John A. Orcutt

Learn More
Seismic data from the ultrafast-spreading (150 to 162 millimeters per year) southern East Pacific Rise show that the rise axis is underlain by a thin (less than 200 meters thick) extrusive volcanic layer (seismic layer 2A) that thickens rapidly off axis. Also beneath the rise axis is a narrow (less than 1 kilometer wide) melt sill that is in some places(More)
Spreading segments of the Mid-Atlantic Ridge show negative bull's-eye anomalies in the mantle Bouguer gravity field. Seismic refraction results from 33 degrees S indicate that these anomalies can be accounted for by variations in crustal thickness along a segment. The crust is thicker in the center and thinner at the end of the spreading segment, and these(More)
Defining the mantle structure that lies beneath hot spots is important for revealing their depth of origin. Three-dimensional images of shear-wave velocity beneath the Hawaiian Islands, obtained from a network of sea-floor and land seismometers, show an upper-mantle low-velocity anomaly that is elongated in the direction of the island chain and surrounded(More)
17. MBAs are calculated by subtracting from the free-air anomaly the gravitational attraction of sea-floor topography and Moho relief that is assumed to parallel the sea floor (except that the Moho does not shoal beneath seamounts). If crust has a constant density and thickness and the mantle density is constant, then the MBA will be constant. The large,(More)
The Mantle Electromagnetic and Tomography (MELT) Experiment was designed to distinguish between competing models of magma generation beneath mid-ocean ridges. Seismological observations demonstrate that basaltic melt is present beneath the East Pacific Rise spreading center in a broad region several hundred kilometers across and extending to depths greater(More)
e-Science in the 21st Century " As research on so many fronts is becoming increasingly dependent on computation, all science, it seems, is becoming computer science, " heralded The New York Times in an article in 2001. [Johnson] The United Kingdom Research Councils define e-science as large-scale science carried out through distributed global collaborations(More)
The determination of melt distribution in the crust and the nature of the crust-mantle boundary (the 'Moho') is fundamental to the understanding of crustal accretion processes at oceanic spreading centres. Upper-crustal magma chambers have been imaged beneath fast- and intermediate-spreading centres but it has been difficult to image structures beneath(More)
Figure 1. Locations and names of three ocean-bottom seis-mographs (OBS) used to locate events and NOAA-PMEL's bottom-pressure recorder (BPR). All located earthquakes are shown as green dots. Purple star indicates location of water-column anomaly as recorded during OBS deployments. Lower right figure shows outline of 1998 flow (Em-bley et al., 1999) compared(More)
The Ocean Observatories Initiative (OOI) will implement ocean sensor networks covering a diversity of oceanic environments, ranging from the coastal to the deep ocean. Construction will begin in Fall 2009, with deployment phased over five years. The integrating feature of the OOI is a comprehensive Cyberinfrastructure (CI), whose design is based on(More)