The NSAF expedition explores the region, its history, and its biologic diversity along the fault.

The NSAF expedition explores the region, its history, and its biologic diversity along the fault. Click image for larger view and image credit.

View a slideshow of images from the expedition.

slideshow icon View a slideshow of images from the expedition.

Cradle of the Earthquake: Exploring the Underwater San Andreas Fault 2010

September 10 – October 3, 2010

slideshow icon Click here to view the San Andreas Fault 2010 Mission Trailer.

It has been over a century since the Great 1906 Earthquake that nearly destroyed San Francisco. The Northern San Andreas Fault (NSAF) ruptured nearly a quarter of a mile, from the Mendocino Triple Junction to San Juan Bautista, passing only one mile offshore from the city. For much of its length, this great plate boundary fault between the Pacific and North American plates lies offshore.

The investigation of the submarine Northern San Andreas has so far been very remote. Fundamental unknowns, such as the repeat time of great earthquakes and the patterns in which they occur, remain unanswered because we rarely have a long enough earthquake record. In the case of the NSAF, this is in part because much of the fault is underwater.

In addition to its earthquake history, the ecosystem of the offshore San Andreas Fault is equally unexplored, and may possess unique and exceptional biodiversity. From prairies to rainforests, in terrestrial ecosystems, disturbance plays a crucial role in the maintenance of high diversity hotspots. In the ocean, however, the role of natural disturbance in the creation and maintenance of biologically diverse hotspots is largely unknown.

Over one hundred years after the devastating Great Earthquake, our expedition explores the NSAF, the history of past earthquakes, and the intertwined relationships between large earthquakes and biologic diversity along this, the fastest moving fault in western North America. Our multidisciplinary exploration will help us to understand how tectonic history relates to biodiversity hotspots, and to predict the response these biologically active areas have to future disturbances. Our expedition combines cutting-edge technology with the use of an innovative, fuel-efficient vessel to explore the past and predict the future of this unexplored geobiologic system.


Updates & Logs
Click images or links below for detailed mission logs and updates.

Mission Summary Mission Summary During this exploration, we completed the first comprehensive high-resolution multibeam sonar and seismic reflection survey of the NSAF. Data from these two complementary geophysical surveys will provide an unprecedented 3D visualization of the fault system.

September 29 September 29 The scientists involved in exploring the Northern San Andreas Fault are using a variety of sonic and optical imaging systems to visualize geology, geohabitats, and biological communities associated with the fault.

September 27 September 27 Even though the AUV is working autonomously, sometimes we want to communicate with it in order to follow its progress in accomplishing its dive plan and in some cases to ask to change its mission during a dive.

September 25 September 25 We’re now collecting about 50 “seismic-reflection” profiles across the Northern San Andreas Fault to image the subsurface structure of the fault zone.

September 23 September 23 Living on a sailboat for anywhere from 2 to 6 days between port calls is an experiment and experience in itself.

September 21 September 21 By using sonar, we are able to both determine the depth of the seafloor and obtain information about what type of sediments or hard bottoms are below.

September 20 September 20 With clear skies and winds from the northwest, today we were finally able to turn off the engines and run multibeam survey lines by sail.

September 18

September 18 There is a very small window for conducting research cruises off the Northern California coast. Even in the weather window, the seas can be unpredictable.

September 17 September 17 The first leg of this expedition has been dedicated to mapping the San Andreas Fault and surrounding seafloor via multibeam sonar.

September 14 September 14 After a flurry of activity with mobilization, we're finally off on our multibeam survey of the northern San Andreas.


You can access the Ocean Explorer San Andreas Fault 2010 News Feed here: NOAA RSS 2.0 Feed