Young Pacific ORCA sets sail!

R/V Kilo Moana – Pacific Array OBS deployment #1

Welcome to the Pacific ORCA (Pacific OBS Research into Convecting Asthenosphere) deployment blog! We hope you’ll keep up with our progress as we head out into the Pacific, chasing new horizons (both literal and scientific!)

Our good ship Kilo Moana departed San Diego on Saturday morning, 4/7/18 at 0800, setting course SSE [track us here]. All told we have 36 souls aboard, including a science party of 14 that comprises faculty, postdoctoral researchers and graduate students from 9 institutions (spanning 3 continents), as well as a couple of techs from the Scripps Institute of Oceanography. It’s a fantastic and diverse group of scientists, united by an eagerness to learn more about the solid Earth. Which is a bit ironic, considering that this is the first time most of us have ever seen this much water!

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The good ship R/V Kilo Moana. Home for the next month. The yellow things on the back are our OBS instruments, all squared away.
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All aboard!

We’re supported, sustained, and kept shipshape by a phenomenal crew of experienced sailors that run the Kilo Moana, a 186’ twin hull research vessel (R/V) owned by the U.S. Navy and operated by the University of Hawaii Marine Center. They’re on a year-round research schedule, spending more than 230 days at sea doing science this year alone. These folks’ maritime expertise allows us to do our research, and we’re very grateful to them for getting us where we need to go and showing us landlubbers the ropes (sometimes literally; we had a knot-tying tutorial yesterday).

The purpose of our cruise is to deploy 30 ocean-bottom seismometers (OBS) right in the middle of the Pacific Ocean, with the goal of producing 3-D images of the oceanic tectonic plates… and whatever lies below them. Our little instruments (they’re actually more than a meter across) will sit on the ocean floor, ~4500 m beneath the waves, for approximately 15 months, recording earthquakes around the world. When we return to retrieve them next year – assuming they all come back to us! – they’ll hold seismic data in their memory banks that could change the way in which we understand the oceanic plates. Which is pretty significant, considering that these plates make up about 70% of our planet’s surface.

In addition to the host of specific science questions we hope to directly address with this data set, this experiment is one part of the U.S. contribution to an international “Pacific array of arrays”. This vision, pioneered by Hitoshi Kawakatsu, involves several clusters of seismic instruments spread over the Pacific ocean floor by collaborating researchers from Japan, Taiwan, Australia, New Zealand, and South Korea, and hopefully more in the near future. The Pacific ocean is quite large (understatement alert), and so for a scientific community that thinks on a planetary scale, we must coordinate to pool international resources and share data. By combining our efforts across numerous individual experiments, the geosciences community is poised to break new ground (What? Everyone loves puns.) in our understanding of the solid Earth.

Over the course of this blog, we’ll describe in detail what we’re doing to stay busy, how the instruments work, what we’re hoping to see, how we deploy them, and what life on the ship is like.

Stay tuned!

Zach Eilon, on behalf of the Pacific ORCA team
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Our OBS bodies (minus the actual seismometer, stowed separately). You can see why this model is affectionately known as “SpongeBob”.
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