Expedition 344 summary

Abstract

The Costa Rica Seismogenesis Project (CRISP) was designed to elucidate processes that control nucleation and seismic rupture of large earthquakes at erosional subduction zones. The CRISP study area is located offshore the Osa Peninsula where the incoming Cocos Ridge has lifted the seismogenic zone to within reach of scientific drilling. This area is characterized by low sediment supply, a fast convergence rate, abundant plate interface seismicity, and a change in subducting plate relief along strike. In addition to elucidating processes at erosional convergent margins, this project is complementary to other deep fault drilling projects (e.g., The Nankai Trough Seismogenic Zone Experiment and the Japan Trench Fast Drilling Project). Integrated Ocean Drilling Program (IODP) Expedition 344 is the second expedition of CRISP Program A (IODP Proposal 537A-Full5), a first step toward deep riser drilling through the seismogenic zone. The focus of CRISP Program A is on the shallow lithologic, hydrologic, stress, and thermal conditions that lead to unstable slip in the seismogenic zone. Together with IODP Expedition 334, the first expedition of CRISP Program A, these data provide exciting insights into the nature of seismogenesis and erosive plate boundaries.