NOAA Teacher at Sea
Aboard NOAA Ship Fairweather
April 29 – May 13, 2018
Mission: Southeast Alaska Hydrographic Survey
Geographic Area of Cruise: Southeast Alaska
Date: May 6, 2018
Weather from the Bridge
Latitude: 57 43.3 N
Longitude: 133 43.3
Sea Wave Height: 0
Wind Speed: 2 knots
Wind Direction: 202
Visibility: 8 Nautical Mines
Air Temperature: 14 C
Sky: High Cirrus Clouds
Science and Technology Log
When I first learned that I would be on NOAA Ship Fairweather, one of the possible sites, I was told, was a survey including a mud volcano. I did not know anything about mud volcanoes. I knew about ice volcanoes on moons in our solar system, but not about mud volcanoes. NOAA Ship Fairweather found evidence of the methane seeps coming from mud volcanoes, while surveying the Queen Charlotte fault last season. A seep is where gases from below the surface comes out. The area surveyed the first week I was on the ship was just north of the seeps. I wanted to know more so I could share this information. Here is a little background.
In 2015 geologists found a 700 foot gas plume and a couple other active mud cones along the Queen Charlotte – Fairweather fault. Although this fault is not in a highly populated area, it is very active. In the area where the geologists were surveying, liquid natural gas plants and a busy port were close by. They already knew of earthquakes along the fault and that an earthquake in the area today could cause a landslide and generate tsunamis on shore. Older mapping done in the area showed past landslides. But the 2015 survey was looking for the “seeps.”
Scientists first noticed the methane plume coming from the area near the fault. The seep was from an underwater mud volcano. A mud volcano does not have to be made of igneous rock like a traditional volcano. It is formed from gases and mud creating a volcano shaped cone.
Geologists have questioned whether these mud volcanoes may provide a lubricant that could actually lessen the friction on the fault in the area. It would cause the tectonic plates of area to slowly creep along.
NOAA Ship Fairweather also found these seeps during a mapping of the ocean floor along the fault. Below on the right are the plumes of gas rising from the sea floor. Look how high they are rising. Also notice the fan shape on the right. That shows the width of the multibeam sonar at this depth. The colored area on the left are also from NOAA Ship Fairweather’s multibeam sonar with the blues being deeper areas of the seafloor and green to yellow to red getting more shallow. The circled areas show where the seeps were found while the fault line was being mapped.
Life under the sea?
At these seeps, geologists have also found animals that live off of the nutrients of chemosynthetic bacteria. This is bacteria that, instead using the energy of the sun (photosynthesis,) to make energy, they use the materials that come from thermal vents in the ocean floor.
What are other geologic wonders of the area?
First of all there are hot springs! I learned about these hot springs from several of the people on NOAA Ship Fairweather. They report it to be a fun place to visit for a little well deserved time off. There are many hot springs in other areas of Southeast Alaska too. It is a draw for tourists to the area. The hot springs are produced because water seeps down a crack in the Earth’s surface and gets heated, then the super-heated water rises to the surface.
The geology of rock types of the area are also a wonder. It is actually quite complicated, the landscape and seafloor features have been influenced by glaciation, volcanism and plate tectonics, and these geologic influences are still present today. The surveying on NOAA Ship Fairweather is vital to the understanding of the geology that shaped the area. The clues that are beneath the sea help geologist begin to understand southeast Alaska’s dynamic past, and help to predict the geologic future.
After one week on the ship I feel like I just might have to stay! The surveying is really interesting and the views are amazing. When I first arrived I was confused by the passageways and ladder wells on the ship, but now it seems so easy!
I have discovered a few of my favorite places! I love my small room with its own port hole. I really enjoy all of the meals and having time to talk to everyone onboard. People come from all over the US and do a variety of jobs on the ship.
Tomorrow I will have a chance to go off the ship on the small boats. That sounds like great fun!
Did you know?
We just got to a new area with glaciers. The one we could photograph today is Sumdum Glacier. It sounds like a really funny name. It is a Native American word meaning, the sound glaciers make when they are calving, which is what it is called when ice falls off of them.
Some information from:
“Active Mud Volcano Field Discovered off Southeast Alaska.” Eos, 30 Nov. 2015, eos.org/articles/active-mud-volcano-field-discovered-off-southeast-alaska.