Indian scientists discover active submarine volcano in Andaman sea

Subject: Geography

Section: Physical geography

Context:

Two Indian scientists and their team from the National Institute of Oceanography (NIO), have discovered an active submarine volcano (Crater Seamount) in the Andaman Sea, which has been at the epicenter of the seismic zone since it was first observed in 2007.
Crater Seamount has the potential to erupt at any time leading to earthquakes and even tsunamis in the Java-Sumatra region.

Details:

The CSIR-NIO conducted a groundbreaking high-resolution multi-beam echo-sounding (MBES) survey in 2004 over the earthquake swarm region, unveiling the presence of well-developed twin submarine volcanoes.
- A multibeam echo sounder (MBES) is a type of sonar that is used to map the seabed.
In 2014 they conducted the Ocean Bottom Seismometer (OBS) survey aimed at monitoring the volcanic arc.
- An ocean-bottom seismometer (OBS) is a seismometer that is designed to record the earth motion under oceans and lakes from man-made sources and natural sources.
They detected the presence of two gas flares on the outer flanks of the cratered seamount that provided the evidence of presence of active volcanism in the region.

Earthquake swarms:

In seismology, an earthquake swarm is a sequence of seismic events occurring in a local area within a relatively short period. The time span used to define a swarm varies, but may be days, months, or years.
Such an energy release is different from the situation when a major earthquake (main shock) is followed by a series of aftershocks: in earthquake swarms, no single earthquake in the sequence is obviously the main shock. In particular, a cluster of aftershocks occurring after a mainshock is not a swarm.

Crater seamount:

A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface (sea level), and thus is not an island, islet, or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to 1,000–4,000 m (3,300–13,100 ft) in height.

Andaman-Nicobar Volcanic arc:

The Andaman-Nicobar Basin has evolved through a complex history of tectonics associated with the convergent plate boundaries between Indian plate and west Burmese plate.
The Andaman-Nicobar basin was initiated with the northward drift of the Indian Plate with respect to Asia. The collision of Indian/Eurasian plates initiated along the irregular boundary and occurred at the same time as the oceanic subduction beneath southern Eurasia.
The continental collision slowed down the oceanic spreading rates in the Indian Ocean and slowed down the subduction velocity along the Sunda Arc system. It resulted in a phase of extension in the adjacent Fore-Arc and Back-Arc areas.
Major Tectonic elements of Andaman-Nicobar region are:
- Andaman Trench/Inner slope
- Outer High/Trench slope break
- Fore Arc Basin
- Volcanic Arc
- Back Arc Basin
- Mergui Terrace