ABSTRACT
EarthScope is a scientific and infrastructure initiative designed to address fundamental questions about the evolution of continents and provide essential data needed for a clearer understanding of the processes responsible for earthquakes and volcanic eruptions.

EarthScope includes a set of integrated observing systems that will capitalize on recent developments in sensor technology and communications to provide Earth scientists with synoptic and high-resolution data derived from a variety of geophysical sensors. An array of 400 broadband seismometers will spend up to 15 years crossing the contiguous 48 states and Alaska to image features that make up the internal structure of the continent and underlying mantle. Additional instruments will be available for high resolution imaging of geological targets of special interest. A network of continuously recording Global Positioning System (GPS) receivers and sensitive borehole strainmeters will be installed along the western plate boundary.  The sensors will measure how western North America is deforming, what motions occur along faults, how earthquakes start, and how magma flows beneath active volcanoes. A four-kilometer deep observatory bored directly into the San Andreas fault will provide the first opportunity to observe directly the conditions under which earthquakes occur, to collect fault rocks and fluids for laboratory study, and to monitor continuously an active fault zone at depth. All data from EarthScope will be openly available in real-time to maximize participation from the scientific community and to provide on-going educational outreach to students and the public.

EarthScope’s sensors will revolutionize observational geophysics in terms of the quantity, quality and spatial extent of the data they provide. Turning these data into exciting scientific discovery will require new modes of experimentation and interdisciplinary cooperation from the Earth Science community. IRIS and PASSCAL have played an important role in helping to stimulate the development of USArray and move EarthScope forward as a community initiative. With strong prospects for funding this year, the time is right for bold new ideas in how to maximize the use of these powerful new resources in the Earth scientist’s toolkit.