Earth Observatory Blog
Farewell from the MIRAGE
It has been almost a month since we left the port of Colombo to make our way to the Wharton Basin, a place so remote that I can count on one hand the number of container ships and fishing boats I saw during our three weeks there.
In that time, we surveyed 90,000 square kilometres (km2) of seafloor, an area roughly the size of Ireland, acquiring bathymetry, gravity and magnetic data, sub-bottom profiles, and several dozen metres of sediments taken during two marathon coring operations.
The last time a research vessel was in the Wharton Basin, during the MEGA-TERA cruise of 2015, 7,500 km2of bathymetry was acquired, plus another 950 kilometres (km) of high-resolution seismic reflection data. By any measure, the MIRAGE has added enormously to the knowledge base, ensuring that the crew of MIRAGE II will be well prepared when they return in 2017 to focus on seismic reflection.
As expected, we found numerous faults running north and south, including at least one that no one had ever seen. We also mapped a twisting canyon carved by a seafloor river, whose source is probably the Irrawaddy in Myanmar almost 2,000 km to the north. And then, of course, there was our beloved seamount, a beautiful feature that measures 30 km across, rises 1,800 metres above the seafloor, and is cracked in half by a strike-slip fault running east and west.
For the most part, it was a congenial, no-drama cruise, in which students and scientists enjoyed each other’s company, working and relaxing together like a group of old friends. Which is why when the colleagues we had picked up in Sabang, Indonesia, almost a month ago were dropped off the other day (along with our core samples), those who remained on board were sad to see them leave. Our voyage, we realised, would soon be coming to an end.
Sabang had other plans. Perhaps sensing our melancholy mood, the scrupulous custom officials there carefully checked each and every passport of the ship’s passengers and crew, scanning each document and emailing it to Jakarta for approval, one by one. With more than 70 passports to process, Sabang’s small customs office was overwhelmed, which is why our stay in the harbour (we were not permitted to go ashore) lasted 36 hours instead of two or three. As a result, I believe I can safely say that I have spent more time in Sabang than any other place I’ve never been.
Some of us, including yours truly, will miss our flights home due to this delay, as well as the two hours we spent dead in the water on the way to Colombo—the crew had to clear Styrofoam and a tangle of rope from the gondola unit housing the echosounder and sub-bottom profiler. And we have been told to expect more delays once we get into port.
All of this has been frustrating, to be sure, but the delays have given me a bit of extra time to reflect on the nature of our work in the Wharton Basin, and the task of geophysicists in general.
My conclusion is that I honestly don’t know how scientists keep their perspective. After all, we are small and our time on this earth is fleeting. In contrast, the plates below our feet are unimaginably enormous and old, moving imperceptibly. Except, of course, when they remind us of their presence by erupting as volcanoes, shaking the ground as earthquakes, and sending tsunamis crashing to shore.
If our perspective was as long as that of a tectonic plate, such events would barely command our attention, and we would probably not bother to debate topics such as where the diffused plate boundary in the middle of the Indo-Australian plate will ultimately manifest itself as a clearly identifiable line.
But debate we do, speaking of these seemingly stationary plates in terms of their velocity, even though sensitive instruments are required to measure their movements. Young lithosphere, as in seafloor made within the last 25 million years, is described as light and buoyant, as if it were a fluffy meringue, albeit a meringue that has difficulty subducting under places like Sumatra and causing events like the deadly magnitude-9.2 earthquake of 2004.
That’s probably why scientists try to make sense of it all. Yes, as a group, scientists are almost genetically predisposed to look for answers to complicated questions, for their own sake. But the answers to questions about what’s happening right this second in the Wharton Basin have a human impact, and that’s what makes the enterprise of science more than a mere academic exercise. As with the experience of being on a ship like the Marion Dufresne for an entire month, in the end, it’s really about people.
To read all about the MIRAGE expedition, please check the EOS blog archives for the month of July, and spread the word using #MIRAGEcruise.
All photographs are taken by Ben Marks, unless otherwise stated.