Phillip Dawson is a geophysicist with the U.S. Geological Survey’s Volcano Science Center, focusing on theoretical and experimental investigations of active volcanism and volcanic processes.
Phillip Dawson hails from a small town located on the flank of one of the world's largest stratovolcanoes - Mount Shasta, California. Who wouldn't want to pursue a career studying volcanoes at the USGS given that background?
He currently works as a geophysicist on the Seismology of Magmatic Injection project at the California Volcano Observatory, Moffett Field, California. This project is dedicated to understanding the underlying physics driving volcanic seismicity and processes through the use of detailed field experiments and the application, modification, and extension of existing seismic methods and theories. Objectives include: quantification of volcanic velocity structure using tomography and surface-wave dispersion inversions; inversion of broadband waveform data to quantify magma transport processes; determining the effect of tilt on modern broadband seismic sensors, and correcting for this effect using waveform inversions; quantification of the effects of 3D topography and structure on seismic wave propagation; using dense small-aperture arrays to identify source, path, and site effects in tremor wavefields; quantification of the source parameters of long-period (LP) and very-long-period (VLP) volcanic seismicity; and developing techniques to enable the accurate identification of volcanic seismicity.
Science and Products
Filter Total Items: 28
High-rate very-long-period seismicity at Yasur volcano, Vanuatu: source mechanism and decoupling from surficial explosions and infrasound
Yasur volcano, Vanuatu is a continuously active open-vent basaltic-andesite stratocone with persistent and long-lived eruptive activity. We present results from a seismo-acoustic field experiment at Yasur, providing locally dense broad-band seismic and infrasonic network coverage from 2016 July 27 to August 3. We corroborate our seismo-acoustic observations with coincident video data from cameras
Sources of volcanic tremor associated with the summit caldera collapse during the 2018 east rift eruption of Kīlauea Volcano, Hawai'i
Volcanic tremor occurring at the beginning of the 2018 Kīlauea eruption is characterized using both seismic and tilt data recorded at the Kīlauea summit. An automatic seismic network-based approach detects several types of tremor including (a) 0.5–1 Hz long-period tremor preceding the eruption, located at the south-southwest edge of Halema'uma'u Crater and attributed to the quasi-steady radiation
Origin and properties of hydrothermal tremor at Lone Star Geyser, Yellowstone National Park, USA
Geysers are rare geologic features that intermittently discharge liquid water and steam driven by heating and decompression boiling. The cause of variability in eruptive styles and the associated seismic signals are not well understood. Data collected from five broadband seismometers at Lone Star Geyser, Yellowstone National Park are used to determine the properties, location, and temporal pattern
Very‐long‐period (VLP) seismic artifacts during the 2018 caldera collapse at Kīlauea, Hawaii
Throughout the 2018 eruption of Kīlauea volcano (Hawai‘i), episodic collapses of a portion of the volcano’s summit caldera produced repeated Mw 4.9–5.3 earthquakes. Each of these 62 events was characterized by a very‐long‐period (VLP) seismic signal (>40 s). Although collapses in the later stage of the eruption produced earthquakes with significant amplitude clipping on near‐summit broadband se
Observations of an extreme atmospheric river storm with a diverse sensor network
Observational networks enhance real‐time situational awareness for emergency and water resource management during extreme weather events. We present examples of how a diverse, multitiered observational network in California provided insights into hydrometeorological processes and impacts during a 3‐day atmospheric river storm centered on 14 February 2019. This network, which has been developed ove
Microseismic events associated with the Oroville Dam spillway
On 14 February 2017, two small (equivalent MD 0.8 and 1.0) seismic events occurred in proximity to the Oroville Dam in the Sierra Nevada foothills, California. To examine possible causal relationships between these events and reservoir operations, including the spillway failure starting prior to these events, we applied a new optimized template matching approach to seismic data between May 1993 -
Deep fluid pathways beneath Mammoth Mountain, California, illuminated by migrating earthquake swarms
Although most volcanic seismicity is shallow (within several kilometers of the surface), some volcanoes exhibit deeper seismicity (10 to 30+ km) that may reflect active processes such as magma resupply and volatile transfer. One such volcano is Mammoth Mountain, California, which has also recently exhibited high rates of CO2 discharge at the surface. We perform high-resolution earthquake detection
Seismic evidence for significant melt beneath the Long Valley Caldera, California, USA
A little more than 760 ka ago, a supervolcano on the eastern edge of California (United States) underwent one of North America's largest Quaternary explosive eruptions. Over this ~6-day-long eruption, pyroclastic flows blanketed the surrounding ~50 km with more than 1400 km3 of the now-iconic Bishop Tuff, with ashfall reaching as far east as Nebraska. Collapse of the volcano's magma reservoir crea
The SCEC/USGS dynamic earthquake rupture code verification exercise
Numerical simulations of earthquake rupture dynamics are now common, yet it has been difficult to test the validity of these simulations because there have been few field observations and no analytic solutions with which to compare the results. This paper describes the Southern California Earthquake Center/U.S. Geological Survey (SCEC/USGS) Dynamic Earthquake Rupture Code Verification Exercise, wh
Waveform inversion of volcano-seismic signals for an extended source
We propose a method to investigate the dimensions and oscillation characteristics of the source of volcano‐seismic signals based on waveform inversion for an extended source. An extended source is realized by a set of point sources distributed on a grid surrounding the centroid of the source in accordance with the source geometry and orientation. The source‐time functions for all point sources are
Real-time monitoring and massive inversion of source parameters of very long period seismic signals: An application to Stromboli Volcano, Italy
We present a comprehensive processing tool for the real‐time analysis of the source mechanism of very long period (VLP) seismic data based on waveform inversions performed in the frequency domain for a point source. A search for the source providing the best‐fitting solution is conducted over a three‐dimensional grid of assumed source locations, in which the Green's functions associated with each
Application of near real-time radial semblance to locate the shallow magmatic conduit at Kilauea Volcano, Hawaii
Radial Semblance is applied to broadband seismic network data to provide source locations of Very-Long-Period (VLP) seismic energy in near real time. With an efficient algorithm and adequate network coverage, accurate source locations of VLP energy are derived to quickly locate the shallow magmatic conduit system at Kilauea Volcano, Hawaii. During a restart in magma flow following a brief pause in
Science and Products
- Publications
Filter Total Items: 28
High-rate very-long-period seismicity at Yasur volcano, Vanuatu: source mechanism and decoupling from surficial explosions and infrasound
Yasur volcano, Vanuatu is a continuously active open-vent basaltic-andesite stratocone with persistent and long-lived eruptive activity. We present results from a seismo-acoustic field experiment at Yasur, providing locally dense broad-band seismic and infrasonic network coverage from 2016 July 27 to August 3. We corroborate our seismo-acoustic observations with coincident video data from camerasSources of volcanic tremor associated with the summit caldera collapse during the 2018 east rift eruption of Kīlauea Volcano, Hawai'i
Volcanic tremor occurring at the beginning of the 2018 Kīlauea eruption is characterized using both seismic and tilt data recorded at the Kīlauea summit. An automatic seismic network-based approach detects several types of tremor including (a) 0.5–1 Hz long-period tremor preceding the eruption, located at the south-southwest edge of Halema'uma'u Crater and attributed to the quasi-steady radiationOrigin and properties of hydrothermal tremor at Lone Star Geyser, Yellowstone National Park, USA
Geysers are rare geologic features that intermittently discharge liquid water and steam driven by heating and decompression boiling. The cause of variability in eruptive styles and the associated seismic signals are not well understood. Data collected from five broadband seismometers at Lone Star Geyser, Yellowstone National Park are used to determine the properties, location, and temporal patternVery‐long‐period (VLP) seismic artifacts during the 2018 caldera collapse at Kīlauea, Hawaii
Throughout the 2018 eruption of Kīlauea volcano (Hawai‘i), episodic collapses of a portion of the volcano’s summit caldera produced repeated Mw 4.9–5.3 earthquakes. Each of these 62 events was characterized by a very‐long‐period (VLP) seismic signal (>40 s). Although collapses in the later stage of the eruption produced earthquakes with significant amplitude clipping on near‐summit broadband seObservations of an extreme atmospheric river storm with a diverse sensor network
Observational networks enhance real‐time situational awareness for emergency and water resource management during extreme weather events. We present examples of how a diverse, multitiered observational network in California provided insights into hydrometeorological processes and impacts during a 3‐day atmospheric river storm centered on 14 February 2019. This network, which has been developed oveMicroseismic events associated with the Oroville Dam spillway
On 14 February 2017, two small (equivalent MD 0.8 and 1.0) seismic events occurred in proximity to the Oroville Dam in the Sierra Nevada foothills, California. To examine possible causal relationships between these events and reservoir operations, including the spillway failure starting prior to these events, we applied a new optimized template matching approach to seismic data between May 1993 -Deep fluid pathways beneath Mammoth Mountain, California, illuminated by migrating earthquake swarms
Although most volcanic seismicity is shallow (within several kilometers of the surface), some volcanoes exhibit deeper seismicity (10 to 30+ km) that may reflect active processes such as magma resupply and volatile transfer. One such volcano is Mammoth Mountain, California, which has also recently exhibited high rates of CO2 discharge at the surface. We perform high-resolution earthquake detectionSeismic evidence for significant melt beneath the Long Valley Caldera, California, USA
A little more than 760 ka ago, a supervolcano on the eastern edge of California (United States) underwent one of North America's largest Quaternary explosive eruptions. Over this ~6-day-long eruption, pyroclastic flows blanketed the surrounding ~50 km with more than 1400 km3 of the now-iconic Bishop Tuff, with ashfall reaching as far east as Nebraska. Collapse of the volcano's magma reservoir creaThe SCEC/USGS dynamic earthquake rupture code verification exercise
Numerical simulations of earthquake rupture dynamics are now common, yet it has been difficult to test the validity of these simulations because there have been few field observations and no analytic solutions with which to compare the results. This paper describes the Southern California Earthquake Center/U.S. Geological Survey (SCEC/USGS) Dynamic Earthquake Rupture Code Verification Exercise, whWaveform inversion of volcano-seismic signals for an extended source
We propose a method to investigate the dimensions and oscillation characteristics of the source of volcano‐seismic signals based on waveform inversion for an extended source. An extended source is realized by a set of point sources distributed on a grid surrounding the centroid of the source in accordance with the source geometry and orientation. The source‐time functions for all point sources areReal-time monitoring and massive inversion of source parameters of very long period seismic signals: An application to Stromboli Volcano, Italy
We present a comprehensive processing tool for the real‐time analysis of the source mechanism of very long period (VLP) seismic data based on waveform inversions performed in the frequency domain for a point source. A search for the source providing the best‐fitting solution is conducted over a three‐dimensional grid of assumed source locations, in which the Green's functions associated with eachApplication of near real-time radial semblance to locate the shallow magmatic conduit at Kilauea Volcano, Hawaii
Radial Semblance is applied to broadband seismic network data to provide source locations of Very-Long-Period (VLP) seismic energy in near real time. With an efficient algorithm and adequate network coverage, accurate source locations of VLP energy are derived to quickly locate the shallow magmatic conduit system at Kilauea Volcano, Hawaii. During a restart in magma flow following a brief pause in