Understanding offshore faults Aaron Micallef writes: Offshore faults are important sources of earthquakes and associated tsunamis. To investigate the occurrence of offshore faults, marine geologists look for two kinds of evidence. The first is topographic, such as a linear escarpment (an elongated change in slope gradient) or abrupt changes in the form and orientation of …

Sampling sediment at Coronado Canyon On this expedition we are exploring the offshore extensions of tectonic faults that cross the northern Baja California peninsula or run offshore parallel to the Baja peninsula and coastline of Southern California. These faults are believed to be part of a system of faults that extends northward, crossing the U.S.-Mexico …

Rich biodiversity at Pescadero Basin Yossellin Tapia De la O writes: Today we returned to Pescadero Basin, which is, undoubtedly, an exceptional place that we had to revisit with its active chimneys and mounds, and the rich biodiversity they nourish. During the survey with the ROV, we were often very close to colonies of Riftia or Oasisia, and …

Returning to hydrothermal vents at Pescadero Basin Bob Vrijenhoek writes: Today we finished the last dive of Leg 6. It was a productive day and it started somewhat auspiciously. The wind was blowing close to 20 knots at 6:00 a.m., just before launch time. Would it increase or decrease during the next half hour? Luckily for …

Vesicomyid clams Elena Krylova writes: Vesicomyid clams are conspicuous and consistent members of hydrothermal vent and hydrocarbon seep communities worldwide. Nevertheless, they remain one of the most poorly understood bivalves. Two vesicomyid species were described from the Gulf of California by the American mollusc expert William Healey Dall more than 100 years ago. Those clams …

Female squid, octopuses, and cuttlefish end life with a bang. Usually, these soft-bodied cephalopods die after a single, end-of-life reproductive blaze of glory. But scientists have recently learned that one deep-red, foot-long cephalopod breaks this deadly pattern.

Vent communities at Alarcón Rise and Glitter Lake Kris Walz writes: Today is Earth Day, a perfect day to be afloat on the surface of the ocean, exploring the deep-sea communities thousands of meters below. Over 70 percent of Earth’s surface is covered by oceans making the seafloor one of the world’s largest habitats. Covering …

Hydrothermal vents at Alarcón Rise Corinna Breusing writes: 6 a.m.: Time to get up to watch the launch of the ROV Doc Ricketts in 30 minutes. It will take about 1.5 hours for the ROV to reach the seafloor and allow us to take another glimpse at the mysterious world of deep-sea vents in the Gulf of California. …

Plumes of black smoke Shannon Johnson: Today was an amazing day of exploration and discovery at one of the most exciting natural habitats of the deep sea—black smokers. We explored enormous hydrothermal vent chimneys, majestic columns eight to 37 meters tall, emitting voluminous plumes of black smoke. The chimneys were covered with dense thickets of …

Mounds and chimneys in Pescadero Basin Greg Rouse writes: Today we returned to Pescadero Basin to continue exploring the active mounds and chimneys in the area at 3,700 meters depth and to document and collect various animals. These biological collections are important as they will allow us to compare vent systems further south on the …

Riftia, the Reigning Queen Verena Tunnicliffe writes: Nestled in a very deep valley in the Gulf of California lies what we’ve called the “Mermaid Castle” where tubeworms and anemones sway in the wafting warm waters. Well, it did look a bit like a fantasy land to us! So close to land, the seafloor slumps to …

Lines all clear Shana Gofffredi writes: At 7:03 AM, we set sail on a cool overcast day from La Paz, Mexico, aboard the R/V Western Flyer. The 10 scientists onboard all specialize in various aspects of deep-sea biology, ecology, evolution, taxonomy, and microbiology. The main goal for the expedition is to explore newly discovered deep-sea hydrothermal …

Wrapping up the Volcanoes and Seamounts leg Dave Clague writes: This has been a great cruise with almost all of our initial goals met and some new discoveries added on top. As Rob Zierenberg noted yesterday, numbers sometimes tell a story and here are some more from this cruise. We collected 191 lava samples, 14 samples …

Collecting hydrothermal fluid Rob Zierenberg writes: The number for today seems to be 33—the current wind speed in knots. Waves are pounding into the ship and we cannot launch the ROV in this weather. Everyone was really looking forward to today’s dive, which was in Pescadero Basin, the next spreading segment north of the Alarcón Rise. …

Understanding the evolution of Alarcón Rise Dave Clague writes: As previously mentioned, the Alarcón Rise is the northernmost segment of the East Pacific Rise spreading center. The Alarcón Rise is roughly 50 kilometers long. It is the axis along which new ocean crust is forming as a rocky ridge, compared to the short spreading segments …

Traveling back in time Julie Bowles writes: Today was like traveling back in time! Our goal was to establish an approximate eruptive history at this location, so we started our dive about three kilometers to the west of the active Alarcón Rise axis. Flows out here are generally tens of thousands of years older than what is …

Hydrothermal chimneys, basaltic pillows, and lava flows Jenny Paduan writes: Today’s dive was, as the Wisconsinites on board (Julie Bowles, Knute Brekke, and Patrick Mitts) would say, a smorgasbord! There were new and very impressive hydrothermal chimneys, mounds of lovely elongate basaltic pillows, and a vast flood of a relatively young, jumbled sheet-like lava flow, which …

Tamayo transform fault Julie Bowles writes:Today’s dive targeted the southernmost end of the Alarcón Rise, where it transitions from oceanic spreading center to what is called a transform fault. Whereas the volcanically-active spreading center is where new oceanic crust is formed and two tectonic plates move away from one another, a transform fault is not …

Meyibó hydrothermal vent field Ronald Spelz writes: Today’s dive on the Alarcón Rise started in a newly discovered active hydrothermal field, a vent through which hot fluids emerge from the seafloor. The tall chimney edifices, along with their peculiar deep-sea inhabitants, and their jetting hot fluids, literally gave us a “very warm” welcome. We decided …

High-silica lava flows at Alarcón Rise Brian Dreyer writes: A primary goal of today’s dive was to explore the extent of high-silica lava flows at Alarcón Rise. These flows are common on land volcanoes but rare at oceanic spreading centers—sites where two tectonic plates move away from one another. Most spreading centers erupt low-silica lava …