The SIEMBRA array consists of a grid of stations spaced every 15-20 km with denser NE-SW lines that are aligned with the axes of the flat slab portion of the subducting Nazca plate. There are currently 36 broadband (STS and Guralp sensors) and 4 mid-period seismometers (Trillum) deployed as part of this project. Site construction and deployment was conducted from September 2007 to January 2008. Site selection and construction was done mostly on hard rock in order to avoid basin effects caused by loose sediments (click on map below to enlarge).