Intensity estimation for the 2001 Bhuj earthquake, India on ESI-07 scale and comparison with historical 16th June 1819 Allah Bund earthquake: A test of ESI-07 application for intraplate earthquakes

Abstract

On 26th January 2001, an earthquake of magnitude Mw 7.7 occurred near Bhuj, in northwestern India, resulting in severe environmental effects. No unequivocal primary surface rupture was observed for the earthquake, but it caused widespread liquefaction and lateral spreading in the Rann of Kachchh and Little Rann. After the earthquake, several researchers collected field evidence of secondary surface rupture, rockfall, dry craters, and surface manifestations of liquefaction, including the formation of mud volcanoes and lateral spreads, in the meizoseismal area. Analysis of pre- and post-earthquake satellite images suggests that several “dry” streams in the Rann of Kachchh began to flow due to extensive liquefaction induced by the earthquake. In this present study, the macroseismic intensity of the Bhuj earthquake is evaluated by considering these environmental effects and applying the ESI-07 intensity scale to the affected area. As an outcome, the epicentral intensity of the 2001 Bhuj earthquake was determined to be XI. According to historical records and seismic catalogs, 16th June 1819 Allah Bund earthquake caused prominent surface rupture which was not so clear in the case of 2001 Bhuj earthquake, but the secondary effects were similar for both earthquakes. Considering the environmental effects caused by the 1819 Allah Bund earthquake, an intensity of XI was estimated for the epicentral area. For both earthquakes, the ESI scale yields a significant difference of one to two degrees with the traditional intensity scales. The 2001 Bhuj earthquake and 1819 Allah Bund earthquake shows similar ESI-07 intensity of XI despite of different epicentral locations. This implies the reliability of ESI-07 scale application for different earthquakes of similar dimensions in the same geological setting. This study contributes to the application of ESI-07 scale for Indian earthquakes, especially reverse faulting events, and to the future improvement of the ESI scale with emphasis on its applicability to historical earthquakes on the Indian subcontinent. Also, this study may help in future land use planning in the meizoseismal area of 1919 Allah Bund and 2001 Bhuj earthquakes