Evidence of liquefaction near Baramulla (Jammu and Kashmir, India) to the 2005 Kashmir earthquake

摘要

We report here the liquefaction caused near Baramulla in Jammu and Kashmir, India due to the 8 October 2005 Kashmir earthquake (Mw 7.6). Study of the liquefaction phenomenon and features caused due to earthquakes is vital for earthquake hazard assessment and palaeoseismology. From the analysis of worldwide earthquake and liquefaction data, it has been observed that an earthquake of magnitude as low as of 5, but more commonly of magnitude higher than 5.5 can produce liquefaction1. Also, liquefaction occurs under favourable geological and ground-water conditions and is generally widespread due to large and great earthquakes2. Liquefaction occurs when the water saturated sandy layer is overlain by confining medium like clay or silt. During an earthquake, shear stress built-up pore water pressure results in the cohesionless sediments and this leads to liquefaction. Liquefaction during earthquake shaking3 most commonly originates at a depth ranging from a few metres to about 10m. Water and sediment mixture erupts suddenly and violently to the surface through pre-existing cracks and fissures or through fractures opened in the capping material in response to seismic shaking. Detailed description and mechanism is described by Obermeier3.