KARACHI, Oct 22: The island that had emerged from the sea off the Gwadar coast last month following an earthquake has reduced in size and is facing fast erosion, experts at the National Institute of Oceanography (NIO) told Dawn on Tuesday.

They added that visible changes in the island size were noticed during a survey by a team of NIO experts on Monday.

“The island has gone 10 feet down under water. The muddy areas of the island are fast eroding,” said principal scientific officer at the NIO Dr Asif Inam.

According to the NIO, the island (just over a kilometre from the shore) was 50 metres long, 20 metres wide and 10 metres above sea level.

Sources said the team’s visit to the island followed a communication from Nasa (National Aeronautics and Space Administration) whose satellite images showed the sand deposition earlier present around the island disappeared.

“The island would likely collapse and vanish after some time because of strong wave action and gradual easing out of gas pressure that had created it,” Dr Inam explained.

Samples of rock, water and sediments collected from the island were being analysed at the institute’s laboratory in Karachi and would be completed by next month, the principal scientific officer said.Earlier, at least three islands had been reported in the same area, one in 1945 and the others in 1999 and 2010.

The emergence of islands this year and the one in 1945 had followed massive earthquakes in the onshore area of Makran.

Last month the earthquake had also led to the formation of at least three landmasses near Ormara. The landmasses, according to the experts, were not islands rather extrusions, as they failed to properly emerge from the surface of water.

The landmasses were located about 15km offshore in deep waters.

According to scientists, the Makran coastal belt is reported to have extensive reserves of frozen methane that exist in the form of gas hydrates (crystalline water-based solids physically resembling ice, formed under conditions of relatively high pressures and low temperatures) hundreds of metres below the seafloor. And whenever this highly pressurised gas finds a weak space to release some of its energy, a dome-like structure (island) is created within the waters or it emerges from the sea.

The space to release energy can be formed due to tectonic movements, creating some fractures and fissures in the strata. Sometimes such structures do not emerge from the sea and go unnoticed.

Dr Inam said: “It’s an active seismic region where three tectonic plates — Indian, Eurasian and Arabian — are converging. The area is required to be mapped in detail to ascertain the potentially hazardous parts. Besides, the area can be explored to overcome energy crisis.”