Hold onto Your Hats…Science is Getting Real!

Today we deployed our first OBS (for the second cruise leg)!  This is station WD46.  Most of the instruments being deployed have the setup shown here.  The four orange balls hold glass spheres, which are under vacuum and which contain most of the “guts” of the station.  Two hold $6000 worth of lithium batteries to provide power, the acquisition ball holds the data logger, and the last ball is empty to provide buoyancy. The front of this arrangement is attached to an aluminum arm that also connects to the sensor ball, which houses the seismometer.  The sensor is set away from the rest of the equipment to keep the noise level to a minimum.

Once in the water, a small wire holding the seismometer ball to the arm starts to corrode, detaching within about 24 hours and allowing the sensor to fall to the ocean floor, where it couples with the ground and starts recording earthquakes.

The stations will be deployed for about 15 months.  When ready to retrieve, a signal will be sent to the system that runs a current through a small wire holding the anchor weight to the base.  This causes the wire to rapidly degrade, releasing the weight.  The positive buoyancy of the glass spheres as well as the orange foam block bring the package back to the surface.

So – fingers crossed – we lower the OBS into the ocean.  Here’s hoping all goes as planned.  That’s about $100,000 of equipment heading into the brink!

For this station, the journey to the ocean floor took about 1.5 hours!

Unfortunately, the sensor wasn’t the only thing that went overboard.  Allen, our OBS tech, lost his hard hat over the side.  But the birds were really excited to have something different to look at!  It was last seen heading north toward the horizon.  If found, please return to the R/V Sikuliaq.

– Samantha Hansen (Associate Professor, The University of Alabama)

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