New Zealand Quake Cruise 2

Last Ocean Bottom Seismometer recovered! »

by asheehan | posted: February 16th, 2010

Anne on the R/V Revelle with the last OBS retrieved.

Our Ocean Bottom Seismometer (OBS) recoveries off the east coast of New Zealand have been a success, and our last OBS has now been recovered! We have had heavier seas and high winds the past week. Our final OBS count is 29 recovered out of 30 total deployed a year ago. The last one may still turn up some day – maybe it is floating to Australia or Antarctica – who knows? Our science team is in good spirits but we are also very busy preparing our cruise report. In the next few days we need to organize and archive all of the seismic, gravity, magnetics, multibeam, current profiling, and 3.5 kHz sounding data that we collected, describe our data collection process, and summarize initial impressions of the data and results. We are now mapping the seafloor of the Chatham Rise, exploring for seafloor volcanoes and pockmarked bathymetry, and we start our transit back to Wellington tomorrow. Continue reading Last Ocean Bottom Seismometer recovered!

Magnetic Surveying »

by asheehan | posted: February 14th, 2010

Shark bite mark on the magnetometer - note the serrated edge. Sometimes it comes back with a shark tooth embedded in it.

Magnetometer

Earlier this week we performed a magnetics survey off the coast of southwest New Zealand. Our new magnetic data will be used by our New Zealand colleagues to piece together part of the tectonic history of New Zealand.

When molten rocks cool, they freeze in a record of the Earth’s magnetic field. The Earth’s magnetic poles have reversed polarity numerous times in the geologic past, creating a distinct pattern of magnetic anomalies through time. Continue reading Magnetic Surveying

(Tiny) Creatures from the Deep »

by asheehan | posted: February 12th, 2010

The OBS’s spent a year on the seafloor, and during that time became home to or were visited by some small sea creatures. With this post is a collection of photos of some of these small animals that came up with the OBS’s. Most of them have very little pigment – can you guess why? Continue reading (Tiny) Creatures from the Deep

Heading east »

by asheehan | posted: February 10th, 2010

Our deck is filling up with recovered OBS's waiting to be sent home.

We have completed our work off the west coast of New Zealand, and are now heading south and east. The count is 20 out of 21 ocean bottom seismometers (OBS) recovered. That is a good recovery rate. Out of the 21: one was not found – no signal (NZ17), one was picked up by fishermen in July (NZ15), two had to be dredged up from the bottom (NZ9 and NZ10), and the remaining 17 came up without incident. We have 9 more OBS’s on the east side to pick up in the next week. Continue reading Heading east

Bioluminescent jellyfish »

by asheehan | posted: February 9th, 2010

The glowing part of this jellyfish is similar to what we saw. Photograph courtesy Martin George/QVMAG.

A few nights ago we saw thousands of bio-luminescent creatures in the water – we think they were jellyfish, but are not sure. They were about 2-3 feet long and tube-shaped, and glowed green. It was an incredible sight. The stern (back of the ship) was where the big show was – thousands of them in a swirling, glowing, greenish trail behind us.

I tried to video it but it came out completely black. If we see them again I will try a long exposure with my regular camera.

(2/13/10 Captain Dave says that the glowing creatures were ctenophores. They are also known as comb jellies. You can find some information about them at http://www.ucmp.berkeley.edu/cnidaria/ctenophora.html and

http://en.wikipedia.org/wiki/Ctenophora)

Continue reading Bioluminescent jellyfish

Persistence pays off »

by asheehan | posted: February 6th, 2010

Our euphoria from the resue of OBS9 was short-lived. The next day was fine, with 3 OBS’s recovered with no problems, and awesome views of the Southern Alps. The following day, however, was trouble. We had the same problem with OBS10 as we did with the formerly stuck OBS9. We could communicate with it, but it did not drop its weight and surface. Continue reading Persistence pays off

The Southern Alps »

by asheehan | posted: February 4th, 2010

The past few days we have been lucky enough to be within sight of the Southern Alps. Beee-yoo-ti-ful. The Southern Alps are a big part of why we are on this research cruise – not just to look at them with our eyes, but to look beneath them with seismic waves.

A nice intro to New Zealand geology can be found at http://data.gns.cri.nz/geoatlas/text.jsp

A description of the Southern Alps and Alpine fault can be found at

http://www.otago.ac.nz/geology/research/structural_geology/alpinefault/index.html

Some animations of New Zealand geology through time can be found at
http://www.gns.cri.nz/what/earthhist/nz_origins/paleo/index.html
Check it out!

View of the Southern Alps and Franz Josef glacier from OBS14. Photo by Peter Molnar.

Follow the link for more photos. Continue reading The Southern Alps

OBS rescue (with video) »

by asheehan | posted: February 2nd, 2010

Yesterday we returned to OBS9 and rescued it. It is amazing that it worked. We could communicate clearly with OBS9, but it never dropped its weight and surfaced. We were not sure why – maybe stuck in the mud, or having a net draped over it, or simply the burn commands to release the weight not working. We tried for about 6 hours to send commands to release the weights, and finally moved on to retrieve OBS14 with the plan to return to rescue OBS9 in daylight.

OBS9 was at 1335 m water depth. By acoustic sounding we knew where it was on the bottom within a few meters. The ResTech (resident research technician) Meghan devised a plan to drop a cable with grappling hook and dredge basket at the site of the OBS, forming a circle of wire around the OBS of about 200 m radius, and then closing the loop and hopefully jarring the OBS loose from whatever held it down. Continue reading OBS rescue (with video)

Life at Sea »

by asheehan | posted: February 1st, 2010

My cabin

Life at sea is very simple – no commuting, no cooking, no cell phones. Three delicious meals per day are prepared by the cooks Mark and Ahsha, and a large range of both healthy and not-so-healthy snacks are available all the time (including a refrigerator full of assorted ice cream bars – the New Zealand ones go fast!). To balance all of the eating, exercise equipment is tucked away in several places on board. There is a treadmill, rowing machine, stair stepper, exercise bike, and a small weight room. When the weather is fine, walking on the decks can be good exercise (the motion of the ship can turn a regular walk into a core strengthening and stability exercise). Table tennis is popular, also made challenging by the ship’s motion. There is a small lounge with an assortment of DVD’s for watching, and a small library with well worn paperbacks left by former crew and science teams.

Continue reading Life at Sea

Ocean bottom seismometer retrieval video »

by asheehan | posted: January 30th, 2010

Here is my first attempt at using iMovie to make a video and upload it to YouTube. It is of retrieving OBS #NZ8

[youtube]http://www.youtube.com/watch?v=5I7cb8s4CMQ[/youtube]