Evelyn Roeloffs
Evelyn Roeloffs is a Scientist Emeritus in the Earthquake Hazards Program.
Science and Products
Filter Total Items: 21
Report on the Aseismic Slip, Tremor, and Earthquakes Workshop
This report summarizes the discussions and information presented during the workshop on Aseismic Slip, Tremor, and Earthquakes. Workshop goals included improving coordination among those involved in conducting research related to these phenomena, assessing the implications for earthquake hazard assessment, and identifying ways to capitalize on the education and outreach opportunities...
Authors
Joan Gomberg, Evelyn Roeloffs, Anne Trehu, Herb Dragert, Charles Meertens
Borehole observations of continuous strain and fluid pressure: Chapter 9
Strain is expansion, contraction, or distortion of the volcanic edifice and surrounding crust. As a result of magma movement, volcanoes may undergo enormous strain prior to and during eruption. Global Positioning System (GPS) observations can in principle be used to determine strain by taking the difference between two nearby observations and dividing by the distance between them. Two...
Authors
Evelyn A. Roeloffs, A. T. Linde
Implications for prediction and hazard assessment from the 2004 Parkfield earthquake
Obtaining high-quality measurements close to a large earthquake is not easy: one has to be in the right place at the right time with the right instruments. Such a convergence happened, for the first time, when the 28 September 2004 Parkfield, California, earthquake occurred on the San Andreas fault in the middle of a dense network of instruments designed to record it. The resulting data...
Authors
W. H. Bakun, Brad T. Aagaard, B. Dost, William L. Ellsworth, Jeanne L. Hardebeck, Ruth A. Harris, C. Ji, Malcolm J. S. Johnston, John O. Langbein, James J. Lienkaemper, Andrew J. Michael, Jessica R. Murray, R.M. Nadeau, P.A. Reasenberg, M.S. Reichle, Evelyn A. Roeloffs, A. Shakal, Robert W. Simpson, F. Waldhauser
Preliminary report on the 22 December 2003, M 6.5 San Simeon, California earthquake
The Mw 6.5 San Simeon earthquake struck the central California coast on 22 December 2003 at 19:15:56 UTC (11:15:56 am local time.) The epicenter was located 11 km northeast of the town of San Simeon, and 39 km west-northwest of Paso Robles (Figure 1), as reported by the California Integrated Seismic Network (CISN, the California region of the Advanced National Seismic System [ANSS]). The...
Authors
Jeanne L. Hardebeck, John Boatwright, D. Dreger, Rakesh Goel, V. Graizer, Kenneth W. Hudnut, Ji Chen, Lucile M. Jones, John O. Langbein, Jian Lin, Evelyn A. Roeloffs, Robert W. Simpson, K. Stark, Ross S. Stein, John Tinsley
Water-level changes induced by local and distant earthquakes at Long Valley caldera, California
Distant as well as local earthquakes have induced groundwater-level changes persisting for days to weeks at Long Valley caldera, California. Four wells open to formations as deep as 300 m have responded to 16 earthquakes, and responses to two earthquakes in the 3-km-deep Long Valley Exploratory Well (LVEW) show that these changes are not limited to weathered or unconsolidated near...
Authors
Evelyn A. Roeloffs, Michelle Sneed, Devin L. Galloway, Michael L. Sorey, Christopher D. Farrar, James F. Howle, J. Hughes
Water-level changes in response to the 20 December 1994 earthquake near Parkfield, California
We analyze co-seismic changes of water level in nine wells near Parkfield, California, produced by an MD 4.7 earthquake on 20 December 1994 in order to test the hypothesis that co-seismic water-level changes are proportional to co-seismic volumetric strain. For each well, a quantitative relationship between water level and volumetric strain can be inferred from water-level fluctuations...
Authors
Eddie Quilty, Evelyn A. Roeloffs
An updated numerical simulation of the ground-water flow system for the Castle Lake debris dam, Mount St. Helens, Washington, and implications for dam stability against heave
A numerical simulation of the ground-water flow system in the Castle Lake debris dam, calibrated to data from the 1991 and 1992 water years, was used to estimate factors of safety against heave and internal erosion. The Castle Lake debris dam, 5 miles northwest of the summit of Mount St. Helens, impounds 19,000 acre-ft of water that could pose a flood hazard in the event of a lake...
Authors
Evelyn A. Roeloffs
The Loma Prieta, California, earthquake of October 17, 1989: Preseismic observations
The October 17, 1989, Loma Prieta, Calif., Ms=7.1 earthquake provided the first opportunity in the history of fault monitoring in the United States to gather multidisciplinary preearthquake data in the near field of an M=7 earthquake. The data obtained include observations on seismicity, continuous strain, long-term ground displacement, magnetic field, and hydrology. The papers in this...
Authors
Malcolm J. S. Johnston, Jean A. Olson, David P. Hill, Anthony C. Fraser-Smith, Arman Bernardi, Robert A. Helliwell, Paul R. McGill, O.G. Villard, Robert J. Mueller, Randall A. White, William L. Ellsworth, Evelyn A. Roeloffs, Alan T. Linde, M. T. Gladwin, R. L. Gwyther, R.H.G. Hart, Michael Lisowski, James C. Savage, William H. Prescott, Jerry L. Svarc, Mark Hunter Murray, P.G. Silver, N. J. Valette-Silver, Olga Kolbek
Plane-strain shear dislocations moving steadily in linear elastic diffusive solids
This paper derives the stress and pore pressure fields induced by a plane-strain shear (gliding edge) dislocation moving steadily at a constant speed V in a linear elastic, fluid-infiltrated (Biot) solid. Solutions are obtained for the limiting cases in which the plane containing the moving dislocation (y = 0) is permeable and impermeable to the diffusing species. Although the solutions...
Authors
J.W. Rudnicki, Evelyn A. Roeloffs
Science and Products
Filter Total Items: 21
Report on the Aseismic Slip, Tremor, and Earthquakes Workshop
This report summarizes the discussions and information presented during the workshop on Aseismic Slip, Tremor, and Earthquakes. Workshop goals included improving coordination among those involved in conducting research related to these phenomena, assessing the implications for earthquake hazard assessment, and identifying ways to capitalize on the education and outreach opportunities...
Authors
Joan Gomberg, Evelyn Roeloffs, Anne Trehu, Herb Dragert, Charles Meertens
Borehole observations of continuous strain and fluid pressure: Chapter 9
Strain is expansion, contraction, or distortion of the volcanic edifice and surrounding crust. As a result of magma movement, volcanoes may undergo enormous strain prior to and during eruption. Global Positioning System (GPS) observations can in principle be used to determine strain by taking the difference between two nearby observations and dividing by the distance between them. Two...
Authors
Evelyn A. Roeloffs, A. T. Linde
Implications for prediction and hazard assessment from the 2004 Parkfield earthquake
Obtaining high-quality measurements close to a large earthquake is not easy: one has to be in the right place at the right time with the right instruments. Such a convergence happened, for the first time, when the 28 September 2004 Parkfield, California, earthquake occurred on the San Andreas fault in the middle of a dense network of instruments designed to record it. The resulting data...
Authors
W. H. Bakun, Brad T. Aagaard, B. Dost, William L. Ellsworth, Jeanne L. Hardebeck, Ruth A. Harris, C. Ji, Malcolm J. S. Johnston, John O. Langbein, James J. Lienkaemper, Andrew J. Michael, Jessica R. Murray, R.M. Nadeau, P.A. Reasenberg, M.S. Reichle, Evelyn A. Roeloffs, A. Shakal, Robert W. Simpson, F. Waldhauser
Preliminary report on the 22 December 2003, M 6.5 San Simeon, California earthquake
The Mw 6.5 San Simeon earthquake struck the central California coast on 22 December 2003 at 19:15:56 UTC (11:15:56 am local time.) The epicenter was located 11 km northeast of the town of San Simeon, and 39 km west-northwest of Paso Robles (Figure 1), as reported by the California Integrated Seismic Network (CISN, the California region of the Advanced National Seismic System [ANSS]). The...
Authors
Jeanne L. Hardebeck, John Boatwright, D. Dreger, Rakesh Goel, V. Graizer, Kenneth W. Hudnut, Ji Chen, Lucile M. Jones, John O. Langbein, Jian Lin, Evelyn A. Roeloffs, Robert W. Simpson, K. Stark, Ross S. Stein, John Tinsley
Water-level changes induced by local and distant earthquakes at Long Valley caldera, California
Distant as well as local earthquakes have induced groundwater-level changes persisting for days to weeks at Long Valley caldera, California. Four wells open to formations as deep as 300 m have responded to 16 earthquakes, and responses to two earthquakes in the 3-km-deep Long Valley Exploratory Well (LVEW) show that these changes are not limited to weathered or unconsolidated near...
Authors
Evelyn A. Roeloffs, Michelle Sneed, Devin L. Galloway, Michael L. Sorey, Christopher D. Farrar, James F. Howle, J. Hughes
Water-level changes in response to the 20 December 1994 earthquake near Parkfield, California
We analyze co-seismic changes of water level in nine wells near Parkfield, California, produced by an MD 4.7 earthquake on 20 December 1994 in order to test the hypothesis that co-seismic water-level changes are proportional to co-seismic volumetric strain. For each well, a quantitative relationship between water level and volumetric strain can be inferred from water-level fluctuations...
Authors
Eddie Quilty, Evelyn A. Roeloffs
An updated numerical simulation of the ground-water flow system for the Castle Lake debris dam, Mount St. Helens, Washington, and implications for dam stability against heave
A numerical simulation of the ground-water flow system in the Castle Lake debris dam, calibrated to data from the 1991 and 1992 water years, was used to estimate factors of safety against heave and internal erosion. The Castle Lake debris dam, 5 miles northwest of the summit of Mount St. Helens, impounds 19,000 acre-ft of water that could pose a flood hazard in the event of a lake...
Authors
Evelyn A. Roeloffs
The Loma Prieta, California, earthquake of October 17, 1989: Preseismic observations
The October 17, 1989, Loma Prieta, Calif., Ms=7.1 earthquake provided the first opportunity in the history of fault monitoring in the United States to gather multidisciplinary preearthquake data in the near field of an M=7 earthquake. The data obtained include observations on seismicity, continuous strain, long-term ground displacement, magnetic field, and hydrology. The papers in this...
Authors
Malcolm J. S. Johnston, Jean A. Olson, David P. Hill, Anthony C. Fraser-Smith, Arman Bernardi, Robert A. Helliwell, Paul R. McGill, O.G. Villard, Robert J. Mueller, Randall A. White, William L. Ellsworth, Evelyn A. Roeloffs, Alan T. Linde, M. T. Gladwin, R. L. Gwyther, R.H.G. Hart, Michael Lisowski, James C. Savage, William H. Prescott, Jerry L. Svarc, Mark Hunter Murray, P.G. Silver, N. J. Valette-Silver, Olga Kolbek
Plane-strain shear dislocations moving steadily in linear elastic diffusive solids
This paper derives the stress and pore pressure fields induced by a plane-strain shear (gliding edge) dislocation moving steadily at a constant speed V in a linear elastic, fluid-infiltrated (Biot) solid. Solutions are obtained for the limiting cases in which the plane containing the moving dislocation (y = 0) is permeable and impermeable to the diffusing species. Although the solutions...
Authors
J.W. Rudnicki, Evelyn A. Roeloffs