Hikurangi subduction zone expedition #375 – blog 5
In March 2018, JOIDES Resolution, a large scientific research vessel, headed out to sea to research the Hikurangi subduction zone on expedition #375. This article is the fifth blog from Aliki Weststrate, IODP (International Ocean Discovery Program) Outreach Educator. This is her account of a voyage full of excitement, challenges and science!
Bad weather hits expedition #375
This week was dominated by weather. We heard on Tuesday that big swells were heading our way due to a cold southerly screaming up the country. The captain was out in this same location in November 2017 on expedition #372 when they were caught out with 10 m waves – so big they hit the bridge.
Stormy seas on board JOIDES Resolution
The swell started to build as JOIDES Resolution left the Tūranganui Knoll seamount, 90 km east of Gisborne. We sailed slowly into strong winds for 18 hours to reach the calmer Bay of Plenty to wait out the storm.
To avoid this kind of weather again and look after this relatively old ship (JOIDES Resolution was built in 1985), he chose to head north to shelter near Tauranga in the Bay of Plenty, well away from the southerly and its worst effects. On the daily ship reports to staff, they call this WOW – waiting on weather.
The transit back to the research site took longer than expected because we encountered gale headwinds and big seas.
It was a pretty sleepless night for most of us, with the waves and anchor slamming into the bow near our cabins.
Aliki Weststrate
Sea sickness tablets
On board JOIDES Resolution, the doctor would usually prescribe you sea sickness pills, but the transit happened while he was asleep, so he left them out for the night shift crew in case we needed them. They make you a bit drowsy but work well.
We lost 3 days out of our schedule because of the storm. The two Co-chief Scientists say this is to be expected on a 2-month voyage and that we are actually still tracking well for achieving all our science objectives at the Hikurangi subduction zone.
There are so many things out of your control on a science expedition in the open ocean. It means everyone has to be very good at problem solving and adapting.
What does the crew do when there is no core to analyse?
The storm meant we could not drill and collect new core samples. This gave scientists some much-needed downtime. They had been working long hours at our previous site analysing the core from the seamount. Working 12-hour shifts with no weekends off gets tiring by week 5! Apart from writing their site reports and doing presentations on this, they spent the time playing table tennis, going to the gym, eating and watching movies.
Table tennis on board JOIDES Resolution
After people’s shifts, they relax by playing table tennis (here we have England versus Germany!), playing board games, going to the gym, playing music and watching movies. It is hard to play table tennis on conference tables while the ship is rolling!
The sum is greater than its parts
Each science group produces a report and presentation for every site. The six science teams on this expedition studying different aspects of the Hikurangi subduction zone focus on:
geochemistry
structural geology
sedimentology
physical properties
palaeomagnetics
palaeontology.
Each team has 2–4 people in it, and they are all specialists in their field of Earth science. The team leaders have usually sailed before and are very experienced in their area, but the teams also include early-career geologists doing a PhD. It’s a great learning experience for them. The wonderful thing about this multidisciplinary team is that they all bring different perspectives and knowledge.
As a team, they are putting the various parts of the puzzle together, which they could not do in isolation.
Aliki Weststrate
A scientist writing a scientific report
A geochemist from Germany tries to finish his site report and make a PowerPoint presentation to show the science crew the geochemistry of the seamount site.
This multidisciplinary approach is the best way to solve the challenging questions we have about slow slip earthquakes, large earthquakes and tsunamis at the Hikurangi subduction zone.
Other JOIDES Resolution expeditions studying climate change also have a team of oceanographers and sometimes marine biologists on board as well.
The calm after the storm
We transited back to the East Coast quite quickly on Friday to arrive at our third site, U1519.
Seafloor map showing site U1519, close to Gisborne
This seafloor maps shows expedition #375’s third site, U1519, which is further west than the previous site. It sits above the sedimentary basin on what we call the upper plate boundary.
At this site, we are installing New Zealand’s second sub-seafloor observatory, and because it is simpler than the first, it should only take us a week to deploy it 280 m under the seafloor.
Blog 3 details how the first observatory under the seafloor was installed.
The geology of site U1519
The location of our second and less-complex observatory is 33 km from the coast and only 5 km above a known slow slip zone in the harder rock mass of the Hikurangi subduction zone. This is an area called the upper plate or upper slope and is mid-slope on a sedimentary basin. It sits quite close to the shallow continental shelf that is attached to the east coast. At 1,003 metres, the water is not so deep here as our previous sites.
My next blog will be focused on attaching the pressure and temperature sensors to the rope that will be lowered into the borehole and then sealing it shut.
Related content
This article gives some background to the scientific research vessel JOIDES Resolution.
Read Aliki’s other blog articles here.
Activity idea
Your students will learn how the tectonic plates covering the Earth fit together like puzzle pieces in this activity.
Useful links
Watch as observatory specialist Patrick Fulton uses ancient mariner’s techniques combined with high-tech equipment in our observatories.
Watch an animation on how we installed the first observatory, Te Matakite.
In this YouTube clip, scientists on JOIDES Resolution talk about their research, what they are looking for and how they will examine the core samples when they return home.
What are the expedition #375 objectives? This YouTube clip explains them.
Watch this YouTube clip about JOIDES Resolution and its research.
Learn more about the international science vessel JOIDES Resolution and more about expedition #375.
Watch the expedition #375 trailer – what is our mission at the Hikurangi subduction zone?
Acknowledgement
This article was written by staff at GNS Science working as part of the ANZIC IODP Consortium.
GNS Science
GNS Science, Te Pū Ao, is New Zealand’s leading provider of Earth, geoscience and isotope research and consultancy services. Its purpose is to understand natural Earth system processes and resources and to translate these into economic, environmental and social benefits.
