“I wouldn’t really say that any day at sea is particularly normal,” says Colleen Peters, Lead Marine Technician onboard of R/V Falkor´s MEGATERA expedition, as she talks about the changing nature of oceanic expeditions. “Despite our best efforts, anything can happen and we have to be prepared.”
When it comes to working at sea, plans must be carefully drawn but adjustments are to be expected. “One discovery or event can change the whole experiment. There has been times I have had to redesign a whole experiment at sea, and made a major discovery,” declares Dr. Satish Singh. This point has been particularly true for MEGATERA, as the expedition has followed the tide.
At the center of the action
The Wharton Basin is a tectonic area closely intertwined with the subduction zone next to Sumatra, the expedition’s original objective. What happens at the subduction zone might impact this zone, and vice versa. The 2004 great Indian Ocean earthquake activated faults on the Wharton Basin, for instance.
“The Wharton Basin is the most active intra-plate deformation zone on Earth,” said Dr. Singh, co-leader of the MEGATERA expedition, at the daily scientific meeting. He went on to explain how little is known about its recent seismic behavior: a magnitude 8.6 strike-slip earthquake, thought to be impossible in intra-plate zones, followed by a magnitude 8.2 aftershock.
And there, at the epicenter of that massive aftershock – just outside of Indonesia’s EEZ – is where R/V Falkor conducted a series of bathymetric and seismic reflection surveys over the last two weeks.
Solve the puzzle
Working on the Wharton Basin was not just an educated guess. Dr. Singh has already developed an independent proposal to carry out marine studies in this area, “It was on obvious target for us but we were still very surprised by the discoveries we’ve made,” points out Dr. Singh.
Pull-apart basins at fracture zones, active faults, underwater volcanoes, even a meandering canyon, have all appeared on the screens of the Visual Matrix. “The data we’ve collected so far will allow us to solve the maze-type structure of the 2012 great earthquake ruptures, and provide insight about the deformation in the Wharton Basin,” declares Dr. Singh. It seems the deformation in the Wharton Basin is more widespread than previously recognized, possibly allowing to address a first order generic problem in earth science.
On our way
“It has been like two expeditions in one,” explains Frédérique Leclerc, a tectonic scientist onboard. “Another advantage is that we have become very familiar with the quality of the results yielded by the multibeam echosounder, which is great, so we know that we can be even more ambitious on our Mentawai exploration”.
R/V Falkor is now sailing parallel to Sumatra’s west coast, on its way to the Mentawai gap. This particular area of the subduction zone has not released its stored energy in over 200 years. Scientists suspect an earthquake with a magnitude higher than 8 could originate here.
Well inside Indonesia’s EEZ and with all of the necessary permits at hand, the second half of the MEGATERA expedition has been delineated with greater detail, thanks to the clues provided by the depths of the Wharton Basin.
