Deep Sea Volcanic Action

Submarine volcanoes are underwater fissures in the Earth's surface from which magma can erupt. They are estimated to account for 75% of annual magma output. The vast majority are located near areas of tectonic plate movement, known as ocean ridges. Although most are located in the depths of seas and oceans, some also exist in shallow water, which can spew material into the air during an eruption. Hydrothermal vents, sites of abundant biological activity, are commonly found near submarine volcanoes. The first scientists to witness exploding rock and molten lava from a deep sea volcano, seen during a 2009 expedition, report that the eruption was near a tear in the Earth's crust that is mimicking the birth of a subduction zone. Scientists on the expedition collected boninite, a rare, chemically distinct lava that accompanies the formation of Earth's subduction zones.


Boninite is a mafic extrusive rock high in both magnesium and silica, formed typically during the early stages of subduction. The rock is named for its occurrence in the Izu-Bonin arc south of Japan.

Nobody has ever collected fresh boninite and scientists never had the opportunity to monitor its eruption before, said Joseph Resing, University of Washington oceanographer and lead author of an online article on the findings in Nature Geoscience. Earth’s current subduction zones are continually evolving but most formed 5 million to 200 million years ago. Scientists have only been able to study boninite collected from long-dead, relic volcanoes millions of years old.

Resing was chief scientist on the expedition, funded by the National Oceanic and Atmospheric Administration and the National Science Foundation, that pinpointed the location of the West Mata volcano, erupting 4,000 feet below the surface. West Mata is a submarine volcano located 120 miles southwest of the Samoas. The volcano is currently the deepest erupting submarine volcano in the ocean, and the first to ever be filmed erupting.

At subduction zones the oceanic crust on one tectonic plate slides beneath another, producing abundant volcanism and contributing heat, gases and mineral-laden fluids to ocean waters. Scientists have long studied the impact of subduction zones on geological and geochemical cycles. To puzzle out how subduction zones form and evolve they study inactive contemporary marine volcanos that do not produce boninite and they collect and study boninite lavas collected on land and examine cores collected from the deep sea.

"West Mata lies above the subducting Pacific plate and is part of the rapidly expanding Lau Basin, which is bounded by Samoa, Tonga and Fiji. The large bend at the northern end of the Tonga trench produces a tear in the Pacific plate and creates unusual lavas that usually only form at very young subduction zones." Riesing said.

Conditions are right for boninite to form, there’s lots of seawater released from subducting rock that mixes into relatively shallow mantle that has previously melted, causing the mantle to remelt at high temperatures. Boninite lavas are believed to be among the hottest from volcanoes that erupt on Earth.

"What makes this exciting is how uncommon these eruptions of boninite are, both now and in the past. Locked within the boninite is critical information about the rates and magnitudes of subduction-zone magmatism and global geochemical cycles." Rubin said.

The scientists writing in Nature Geoscience think the release of gaseous water, carbon dioxide and sulfur dioxide from the slab is the reason the eruption was so explosive. No one realized such energetic eruptions happened so deep, Resing says. Streams of red and gold lava 35 feet long shot through the water and lava-skinned bubbles some three feet across emerged.

West Mata, which the scientists estimate has been erupting for at least three years, and eight other elongated volcanoes that overlap each other in the northeast Lau Basin sit within one of the most magmatically active areas on Earth, Resing says.

"Observing the eruption in real time was a rare and special opportunity because we know so little about how submarine volcanic activity behaves. This is one of only a handful of glimpses of the process we’ve had to date and is the first time we’ve actually observed natural submarine earthlight from the glowing magma." Embley said.

Source: www.enn.com

Future Migrations in an Environmentally Uncertain World

There are several major forces at play in today's world. Two forces involved with the migrations of people include globalization and mass exodus from the countryside to cities. Another major force, climate change, is playing an ever greater role, affecting societies with extreme droughts, floods, and other dangers. How will future migrations be affected by this force? A new report by a team of experts including Prof. David Thomas and Prof. Stefan Dercon of Oxford University believes that the challenges associated with migrations and environmental change are underestimated. The report concludes that many will emigrate from environmentally vulnerable places, but some may be trapped, and others may actually move closer to the danger.


The report states that migration can have an impact in helping communities adapt to ever more dangerous environment. For policy makers, this may be critical in order to avoid humanitarian disasters in some the hardest hit places like the deserts of Somalia and the flood plains of Bangladesh. Other vulnerable places include low-lying coastal areas which will be impacted by sea-level rise. The authors believe that of all future migrations, 75 percent will be internal, creating burdens not just for national and international authorities, but for municipalities as well.

According to the authors, millions in poorer countries will be unable to move due to costs. As the changing environment affects their livelihoods, they will have less money to spend on moving, especially over long distances. For migrants to more favorable environments, gainful employment may lead to more remittances to low-income countries, allowing remaining individuals a better quality of life

Many individuals will be moving to cities in the future, with the hope of finding higher-paying employment. However, many cities in the developing world are failing environmentally. Many lack clean drinking water, sanitary plumbing, poor air quality, inadequate housing, and lack of access to proper nutrition. Slum cities like Lagos, Nigeria will continue to rapidly grow throughout the Asia and Africa, despite worsening environmental conditions.

According to Professor David Thomas, "Future migration issues and associations with environmental change are complex: it is not simply a story of 'climate refugees'. Rather, critical concerns include the millions who will be trapped in areas prone to growing environmental risks, especially in low-income countries, and the movement of people towards areas where climate and environmental risks are going to grow in the next 50 years. Low-lying coastal zones, and the rapidly growing cities that they support, particularly in Asia and Africa, are particular issues policy makers should focus on."

The report "Migration and Global Environmental Change" has been published by the UK's Foresight Project.

For more information: http://www.bis.gov.uk/foresight