Fig. 2. The Seismogenic Zone Experiment seeks to define the conditions and materials that control earthquake cycles and processes on subduction zone megathrusts. In addition to the observational strategies depicted in the figure, SEIZE investigators will conduct laboratory experiments and formulate testable quantitative models of how the subduction cycle works, including the complex interactions among the various chemical and mechanical processes. Testing these models through deep riser drilling into, and monitoring of, the seismogenic zone is a prime goal of SEIZE.