John W. Ewert (Former Employee)
Science and Products
Filter Total Items: 34
Newberry Volcano—Central Oregon’s sleeping giant Newberry Volcano—Central Oregon’s sleeping giant
Hidden in plain sight, Oregon's massive Newberry Volcano is the largest volcano in the Cascades volcanic arc and covers an area the size of Rhode Island. Unlike familiar cone-shaped Cascades volcanoes, Newberry was built into the shape of a broad shield by repeated eruptions over 500,000 years. About 65,000 years ago a major explosion and collapse event created a large volcanic...
Authors
Julie M. Donnelly-Nolan, Wendy K. Stovall, David W. Ramsey, John W. Ewert, Robert A. Jensen
Volcano-Monitoring Instrumentation in the United States, 2008 Volcano-Monitoring Instrumentation in the United States, 2008
The United States is one of the most volcanically active countries in the world. According to the global volcanism database of the Smithsonian Institution, the United States (including its Commonwealth of the Northern Mariana Islands) is home to about 170 volcanoes that are in an eruptive phase, have erupted in historical time, or have not erupted recently but are young enough (eruptions...
Authors
Marianne Guffanti, Angela K. Diefenbach, John W. Ewert, David W. Ramsey, Peter F. Cervelli, Steven P. Schilling
Chronology and references of volcanic eruptions and selected unrest in the United States, 1980-2008 Chronology and references of volcanic eruptions and selected unrest in the United States, 1980-2008
The United States ranks as one of the top countries in the world in the number of young, active volcanoes within its borders. The United States, including the Commonwealth of the Northern Mariana Islands, is home to approximately 170 geologically active (age
Authors
Angela K. Diefenbach, Marianne Guffanti, John W. Ewert
Preliminary spreadsheet of eruption source parameters for volcanoes of the world Preliminary spreadsheet of eruption source parameters for volcanoes of the world
Volcanic eruptions that spew tephra into the atmosphere pose a hazard to jet aircraft. For this reason, the International Civil Aviation Organization (ICAO) has designated nine Volcanic Ash and Aviation Centers (VAACs) around the world whose purpose is to track ash clouds from eruptions and notify aircraft so that they may avoid these ash clouds. During eruptions, VAACs and their...
Authors
Larry G. Mastin, Marianne Guffanti, John W. Ewert, Jessica Spiegel
A multidisciplinary effort to assign realistic source parameters to models of volcanic ash-cloud transport and dispersion during eruptions A multidisciplinary effort to assign realistic source parameters to models of volcanic ash-cloud transport and dispersion during eruptions
During volcanic eruptions, volcanic ash transport and dispersion models (VATDs) are used to forecast the location and movement of ash clouds over hours to days in order to define hazards to aircraft and to communities downwind. Those models use input parameters, called “eruption source parameters”, such as plume height H, mass eruption rate Ṁ, duration D, and the mass fraction m63 of...
Authors
Larry G. Mastin, Marianne C. Guffanti, R. Servranckx, P. Webley, S. Barsotti, K. Dean, A. Durant, John W. Ewert, A. Neri, W.I. Rose, David J. Schneider, Lee Siebert, B. Stunder, G. Swanson, A. Tupper, A. Volentik, Christopher F. Waythomas
The unexpected awakening of Chaitén Volcano, Chile The unexpected awakening of Chaitén Volcano, Chile
On 2 May 2008, a large eruption began unexpectedly at the inconspicuous Chaitén volcano in Chile's southern volcanic zone. Ash columns abruptly jetted from the volcano into the stratosphere, followed by lava dome effusion and continuous low-altitude ash plumes [Lara, 2009]. Apocalyptic photographs of eruption plumes suffused with lightning were circulated globally. Effects of the...
Authors
Simon A. Carn, John S. Zogorski, Luis Lara, John W. Ewert, Sebastian Watt, Alfred J. Prata, Ronald J. Thomas, Gustavo Villarosa
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 34
Newberry Volcano—Central Oregon’s sleeping giant Newberry Volcano—Central Oregon’s sleeping giant
Hidden in plain sight, Oregon's massive Newberry Volcano is the largest volcano in the Cascades volcanic arc and covers an area the size of Rhode Island. Unlike familiar cone-shaped Cascades volcanoes, Newberry was built into the shape of a broad shield by repeated eruptions over 500,000 years. About 65,000 years ago a major explosion and collapse event created a large volcanic...
Authors
Julie M. Donnelly-Nolan, Wendy K. Stovall, David W. Ramsey, John W. Ewert, Robert A. Jensen
Volcano-Monitoring Instrumentation in the United States, 2008 Volcano-Monitoring Instrumentation in the United States, 2008
The United States is one of the most volcanically active countries in the world. According to the global volcanism database of the Smithsonian Institution, the United States (including its Commonwealth of the Northern Mariana Islands) is home to about 170 volcanoes that are in an eruptive phase, have erupted in historical time, or have not erupted recently but are young enough (eruptions...
Authors
Marianne Guffanti, Angela K. Diefenbach, John W. Ewert, David W. Ramsey, Peter F. Cervelli, Steven P. Schilling
Chronology and references of volcanic eruptions and selected unrest in the United States, 1980-2008 Chronology and references of volcanic eruptions and selected unrest in the United States, 1980-2008
The United States ranks as one of the top countries in the world in the number of young, active volcanoes within its borders. The United States, including the Commonwealth of the Northern Mariana Islands, is home to approximately 170 geologically active (age
Authors
Angela K. Diefenbach, Marianne Guffanti, John W. Ewert
Preliminary spreadsheet of eruption source parameters for volcanoes of the world Preliminary spreadsheet of eruption source parameters for volcanoes of the world
Volcanic eruptions that spew tephra into the atmosphere pose a hazard to jet aircraft. For this reason, the International Civil Aviation Organization (ICAO) has designated nine Volcanic Ash and Aviation Centers (VAACs) around the world whose purpose is to track ash clouds from eruptions and notify aircraft so that they may avoid these ash clouds. During eruptions, VAACs and their...
Authors
Larry G. Mastin, Marianne Guffanti, John W. Ewert, Jessica Spiegel
A multidisciplinary effort to assign realistic source parameters to models of volcanic ash-cloud transport and dispersion during eruptions A multidisciplinary effort to assign realistic source parameters to models of volcanic ash-cloud transport and dispersion during eruptions
During volcanic eruptions, volcanic ash transport and dispersion models (VATDs) are used to forecast the location and movement of ash clouds over hours to days in order to define hazards to aircraft and to communities downwind. Those models use input parameters, called “eruption source parameters”, such as plume height H, mass eruption rate Ṁ, duration D, and the mass fraction m63 of...
Authors
Larry G. Mastin, Marianne C. Guffanti, R. Servranckx, P. Webley, S. Barsotti, K. Dean, A. Durant, John W. Ewert, A. Neri, W.I. Rose, David J. Schneider, Lee Siebert, B. Stunder, G. Swanson, A. Tupper, A. Volentik, Christopher F. Waythomas
The unexpected awakening of Chaitén Volcano, Chile The unexpected awakening of Chaitén Volcano, Chile
On 2 May 2008, a large eruption began unexpectedly at the inconspicuous Chaitén volcano in Chile's southern volcanic zone. Ash columns abruptly jetted from the volcano into the stratosphere, followed by lava dome effusion and continuous low-altitude ash plumes [Lara, 2009]. Apocalyptic photographs of eruption plumes suffused with lightning were circulated globally. Effects of the...
Authors
Simon A. Carn, John S. Zogorski, Luis Lara, John W. Ewert, Sebastian Watt, Alfred J. Prata, Ronald J. Thomas, Gustavo Villarosa
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.