9315825 Clarke This research will study the upper mantle, including subducting slabs, and the core-mantle boundary by means of a dense linear array of 20 broad-band PASSCAL seismometers installed from Missouri to Massachusetts, a distance of 1736 km. Data from earthquakes recorded by the array will substantially increase resolution of structures such as the core-mantle boundary under the Pacific, slab penetration depths in the Aleutians, Kuril-Kamchatka, Peru-Chile, and Central America, and the details of the upper mantle under North America and the Caribbean. This work should shed significant new insight into details of the earth's convection engine and resultant driving forces of plates and earthquakes. ***
