Geology topics

Benjamin A. Pauk

Publications and source records attributed to Benjamin A. Pauk.

3 recordsLinked to original sources

USGS2010

Geodetic constraints on magma movement and withdrawal during the 2006 eruption of Augustine Volcano: Chapter 17 in The 2006 eruption of Augustine Volcano, Alaska

For the first time in the United States, a modern geodetic network of continuously recording Global Positioning System (GPS) receivers has measured a complete eruption cycle at a stratovolcano, Augustine Volcano in Alaska, from the earliest precursory unrest through the return to background quiescence. The on-island network consisted of five continuously recording, telemetered GPS stations, four continuously recording, nontelemetered stations, and about 10 campaign bench marks. The continuous network recorded several distinct and conspicuous signals over the course of the unrest and eruption, starting with a months-long precursory inflation centered beneath the volcano at around sea level. Nearly coincident with the highest volumetric eruption rates, this inflation gave way to a more deep seated deflation that we interpret as a major withdrawal (approx. 25 million m3 of compressed magma) from a nearly cylindrical magma reservoir centered about 5 km below sea level. Detailed analysis of the geodetic time series reveals additional nuance, including the probable upward propagation of a small dike into the edifice in the 60 days or so before the onset of large-scale explosive activity. Comparisons of the geodetic data and their resulting interpretations with other data, such as earthquake hypocenters and petrologically inferred magma-pressure histories, reveal a kinematic, if not mechanical, account of the 2006 eruption that details the shape and location of the magma source region, the means and velocity of magma transport, and the establishment of a short lived volume- (or pressure-) buffering capability held within the magma reservoir. The cumulative deformation over the course of the eruption shows a large signal close in and high on the edifice that decays rapidly with distance. This pattern indicates a small permanent increase in the edifice volume (beyond that added by the surficial lava dome) but also shows that without close-in (<2.5 km from the summit) stations, the eruption might have been invisible to campaign GPS stations alone.

Alaska↗

USGS2010

The Plate Boundary Observatory Permanent Global Positioning System Network on Augustine Volcano before and after the 2006 Eruption: Chapter 19 in The 2006 eruption of Augustine Volcano, Alaska

In September of 2004, UNAVCO and the National Science Foundation (NSF) funded EarthScope Plate Boundary Observatory (PBO) installed five permanent Continuous Global Positioning System (CGPS) stations on Augustine Volcano, supplementing one existing CGPS station operated by the Alaska Volcano Observatory. All six CGPS stations proved crucial to scientists for detecting and monitoring the precursory deformation of the volcano beginning in early May 2005, as well as for monitoring the many subsequent small inflationary and deflationary episodes that characterized the 2006 eruption. Following the eruption, in September of 2006, PBO added six additional permanent CGPS stations. The 2006 eruption and its precursors were the first significant activity of the volcano in 20 years and the PBO CGPS network provided an unprecedented opportunity to monitor and detect volcanic ground deformation on an erupting Alaskan stratovolcano. Data from the new CGPS stations coupled with the existing seismic stations provided scientists with the first real opportunity to use geodetic data and real time seismic data to assess the volcanic hazards before, during, and after an Alaskan eruption.

Alaska↗

USGS2001

Global Positioning System (GPS) survey of Augustine Volcano, Alaska, August 3-8, 2000: data processing, geodetic coordinates and comparison with prior geodetic surveys

Between August 3 and 8,2000,the Alaska Volcano Observatory completed a Global Positioning System (GPS) survey at Augustine Volcano, Alaska. Augustine is a frequently active calcalkaline volcano located in the lower portion of Cook Inlet (fig. 1), with reported eruptions in 1812, 1882, 1909?, 1935, 1964, 1976, and 1986 (Miller et al., 1998). Geodetic measurements using electronic and optical surveying techniques (EDM and theodolite) were begun at Augustine Volcano in 1986. In 1988 and 1989, an island-wide trilateration network comprising 19 benchmarks was completed and measured in its entirety (Power and Iwatsubo, 1998). Partial GPS surveys of the Augustine Island geodetic network were completed in 1992 and 1995; however, neither of these surveys included all marks on the island.Additional GPS measurements of benchmarks A5 and A15 (fig. 2) were made during the summers of 1992, 1993, 1994, and 1996. The goals of the 2000 GPS survey were to:1) re-measure all existing benchmarks on Augustine Island using a homogeneous set of GPS equipment operated in a consistent manner, 2) add measurements at benchmarks on the western shore of Cook Inlet at distances of 15 to 25 km, 3) add measurements at an existing benchmark (BURR) on Augustine Island that was not previously surveyed, and 4) add additional marks in areas of the island thought to be actively deforming. The entire survey resulted in collection of GPS data at a total of 24 sites (fig. 1 and 2). In this report we describe the methods of GPS data collection and processing used at Augustine during the 2000 survey. We use this data to calculate coordinates and elevations for all 24 sites surveyed. Data from the 2000 survey is then compared toelectronic and optical measurements made in 1988 and 1989. This report also contains a general description of all marks surveyed in 2000 and photographs of all new marks established during the 2000 survey (Appendix A).

Alaska↗