, Rajsamand, Sawai Madhopur, Tonk, and Udaipur.
  • The major faults in Rajasthan include:
  • Great Boundary Fault (GBF): The GBF is a major tectonic fault that runs along the western margin of the Aravalli Range. It is a strike-slip fault, meaning that the movement along the fault is horizontal. The GBF is considered to be capable of generating earthquakes of magnitude 6.5 or greater.
  • Delhi-Aravalli Fold Belt (DAFB): The DAFB is a zone of folding and faulting that extends from Delhi to the Aravalli Range. It is a complex zone of deformation that is capable of generating earthquakes of magnitude 6 or greater.
  • Son-Narmada Lineament (SNL): The SNL is a major tectonic lineament that extends from the Son River to the Narmada River. It is a zone of weakness in the Earth’s crust that is capable of generating earthquakes.

Seismic Zones & Earthquake Hazard in Rajasthan

The earthquake hazard in Rajasthan is considered to be moderate. The state has experienced a number of damaging earthquakes in the past, including the 1956 M 6.7 Anjar earthquake, the 1969 M 6.3 Bhuj earthquake, and the 2001 M 6.9 Bhuj earthquake.

The areas of Rajasthan that are considered to be at the highest risk of earthquakes are the districts of Alwar, Bharatpur, Baran, Bundi, Dausa, Dholpur, Dungarpur, Hanumangarh, Jhalawar, Karauli, Kota, Pratapgarh, Rajsamand, Sawai Madhopur, Tonk, and Udaipur. These districts are located in Seismic Zone III.

The areas of Rajasthan that are considered to be at a lower risk of earthquakes are the districts of Jaipur, Jodhpur, Ajmer, Bikaner, Churu, Jaisalmer, Nagaur, Pali, and Sirohi. These districts are located in Seismic Zone II.

Earthquake History

  • Though the state of Rajasthan has not had a major earthquake in recent years, small to moderate earthquake have been felt in the state.
  • Several faults have been identified in this region out of which many show evidence of movement during the Holocene epoch.
  • The Cambay Graben terminates in the south-western part of the state. The Konoi Fault near Jaisalmer trends in a north-south direction and was associated with the 1991 Jaisalmer earthquake. Several active faults criss-cross the Aravalli range and lie parallel to each other.
  • The most prominent of them is the north-south trending Sardar Shahr Fault and the Great Boundary Fault which runs along the Chambal River and then continues in the same direction into Uttar Pradesh.
  • However, it must be stated that proximity to faults does not necessarily translate into a higher hazard as compared to areas located further away, as damage from earthquakes depends on numerous factors such as subsurface geology as well as adherence to the building codes.

According to GSHAP data, the state of Rajasthan falls in a region of moderate to high seismic hazard. As per the 2002 Bureau of Indian Standards (BIS) map, Rajasthan falls in Zones II, III & IV. Historically, parts of this state have experienced seismic activity in the M 5.0 range.

Largest Instrumented Earthquake in Rajasthan

  1. 15 August 1906 – Thar Desert, Rajasthan, Mw 6.2
  2. This event was located along the India-Pakistan border, in the vicinity of Janpalia, Rajasthan which is located north-northwest of Bakhasar.

Seismic Faults in Rajasthan

  • Several faults have been identified in Rajasthan, out of which many show evidence of movement during the Holocene epoch.  
  • The Cambay Graben terminates in the south-western part of the state.
  • The Konoi Fault near Jaisalmer trends in a north-south direction and was associated with the 1991 Jaisalmer earthquake.
  • Several active faults criss-cross the Aravalli range and lie parallel to each other.
  • The most prominent of them is the north-south trending Sardar Shahar Fault and the Great Boundary Fault which runs along the Chambal River and then continues in the same direction into Uttar Pradesh.

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