Our project will focus on the subduction zone off southern Alaska, which produces large and destructive earthquakes.
Rarely a day goes by without earthquakes shaking the Alaska Peninsula, a string of volcanoes curving off the Alaska mainland into the Pacific. Just off shore, two tectonic plates are converging: The Pacific plate is bending under the North American plate and pushing deep into the Earth. Along this subduction zone, scientists have noticed something unusual. Two adjacent sections that appear almost identical in large-scale characteristics—temperature, angle of subduction, age of the rocks—are exhibiting very different earthquake behaviors over short spans of just tens of kilometers. One section is highly active with small earthquakes; the other is more quiet but has large earthquakes every 50 to 75 years. To get a closer look, Lamont-Doherty Earth Observatory’s research ship, the R/V Marcus G. Langseth, ran seismic surveys to map the ocean floor and the earth beneath it.