Earthscope—An NSF priority that needs congressional support

EarthScope is a proposed multidisciplinary observing system designed to study how the North American continent is deforming in response to ongoing plate tectonics. Arrays of seismometers will move across the contiguous 48 states and Alaska over a 10‐year period to image features that make up the internal structure of the continent and underlying mantle (from “crust to core”). Simultaneously networks of Global Positioning System receivers and strainmeters will measure the rates at which plate tectonic forces are changing the continent, and how geological structures respond to these forces. Space‐based Synthetic Aperture Radar will map changes in the Earth's surface before, during, and after major earthquakes and volcanic eruptions, while a four‐kilometer‐deep observatory bored directly into the San Andreas fault will explore the physical conditions that control earthquake nucleation and fault rupture.