Phillip Dawson

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.

Biography

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, Menlo Park, 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. 

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Publications:

[1] P. B. Dawson, H. M. Iyer, and J. R. Evans. Seismic study of the Ihla São Miguel, Açores. Technical report, Instituto Nacional de Meterologia e Geofisica, 1984.

[2] P. B. Dawson, A. R. Da Silva, H. M. Iyer, and J. R. Evans. Seismic study of the Agua de Pau Geothermal Project, São Miguel, Açores. Geothermal Resource Council Transactions, 9(II):401-406, 1985.

[3] P. B. Dawson, R. Cutler, and J. R. Evans. HP-85 program "HYP85" an earthquake location program. U.S. Geological Survey Open-File Report, 85-243:33 p., 1985.

[4] D. A. Stauber, H. M. Iyer, W. D. Mooney, and P. B. Dawson. Three-dimensional P-velocity structure of the summit caldera of Newberry volcano, Oregon. Geothermal Resource Council Transactions, 9(II):411-415, 1985.

[5] P. A. Berge, J. R. Evans, J. J. Zucca, W. M. Kohler, W. D. Mooney, P. B. Dawson, and M. H. Smith. High-resolution seismic investigation of the Medicine Lake Volcano, California. U.S. Geological Survey Open-File Report, 86-362:101 p., 1986.

[6] P. B. Dawson and D. A. Stauber. Data report for a three-dimensional high-resolution P-velocity structural investigation of Newberry Volcano, Oregon, using seismic tomography. U.S. Geological Survey Open-File Report, 86-352:122 p., 1986.

[7] J. R. Evans, D. A. Stauber, and P. B. Dawson. Prospecting for shallow magma chambers in the Cascades using seismic tomography. V. E. McKelvey Forum on Mineral and Energy Resources, U. S. Geological Survey Circular, 974:15-16, 1986.

[8] P. B. Dawson and H. M. Iyer. Current USGS research using teleseismic residuals at Long Valley, California. PASSCAL Newsletter, 4(9-10), 1987.

[9] C. O. Sanders, P. B. Dawson, W. L. Ellsworth, J. R. Evans, D. P. Hill, and H. M. Iyer. The seismological search for magma. Geothermal Resources Council Transactions, 11(385-390), 1987.

[10] P. B. Dawson. "CAT SCAN" Long Valley, California. Earth in Space, 1(5):14, 1989.

[11] P. B. Dawson, H. M. Iyer, A. R. Da Silva, and J. R. Evans. Seismicity and crustal structure in the Aqua de Pau volcano region, São Miguel, Açores. U.S. Geological Survey Open-File Report, 89-331:74 p., 1989.

[12] P. B. Dawson, J. R. Evans, and H. M. Iyer. Teleseismic tomography of the compressional wave velocity structure beneath the Long Valley Region, California. Journal of Geophysical Research: Solid Earth, 95(B7):11021-11050, 1990.

[13] H. M. Iyer, J.R. Evans, P. B. Dawson, D. A. Stauber, and U. Achauer. Differences in magma storage in different volcanic environments as revealed by seismic tomography; silicic volcanic centers and subduction-related volcanoes. In M. P. Ryan, editor, Magma Transport and Storage, pages 293-316. Wiley, New York, 1990.

[14] R. A. Harris, H. M. Iyer, and P. B. Dawson. Imaging the Juan de Fuca plate beneath southern Oregon using teleseismic P wave residuals. Journal of Geophysical Research: Solid Earth, 96(B12):19879-19889, 1991.

[15] B. A. Chouet, P. B. Dawson, S. Falsaperla, and E. Privitera. A characterization of long-period events recorded during the eruptive activity of Mount Etna, Italy in 1992. Acta Vulcanologica, 4:81-86, 1992.

[16] P. B. Dawson, H. M. Iyer, and J. R. Evans. Three-dimensional imaging of the crust and upper mantle in the Long Valley-Mono Craters region, California, using teleseismic P-wave residuals. In R. Scarpa, P. Gasparini, and K. Aki, editors, Volcanic Seismology, pages 339-358. Springer Berlin Heidelberg, 1992.

[17] H. M. Iyer and P. B. Dawson. Imaging volcanoes using teleseismic tomography. In H. M. Iyer and K. Hirahara, editors, Seismic Tomography Theory and Practice, pages 466-492. Chapman and Hall, 1993.

[18] C. M. Weiland, L. K. Steck, P. B. Dawson, and V. A. Korneev. Nonlinear teleseismic tomography at Long Valley Caldera, using three-dimensional minimum travel time ray tracing. Journal of Geophysical Research: Solid Earth, 100(B10):20379-20390, 1995.

[19] H. M. Benz, B. A. Chouet, P. B. Dawson, J. C. Lahr, R. A. Page, and J. A. Hole. Three dimensional P and S wave velocity structure of Redoubt Volcano, Alaska. Journal of Geophysical Research: Solid Earth, 101(B4):8111-8128, 1996.

[20] P. B. Dawson. Data report for a seismic study of the P and S wave velocity structure of Redoubt Volcano, Alaska. U.S. Geological Survey Open-File Report, 96-703:43 p., 1996.

[21] B. A. Chouet, G. Saccorotti, M. Martini, P. B. Dawson, G. De Luca, G. Milana, and R. Scarpa. Source and path effects in the wavefields of tremor and explosions at Stromboli Volcano, Italy. Journal of Geophysical Research: Solid Earth, 102(B7):15129-15150, 1997.

[22] B. A. Chouet, P. B. Dawson, G. De Luca, M. Martini, G. Milana, G. Saccorotti, and R. Scarpa. Array analyses of seismic sources at Stromboli. Acta Vulcanologica, 10:367-382, 1998.

[23] B. A. Chouet, G. De Luca, G. Milana, P. B. Dawson, M. Martini, and R. Scarpa. Shallow velocity structure of Stromboli Volcano, Italy, derived from small-aperture array measurements of strombolian tremor. Bulletin of the Seismological Society of America, 88(3):653-666, 1998.

[24] P. B. Dawson, C. Dietel, B. A. Chouet, K. Honma, T. Ohminato, and P. Okubo. A digitally telemetered broadband seismic network at Kilauea Volcano, Hawaii. U.S. Geological Survey Open-File Report, 98-108(108):121 p., 1998.

[25] T. Ohminato, B. A. Chouet, P. B. Dawson, and S. Kedar. Waveform inversion of very long period impulsive signals associated with magmatic injection beneath Kilauea volcano, Hawaii. Journal of Geophysical Research: Solid Earth, 103(B10):2383923862, 1998.

[26] A. Arciniega-Ceballos, B. A. Chouet, and P. B. Dawson. Very long-period signals associated with vulcanian explosions at Popocatepetl Volcano, Mexico. Geophysical Research Letters, 26(19):3013-3016, 1999.

[27] B. A. Chouet, G. Saccorotti, P. B. Dawson, M. Martini, R. Scarpa, G. De Luca, G. Milana, and M. Cattaneo. Broadband measurements of the sources of explosions at Stromboli Volcano, Italy. Geophysical Research Letters, 26(13):1937-1940, 1999.

[28] P. B. Dawson, B. A. Chouet, P. G. Okubo, A. Villasenor, and H. M. Benz. Three dimensional velocity structure of the Kilauea Caldera, Hawaii. Geophysical Research Letters, 26(18):2805-2808, 1999.

[29] A. Arciniega-Ceballos, C. Valdes-Gonzalez, and P. B. Dawson. Temporal and spectral characteristics of seismicity observed at Popocatepetl Volcano, central Mexico. Journal of Volcanology and Geothermal Research, 102(3):207-216, 2000.

[30] J. Almendros, B. A. Chouet, and P. B. Dawson. Spatial extent of a hydrothermal system at Kilauea Volcano, Hawaii, determined from array analyses of shallow long-period seismicity: 1. method. Journal of Geophysical Research: Solid Earth, 106(B7):13565-13580, 2001.

[31] J. Almendros, B. A. Chouet, and P. B. Dawson. Spatial extent of a hydrothermal system at Kilauea Volcano, Hawaii, determined from array analyses of shallow long-period seismicity: 2. results. Journal of Geophysical Research: Solid Earth, 106(B7):13581-13597, 2001.

[32] S. J. Lane, B. A. Chouet, J. C. Phillips, P. B. Dawson, G. A. Ryan, and E. Hurst. Experimental observations of pressure oscillations and flow regimes in an analogue volcanic system. Journal of Geophysical Research: Solid Earth, 106(B4):6461-6476, 2001.

[33] G. Saccorotti, B. A. Chouet, and P. B. Dawson. Wavefield properties of a shallow long-period event and tremor at Kilauea Volcano, Hawaii. Journal of Volcanology and Geothermal Research, 109(1):163-189, 2001.

[34] T. Tomatsu, H. Kumagai, and P. B. Dawson. Tomographic inversion of P-wave velocity and Q structures beneath the Kirishima volcanic complex, southern Japan, based on finite difference calculations of complex traveltimes. Geophysical Journal International, 146(3):781-794, 2001.

[35] J. Almendros, B. A. Chouet, and P. B. Dawson. Array detection of a moving source. Seismological Research Letters, 73(2):153-165, 2002.

[36] J. Almendros, B. A. Chouet, P. B. Dawson, and T. Bond. Identifying elements of the plumbing system beneath Kilauea Volcano, Hawaii, from the source locations of very-long-period signals. Geophysical Journal International, 148(2):303-312, 2002.

[37] J. Almendros, B. A. Chouet, P. B. Dawson, and C. Huber. Mapping the sources of the seismic wavefield at Kilauea Volcano, Hawaii, using data recorded on multiple seismic antennas. Bulletin of the Seismological Society of America, 92(6):2333-2351, 2002.

[38] S. Falsaperla, E. Privitera, B. A. Chouet, and P. B. Dawson. Analysis of long-period events recorded at Mount Etna (Italy) in 1992, and their relationship to eruptive activity. Journal of Volcanology and Geothermal Research, 114(3):419-440, 2002.

[39] D. Hidayat, B. A. Chouet, B. Voight, P. B. Dawson, and A. Ratdomopurbo. Source mechanism of very-long-period signals accompanying dome growth activity at Merapi Volcano, Indonesia. Geophysical Research Letters, 29(23):33-1 - 33-4, 2002.

[40] D. P. Hill, P. B. Dawson, M. J. S. Johnston, A. M. Pitt, G. Biasi, and K. Smith. Very-long-period volcanic earthquakes beneath Mammoth Mountain, California. Geophysical Research Letters, 29(10):8-1 - 8-4, 2002.

[41] A. Arciniega-Ceballos, B. A. Chouet, and P. B. Dawson. Long-period events and tremor at Popocatepetl Volcano (1994-2000) and their broadband characteristics. Bulletin of Volcanology, 65(2-3):124-135, 2003.

[42] B. A. Chouet, P. B. Dawson, T. Ohminato, M. Martini, G. Saccorotti, F. Giudicepietro, G. De Luca, G. Milana, and R. Scarpa. Source mechanisms of explosions at Stromboli Volcano, Italy, determined from moment-tensor inversions of very-long period data. Journal of Geophysical Research: Solid Earth, 108(B1):ESE 7-1 - ESE 7-25, 2003.

[43] G. Saccorotti, B. A. Chouet, and P. B. Dawson. Shallow-velocity models at the Kilauea Volcano, Hawaii, determined from array analyses of tremor wavefields. Geophysical Journal International, 152(3):633-648, 2003.

[44] P. B. Dawson, D. Whilldin, and B. A. Chouet. Application of near real-time radial semblance to locate the shallow magmatic conduit at Kilauea Volcano, Hawaii. Geophysical Research Letters, 31(21), 2004.

[45] P. B. Dawson. A high price for impertinence. Seismological Research Letters, 75(385-386), 2004.

[46] B. A. Chouet, P. B. Dawson, and A. Arciniega-Ceballos. Source mechanism of vulcanian degassing at Popocatepetl Volcano, Mexico, determined from waveform inversions of very long period signals. Journal of Geophysical Research: Solid Earth, 110(B7), 2005.

[47] H. Kumagai, B. A. Chouet, and P. B. Dawson. Source process of a long-period event at Kilauea Volcano, Hawaii. Geophysical Journal International, 161(1):243-254, 2005.

[48] E. Auger, L. D'Auria, M. Martini, B. A. Chouet, and P. B. Dawson. Real-time monitoring and massive inversion of source parameters of very long period seismic signals: An application to Stromboli Volcano, Italy. Geophysical Research Letters, 33(4), 2006.

[49] B. A. Chouet, P. B. Dawson, and M. Nakano. Dynamics of diffusive bubble growth and pressure recovery in a bubbly rhyolitic melt embedded in an elastic solid. Journal of Geophysical Research: Solid Earth, 111(B7), 2006.

[50] M. Nakano, H. Kumagai, B. A. Chouet, and P. B. Dawson. Waveform inversion of volcano-seismic signals for an extended source. Journal of Geophysical Research: Solid Earth, 112(B2), 2007.

[51] A. Arciniega-Ceballos, B. A. Chouet, P. B. Dawson, and G. Asch. Broadband seismic measurements of degassing activity associated with lava effusion at Popocatepetl Volcano, Mexico. Journal of Volcanology and Geothermal Research, 170(1):12-23, 2008.

[52] B. A. Chouet, P. B. Dawson, and M. Martini. Shallow-conduit dynamics at Stromboli Volcano, Italy, imaged from waveform inversions. S. J. Lane and J. S. Gilbert (eds.), Fluid Motions in Volcanic Conduits: A Source of Seismic and Acoustic Signals, Geological Society of London, 307:57-84, 2008.

[53] B. A. Chouet, P. B. Dawson, and M. Martini. Upper conduit structure and explosion dynamics at Stromboli. S. Calvari, S. Inguaggiato, G. Puglisi, M. Ripepe, M. Rosi (eds), The Stromboli Volcano: An Integrated Study of the 2002-2003 Eruption, American Geophysical Union, Washington, D. C., 182:81-92, 2008.

[54] G. P. Waite, B. A. Chouet, and P. B. Dawson. Eruption dynamics at Mount St. Helens imaged from broadband seismic waveforms: Interaction of the shallow magmatic and hydrothermal systems. Journal of Geophysical Research: Solid Earth, 113(B2), 2008. 

[55] R. A. Harris, M. Barall, R. Archuleta, E. Dunham, B. Aagaard, J.P. Ampuero, H. Bhat, V. Cruz-Atienza, L. Dalguer, P. B. Dawson, et al. The SCEC/USGS dynamic earthquake rupture code verication exercise. Seismological Research Letters, 80(1):119-126, 2009.

[56] B. A. Chouet, P. B. Dawson, M. R. James, and S. J. Lane. Seismic source mechanism of degassing bursts at Kilauea Volcano, Hawaii: Results from waveform inversion in the 10-50 s band. Journal of Geophysical Research: Solid Earth, 115(B9), 2010.

[57] P. B. Dawson, M. C. Benítez, B. A. Chouet, D. Wilson, and P. G. Okubo. Monitoring very-long-period seismicity at Kilauea Volcano, Hawaii. Geophysical Research Letters, 37(18), 2010.

[58] B. A. Chouet and P. B Dawson. Shallow conduit system at Kilauea Volcano, Hawaii, revealed by seismic signals associated with degassing bursts. Journal of Geophysical Research: Solid Earth, 116(B12), 2011.

[59] P. B. Dawson, B. A. Chouet, and J. Power. Determining the seismic source mechanism and location for an explosive eruption with limited observational data: Augustine Volcano, Alaska. Geophysical Research Letters, 38(3), 2011.

[60] A. Arciniega-Ceballos, P. B. Dawson, and B. A. Chouet. Long period seismic source characterization at Popocatepetl Volcano, Mexico. Geophysical Research Letters, 39(20), 2012.

[61] P. B Dawson, M. C. Benítez, J. B. Lowenstern, and B. A. Chouet. Identifying bubble collapse in a hydrothermal system using hidden Markov models. Geophysical Research Letters, 39(1), 2012.

[62] B. A. Chouet and P. B. Dawson. Very long period conduit oscillations induced by rockfalls at Kilauea Volcano, Hawaii. Journal of Geophysical Research: Solid Earth, 118(10):5352-5371, 2013.

[63] M. M. Haney, B. A. Chouet, P. B Dawson, and J. A. Power. Source characterization for an explosion during the 2009 eruption of Redoubt Volcano from very-long-period seismic waves. Journal of Volcanology and Geothermal Research, 259:77-88, 2013.

[64] P. B. Dawson and B. A. Chouet. Characterization of very-long-period seismicity accompanying summit activity at Klauea Volcano, Hawai'i: 2007-2013. Journal of Volcanology and Geothermal Research, 278-279(0):59-85, 2014.

[65] B. A. Chouet and P. B. Dawson. Seismic source dynamics of gas-piston activity at Klauea Volcano, Hawai`i. Journal of Geophysical Research: Solid Earth, 120(4):2525-2560, 2015.

[66] R. S. Matoza, B. A. Chouet, P. B. Dawson, P. M. Shearer, M. M. Haney, G. P. Waite, S. C. Moran, and T. D. Mikesell. Source mechanism of small long-period events at Mount St. Helens in July 2005 using template matching, phase-weighted stacking, and full-waveform inversion. Journal of Geophysical Research: Solid Earth, 120(9):6351-6364, 2015.

[67] B. A. Chouet and P. B. Dawson. Origin of the pulse-like signature of shallow long-period volcano seismicity. Journal of Geophysical Research: Solid Earth, 121(8):5931-5941, 2016. 2016JB013152.

[68] P. B. Dawson, B. A. Chouet, and A. M. Pitt. Tomographic image of a seismically active volcano: Mammoth Mountain California. Journal of Geophysical Research: Solid Earth, 121(1):114-133, 2016.

[69] A. F. Flinders, D. R. Shelly, P. B. Dawson, D. P. Hill, Barbara Tripoli, and Yang Shen. Seismic evidence for significant melt beneath the Long Valley Caldera, California, USA. Geology, 46(9):799, 2018.

[70]  A. J. Hotovec-Ellis, D. R. Shelly, D. P. Hill, A. M. Pitt, P. B. Dawson, and B. A. Chouet. Deep fluid pathways beneath Mammoth mountain, California, illuminated by migrating earthquake swarms. Science Advances, 4(8), 2018.