PBO STRAINMETER NETWORK: GEOPHYSICAL AND GEOLOGIC RESOURCES FOR FURTHER UNDERSTANDING OF THE WESTERN NORTH AMERICAN PLATE

Upon completion of the Plate Boundary Observatory Strainmeter network a wide array of publically available resources have been created. On the one hand there is the largest network of strainmeters and seismometers on the West Coast. The seismometers are at depths of 450 feet or deeper, eliminating surface noise. The Gladwin strainmeter, at 450 feet or deeper, aligns the San Andreas fault, the San Jacinto Fault, the Cascade Subduction Zone, Mt St Helens Volcano and Yellowstone Caldera. This network combined with an extensive PBO GPS network, provides an excellent laboratory for observing the interaction and progression of motions along the active western plate. After the installation phase ended in 2008, a variety of motions have been observed. In the Pacific Northwest ETS events are recorded on the Glaswin strainmeter and seismometers. Along the San Andreas Fault line near Parkfield creep motions are observed on the Gladwin strianmeter. While in Yellowstone a variety of geophysical events are documented, from earthquakes to the possible motion of ice on Lake Yellowstone. Along with this array of publically available data, a new step has been taken to provide additional resources. The cuttings and core of all drilled borehole have been documented and stored. Images of the drill cuttings will be placed on the UNAVCO PBO website with the purpose to be available on request to researchers. Among these are cuttings in complex fault zones, such as the San Andreas. In Yellowstone National Park, drilling has not occurred in nearly four decades. The PBO strainmeter group has worked with the Yellowstone Park to drill five boreholes. As drilling was difficult due to the hot temperature of the groundwater, boreholes were only drilled to > 400 feet. Cutting samples were taken at five feet intervals, due to the interest in the water circulation effect on the rock and the volcanic stratigraphy. The collection of PBO strainmeter cuttings and cores will be highlighted with accompaniment of geophysical observations that make this large data collection valuable for understanding the interactions of a plate boundary, to using the geologic resources to further the knowledge of structural geology in these regions, hydrology in volcanic and fault settings, among many other uses.