The eruptions of "supervolcanoes" on Earth's surface have been blamed for causing mass extinctions, belching large amounts of gases and particles into the atmosphere, and re-paving the ocean floor. The result? Loss of species, increased greenhouse gases in the atmosphere, and changes in ocean circulation. Despite their global impact, the origin and triggering mechanism of these eruptions remain poorly understood. New data collected during a recent Integrated Ocean Drilling Program (IODP) scientific research expedition in the Pacific Ocean may provide clues to unlocking this unsolved mystery in Earth's geologic record.
In fall 2009, an international team of scientists
participating in IODP Expedition 324 "Shatsky Rise Formation,"
drilled five sites in the ocean floor to study the origin of the 145
million-year-old Shatsky Rise volcanic mountain chain. Located approximately 930
miles east of Japan, Shatsky
Rise measures roughly the size of California.
This underwater mountain chain represents one of the largest supervolcanoes in
the world: The top of Shatsky Rise lies about 2 miles below the sea surface,
while its base plunges to nearly 4 miles below the surface. Shatsky Rise is
composed of layers of hardened lava, with individual lava flows that are up to 75
"Seafloor supervolcanoes are characterized by the
eruption of enormous volumes of lava. Studying their formation is critical to
understanding the processes of volcanism and the movement of material from the
Earth's interior to the surface," remarks Dr. William Sager of Texas A&M
University, who led the expedition together
with co-chief scientist Dr. Takashi Sano of Japan's
National Museum of Nature and Science in Tokyo.
About a dozen supervolcanoes exist on Earth – some are found
on land, while others lie at the bottom of the ocean. Those found on the
seafloor often are referred to as "large oceanic plateaus." Current
scientific thinking suggests that these supervolcanoes were caused by eruptions
occurring over a period of a few million years or less – a rapid pace in
geologic time. Each of these supervolcanoes produced several million cubic
kilometers of lava – about 300 times the volume of all the Great Lakes combined
– dwarfing the volume of lava produced by the biggest present-day volcanoes
such as Hawaii.
The IODP Shatsky Rise expedition focused on deciphering the
relationship between supervolcano formation and the boundaries of tectonic
plates, which may prove crucial to understanding what triggers supervolcano
formation. "Shatsky Rise is one of the best places in the world to study
the origin of supervolcanoes," Sager points out.
According to preliminary results, sediments and microfossils
collected during the expedition indicate that parts of the Shatsky Rise plateau
were at one time at or above sea level, and formed an archipelago during the
early Cretaceous period (about 145 million years ago). Shipboard lab studies further
show that much of the lava erupted rapidly, and that Shatsky Rise formed at or
near the equator. As analyses continue in the months and years ahead, data
collected during this expedition may help scientists to resolve the 50 year-old
debate about the origin and nature of large oceanic plateaus.
IODP Expedition 324 "Shatsky Rise Formation" took
place onboard the scientific ocean drilling vessel JOIDES Resolution from Sept.
4 to Nov. 4, 2009. The JOIDES Resolution is one of the primary research vessels
of IODP, an international marine research program dedicated to advancing
scientific understanding of the Earth through drilling, coring and monitoring
Drilling to Study Seafloor Supervolcanoes
April 22, 2010