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  TODAY'S WEATHER Overcast 86°F (30°C) Latitude: 1 deg 14’N Longitude: 94 deg 40’W Wind Direction: n/a Wind Speed: calm Sea State: 1 Swell(s) Height: 3-5 Foot Sea Temperature: 84.2°F (29°C) Barometric Pressure: 1013 MB Visibility: 10-25 Nautical Miles  Breakfast Steak and egg burrito Banana nut bread Waffles and sausage Hash browns and hot cereal Eggs to order Mangos and melon Dry cereal Lunch Beef short ribs Mashed potatoes with gravy Buttermilk bisquits Shrimp bisque Baked beans Salad bar Assorted cookies Dinner Parmesan Wahoo Fettuccine Alfredo Rice pilaf Fresh baked dinner rolls Salad bar Lemon cake a la mode Next Stop, the Galapagos Rift RV Melville sliced through the broad low swells of the equatorial Pacific Ocean today at an average speed of 12.3 knots. At 1900 hours (our local time), we were 72 nautical miles from our final survey site, the Galapagos Rift near 97° 30’W Longitude. Try to estimate when we will arrive there Wednesday morning. I'll give you our exact arrival time in tomorrow’s update. After more than 30 days at sea, some familiar foods have started to run out. The cooks on board RV Melville are doing a great job of keeping us well-fed, healthy and in good spirits, but after such a long time away from home and the comforts of our normal, shore-based lives, we start to miss some of the little things. Here are some of the foods we have run out of: English muffins, salad lettuce, granola cereal and strawberries. BUT, we still have plenty of melons, pineapples and mangoes for breakfast, cabbage for slaw, meats and poultry, and, of course, just about all the fresh fish we could ask for. The wahoo that the “Daves” caught yesterday was our main dish at supper today. It was FANTASTIC! Dan Engelbrecht, the head cook, promises to reveal the recipe, and I’ll post it on the Web site. Today, people took the opportunity to catch up on work and rest and prepared to survey the final area we will study on this expedition. There are several very interesting things about this site. First, very little is known about the mid-ocean ridge in this area. It is called the Galapagos Rift because it is close to the Galapagos Islands. At the Galapagos Rift, the Cocos and Nazca plates are spreading apart at about 6 centimeters per year. That speed is about half as fast as the areas on the East Pacific Rise that we mapped earlier during this expedition. No rock samples have ever been recovered from this area. Mike Perfit confirmed this by combing through every existing petrological data base on ocean floor rocks. Also, until last week, no detailed bathymetric map of the area existed, so we had no good idea about the structure of the ridge axis at this site. We collected multibeam data on one survey line last week when we were headed toward the Galapagos Islands. We plan to collect additional data early tomorrow morning. You can see a 3-D perspective of the bathymetry data that we collected last week in today's slide show. The area where we believe the most volcanic activity takes place lies in a 4.5- kilometer-wide rift valley. The shape of the ridge axis is different from that at the crest of the East Pacific Rise at 9-10°N, 3° 20'N or 1° 45'N, which we surveyed earlier during this expedition. Data from the Autonomous Hydrophone Array, which Maya Tolstoy, Julia Getsiv and Chris Fox, our NOAA shore-based collaborator have been analyzing, indicate that that between August 31, 1998, and September 12, 1998, 335 seismic events occurred in the Galapagos Rift valley near 97° 30’W. Most of the events happened in the first few days, and it appears that the epicenters of the seismic events “migrated” along the rift valley as time passed. That indicates that magma rose from the mantle in a long thin channel called a dike, which moved up and away (or “propagated”) from the original source of the magma. Did the dike reach the seafloor and erupt there? That’s what we’re going to try to find out over the next nine days. Starting tomorrow morning, we have planned DSL-120 surveys of the entire floor of the rift valley for about 25 nautical miles along the ridge axis. Based on our previous experiences during this expedition, this will take us about 2.5 days. We can’t wait to discover what this part of the mid-ocean ridge axis looks like and to find young lava flows that would be evidence that a seafloor eruption took place in 1998.
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Woods
Hole Oceanographic Institution
