Day 41 Patgon Masala

I can tell we are getting near the end of this expedition. During the first 3 weeks, people were counting the days to hump-day (the halfway point). After hump-day, they were counting down by days. The past week they’ve been counting by number of meals left, but today they are counting the hours. I am the only person on the ship who will actually be home when we dock the ship. Others will go on to Hawaii, California, Massachusetts, or Washington. Most of the crew members will stay aboard until the ship’s next port of call in Hawaii.

Yesterday we made several passes over Patgon Masala collecting sonar data so Nathan could print an updated map before Jason dived to the center of the caldera. Patgon Masala is an inactive volcano with the largest caldera of any volcano in the Mariana Island system. Good maps make it much easier for the pilot to keep Jason and Medea away from the dangers of encountering unexpected land masses. Everyone in the control van was totally surprised when Jason reached the bottom of the caldera and was surrounded by massive volcanic pillars up to 24 feet high. Matt, the pilot, deftly maneuvered Jason around the pillars. Jason then climbed slowly out of the caldera to the northwest rim. The geologists have excellent collections of rocks and pictures to document the nature of the volcano.

Nathan’s new and improved maps have been used on every coring event and Jason dive during this expedition. Nathan has been sitting in front of a computer about 16 hours a day for 48 days (he started a week before the official start of this expedition). Three types of sonar systems have been used to collect data: the DSL-120 that was towed in deep water behind the ship, and the Sinrad EM300 and Hydrosweep that are mounted to the hull of the ship. Computers on the ship receive the data and convert the sonar time signals to depth. Nathan spends hours removing errors from the data and converts each depth point to a corresponding latitude and longitude. Akel does the initial processing of the DSL-120 data and passes it to Nathan. Nathan uses the software program GMT, Generic Mapping Tools, to actually create the maps.

Nathan made it sound so easy, but I know better. Nathan has always been fascinated by computers. He has been processing sonar data for 6 years. Nathan’s is studying the Malaguana-Gadao Spreading as he works toward his Doctorate so he is especially happy with the new maps of that area. The maps used in the control van are up to 4-feet square and printed right here on the ship.

Jason is back on the surface and being prepared for his deepest dive ever. The geologists want to study a major fault 60 miles to the south of Guam. Jason will drop to 6500 meters (just over 4 miles) and then travel north, up the fault line. The geologists hope to sample uplifted rocks that will help explain the history of magma chamber formation under the volcanic arc.

Jason-I was rated to depths of 6000 meters, but his deepest was to about 5200. Jason-II is capable of 6500 meters and will target that depth tonight on his 44th. dive. Jason uses syntactic foam, valued at ¼ million dollars, for floatation. This is not like Styrofoam (see yesterday’s shrunken heads). It doesn’t compress under extreme pressure.

It’s midnight and Jason has reached 4500 meters. Most of the Jason Team members are crowded into the control van as Jason descends deeper and deeper towards the target. But this day is over and 6500 meters will have to wait until tomorrow.

Science Summary - Day 41, May 2nd

Science Objectives, Day 41:

The forty-first day of the cruise, May 2, we will survey during transit to Patgon-Masala Seamount, and dive on this arc volcano within the large central caldera will take most of the rest of the day to complete a dive up the north wall of the Caldera. Then we will survey across the backarc to the forearc site of the last dive of the cruise.