Recurring emergence of the mud islands on shelf of the Arabian Sea along the Makran coast of Pakistan – Historical perspective using remote sensing techniques

• Published in: Journal of the Geological Society of India Vol. 90; no. 2; pp. 201 - 208
• Main Authors: Kassi, Akhtar M., Bayraktar, Huseyin, Khan, Shuhab D., Kasi, Aimal K.
• Format: Journal Article
• Language: English
• Published: Springer India Geological Society of India 01-08-2017; Springer Nature B.V
• Subjects: Coastal environments; Compacting; Earth and Environmental Science; Earth Sciences; Earthquakes; Emergence; Erosion; Fluidizing; Gases; Geology; Hydrogeology; Islands; Landsat; Landsat satellites; Methane; Mud; Mud volcanoes; Remote sensing; Satellite imagery; Seismic activity; Slurries; Tectonics; Vents; Volcanoes; Arabian Sea; Pakistan
• ISSN: 0016-7622; 0974-6889
• DOI: 10.1007/s12594-017-0700-1

Recurring emergences of mud islands on shelf of the Arabian Sea, along the Makran coast of Pakistan are now known to be submarine mud volcanoes. They are expressions of enhanced extrusions of fluidized mud and gases coupled with compressional tectonics in convergent margin settings. Since 1945 the Malan island has emerged four times, and some other mud islands have also been emerging repeatedly, at their own positions.
The first known emergence, during November 1945, was concurrent with an earthquake of magnitude 8.0 (M8.0), the 2
nd
and 3
rd
emergences, in March 1999 and November 2010 respectively, were not related apparently with earthquakes. The 4
th
emergence concurred with the Awaran earthquake (M7.7) of 24th September 2013. Landsat images of March 1999 and November 2010 emergences indicate appearance of round-shaped island of 4.4 and 5.2 hectare area, followed by erosion and disappearance. The island was composed of mud breccias and circular vents spewing mud slurry and methane gas.
The emergence of Malan island, in March 1999 and November 2010 was compared with earthquake data before and after the emergences. The earthquakes data, two years before March 1999 and November 2010 emergences and two years afterwards, shows correlation with both small and large earthquakes, prior to the emergence, in the radius of over 400 km. It is proposed that mud islands develop in response to the episodes of enhanced mud extrusion, which inturn are related with the enhanced compressional and/or seismic events. These events are followed by periods of relative quiescence characterized by normal activity of mud extrusion and marine erosion.