Seth Moran, Ph.D.
My professional career has largely been devoted to the study of active volcanoes and volcano seismology, with a hiatus in 2015-2020 to serve as the Scientist-in-Charge of the Cascades Volcano Observatory. I am interested in all things volcanoes and seismology, as well as hazards in general. I'm also interested in science communication and in seeking ways to build more inclusive workplace environments.
Science and Products
Filter Total Items: 53
Source mechanism of small long-period events at Mount St. Helens in July 2005 using template matching, phase-weighted stacking, and full-waveform inversion
Long-period (LP, 0.5-5 Hz) seismicity, observed at volcanoes worldwide, is a recognized signature of unrest and eruption. Cyclic LP “drumbeating” was the characteristic seismicity accompanying the sustained dome-building phase of the 2004–2008 eruption of Mount St. Helens (MSH), WA. However, together with the LP drumbeating was a near-continuous, randomly occurring series of tiny LP seismic events
Authors
Robin S. Matoza, Bernard A. Chouet, Phillip B. Dawson, Peter M. Shearer, Matthew M. Haney, Gregory P. Waite, Seth C. Moran, T. Dylan Mikesell
Self-similar rupture implied by scaling properties of volcanic earthquakes occurring during the 2004-2008 eruption of Mount St. Helens, Washington
We analyze a group of 6073 low-frequency earthquakes recorded during a week-long temporary deployment of broadband seismometers at distances of less than 3 km from the crater at Mount St. Helens in September of 2006. We estimate the seismic moment (M0) and spectral corner frequency (f0) using a spectral ratio approach for events with a high signal-to-noise (SNR) ratio that have a cross-correlation
Authors
Rebecca M. Harrington, Grzegorz Kwiatek, Seth C. Moran
Attenuation and scattering tomography of the deep plumbing system of Mount St. Helens
We present a combined 3-D P wave attenuation, 2-D S coda attenuation, and 3-D S coda scattering tomography model of fluid pathways, feeding systems, and sediments below Mount St. Helens (MSH) volcano between depths of 0 and 18 km. High-scattering and high-attenuation shallow anomalies are indicative of magma and fluid-rich zones within and below the volcanic edifice down to 6 km depth, where a hig
Authors
Luca De Siena, Christine Thomas, Greg P. Waite, Seth C. Moran, Stefan Klemme
Volcanic tremor masks its seismogenic source: Results from a study of noneruptive tremor recorded at Mount St. Helens, Washington
On 2 October 2004, a significant noneruptive tremor episode occurred during the buildup to the 2004–2008 eruption of Mount St. Helens (Washington). This episode was remarkable both because no explosion followed, and because seismicity abruptly stopped following the episode. This sequence motivated us to consider a model for volcanic tremor that does not involve energetic gas release from magma but
Authors
Roger P. Denlinger, Seth C. Moran
Deep long-period earthquakes west of the volcanic arc in Oregon: evidence of serpentine dehydration in the fore-arc mantle wedge
Here we report on deep long-period earthquakes (DLPs) newly observed in four places in western Oregon. The DLPs are noteworthy for their location within the subduction fore arc: 40–80 km west of the volcanic arc, well above the slab, and near the Moho. These “offset DLPs” occur near the top of the inferred stagnant mantle wedge, which is likely to be serpentinized and cold. The lack of fore-arc DL
Authors
John E. Vidale, David A. Schmidt, Stephen D. Malone, Alicia J. Hotovec-Ellis, Seth C. Moran, Kenneth C. Creager, Heidi Houston
Evidence for fluid-triggered slip in the 2009 Mount Rainier, Washington earthquake swarm
A vigorous swarm of over 1000 small, shallow earthquakes occurred 20–22 September 2009 beneath Mount Rainier, Washington, including the largest number of events ever recorded in a single day at Rainier since seismic stations were installed on the edifice in 1989. Many events were only clearly recorded on one or two stations on the edifice, or they overlapped in time with other events, and thus onl
Authors
David R. Shelly, Seth C. Moran, Weston A. Thelen
Shallow repeating seismic events under an alpine glacier at Mount Rainier, Washington, USA
We observed several swarms of repeating low-frequency (1–5 Hz) seismic events during a 3 week period in May–June 2010, near the summit of Mount Rainier, Washington, USA, that likely were a result of stick–slip motion at the base of alpine glaciers. The dominant set of repeating events ('multiplets') featured >4000 individual events and did not exhibit daytime variations in recurrence interval or a
Authors
Weston A. Thelen, Kate E. Allstadt, Silvio De Angelis, Stephen D. Malone, Seth C. Moran, John Vidale
Source mechanisms of persistent shallow earthquakes during eruptive and non-eruptive periods between 1981 and 2011 at Mount St. Helens, Washington
Shallow seismicity between 0 and 3-km depth has persisted at Mount St. Helens, Washington (MSH) during both eruptive and non-eruptive periods for at least the past thirty years. In this study we investigate the source mechanisms of shallow volcano-tectonic (VT) earthquakes at MSH by calculating high-quality hypocenter locations and fault plane solutions (FPS) for all VT events recorded during two
Authors
Heather L. Lehto, Diana C. Roman, Seth C. Moran
Faulting within the Mount St. Helens conduit and implications for volcanic earthquakes
The 2004–2008 eruption of Mount St. Helens produced seven dacite spines mantled by cataclastic fault rocks, comprising an outer fault core and an inner damage zone. These fault rocks provide remarkable insights into the mechanical processes that accompany extrusion of degassed magma, insights that are useful in forecasting dome-forming eruptions. The outermost part of the fault core consists of fi
Authors
John S. Pallister, Katharine V. Cashman, Jonathan T. Hagstrum, Nicholas M. Beeler, Seth C. Moran, Roger P. Denlinger
Volcanic earthquakes in Alaska's national parks
Alaska’s national parks contain 11 historically active
volcanoes (Figure 2), which produce thousands of small
earthquakes every year. These earthquakes are voices
of the magmatic and geothermal systems within the
volcanoes. The Alaska Volcano Observatory (AVO), a
joint program of the U.S. Geological Survey, the Geophysical
Institute at the University of Alaska Fairbanks,
and the Alaska Division of
Authors
Stephanie G. Prejean, Seth C. Moran, John A. Power, Michael J. West
Failed magmatic eruptions: Late-stage cessation of magma ascent
When a volcano becomes restless, a primary question is whether the unrest will lead to an eruption. Here we recognize four possible outcomes of a magmatic intrusion: "deep intrusion", "shallow intrusion", "sluggish/viscous magmatic eruption", and "rapid, often explosive magmatic eruption". We define "failed eruptions" as instances in which magma reaches but does not pass the "shallow intrusion" st
Authors
S.C. Moran, C. Newhall, D.C. Roman
Deep long-period earthquakes beneath Washington and Oregon volcanoes
Deep long-period (DLP) earthquakes are an enigmatic type of seismicity occurring near or beneath volcanoes. They are commonly associated with the presence of magma, and found in some cases to correlate with eruptive activity. To more thoroughly understand and characterize DLP occurrence near volcanoes in Washington and Oregon, we systematically searched the Pacific Northwest Seismic Network (PNSN)
Authors
M.L. Nichols, S. D. Malone, Seth C. Moran, Weston A. Thelen, J.E. Vidale
Science and Products
Filter Total Items: 53
Source mechanism of small long-period events at Mount St. Helens in July 2005 using template matching, phase-weighted stacking, and full-waveform inversion
Long-period (LP, 0.5-5 Hz) seismicity, observed at volcanoes worldwide, is a recognized signature of unrest and eruption. Cyclic LP “drumbeating” was the characteristic seismicity accompanying the sustained dome-building phase of the 2004–2008 eruption of Mount St. Helens (MSH), WA. However, together with the LP drumbeating was a near-continuous, randomly occurring series of tiny LP seismic events
Authors
Robin S. Matoza, Bernard A. Chouet, Phillip B. Dawson, Peter M. Shearer, Matthew M. Haney, Gregory P. Waite, Seth C. Moran, T. Dylan Mikesell
Self-similar rupture implied by scaling properties of volcanic earthquakes occurring during the 2004-2008 eruption of Mount St. Helens, Washington
We analyze a group of 6073 low-frequency earthquakes recorded during a week-long temporary deployment of broadband seismometers at distances of less than 3 km from the crater at Mount St. Helens in September of 2006. We estimate the seismic moment (M0) and spectral corner frequency (f0) using a spectral ratio approach for events with a high signal-to-noise (SNR) ratio that have a cross-correlation
Authors
Rebecca M. Harrington, Grzegorz Kwiatek, Seth C. Moran
Attenuation and scattering tomography of the deep plumbing system of Mount St. Helens
We present a combined 3-D P wave attenuation, 2-D S coda attenuation, and 3-D S coda scattering tomography model of fluid pathways, feeding systems, and sediments below Mount St. Helens (MSH) volcano between depths of 0 and 18 km. High-scattering and high-attenuation shallow anomalies are indicative of magma and fluid-rich zones within and below the volcanic edifice down to 6 km depth, where a hig
Authors
Luca De Siena, Christine Thomas, Greg P. Waite, Seth C. Moran, Stefan Klemme
Volcanic tremor masks its seismogenic source: Results from a study of noneruptive tremor recorded at Mount St. Helens, Washington
On 2 October 2004, a significant noneruptive tremor episode occurred during the buildup to the 2004–2008 eruption of Mount St. Helens (Washington). This episode was remarkable both because no explosion followed, and because seismicity abruptly stopped following the episode. This sequence motivated us to consider a model for volcanic tremor that does not involve energetic gas release from magma but
Authors
Roger P. Denlinger, Seth C. Moran
Deep long-period earthquakes west of the volcanic arc in Oregon: evidence of serpentine dehydration in the fore-arc mantle wedge
Here we report on deep long-period earthquakes (DLPs) newly observed in four places in western Oregon. The DLPs are noteworthy for their location within the subduction fore arc: 40–80 km west of the volcanic arc, well above the slab, and near the Moho. These “offset DLPs” occur near the top of the inferred stagnant mantle wedge, which is likely to be serpentinized and cold. The lack of fore-arc DL
Authors
John E. Vidale, David A. Schmidt, Stephen D. Malone, Alicia J. Hotovec-Ellis, Seth C. Moran, Kenneth C. Creager, Heidi Houston
Evidence for fluid-triggered slip in the 2009 Mount Rainier, Washington earthquake swarm
A vigorous swarm of over 1000 small, shallow earthquakes occurred 20–22 September 2009 beneath Mount Rainier, Washington, including the largest number of events ever recorded in a single day at Rainier since seismic stations were installed on the edifice in 1989. Many events were only clearly recorded on one or two stations on the edifice, or they overlapped in time with other events, and thus onl
Authors
David R. Shelly, Seth C. Moran, Weston A. Thelen
Shallow repeating seismic events under an alpine glacier at Mount Rainier, Washington, USA
We observed several swarms of repeating low-frequency (1–5 Hz) seismic events during a 3 week period in May–June 2010, near the summit of Mount Rainier, Washington, USA, that likely were a result of stick–slip motion at the base of alpine glaciers. The dominant set of repeating events ('multiplets') featured >4000 individual events and did not exhibit daytime variations in recurrence interval or a
Authors
Weston A. Thelen, Kate E. Allstadt, Silvio De Angelis, Stephen D. Malone, Seth C. Moran, John Vidale
Source mechanisms of persistent shallow earthquakes during eruptive and non-eruptive periods between 1981 and 2011 at Mount St. Helens, Washington
Shallow seismicity between 0 and 3-km depth has persisted at Mount St. Helens, Washington (MSH) during both eruptive and non-eruptive periods for at least the past thirty years. In this study we investigate the source mechanisms of shallow volcano-tectonic (VT) earthquakes at MSH by calculating high-quality hypocenter locations and fault plane solutions (FPS) for all VT events recorded during two
Authors
Heather L. Lehto, Diana C. Roman, Seth C. Moran
Faulting within the Mount St. Helens conduit and implications for volcanic earthquakes
The 2004–2008 eruption of Mount St. Helens produced seven dacite spines mantled by cataclastic fault rocks, comprising an outer fault core and an inner damage zone. These fault rocks provide remarkable insights into the mechanical processes that accompany extrusion of degassed magma, insights that are useful in forecasting dome-forming eruptions. The outermost part of the fault core consists of fi
Authors
John S. Pallister, Katharine V. Cashman, Jonathan T. Hagstrum, Nicholas M. Beeler, Seth C. Moran, Roger P. Denlinger
Volcanic earthquakes in Alaska's national parks
Alaska’s national parks contain 11 historically active
volcanoes (Figure 2), which produce thousands of small
earthquakes every year. These earthquakes are voices
of the magmatic and geothermal systems within the
volcanoes. The Alaska Volcano Observatory (AVO), a
joint program of the U.S. Geological Survey, the Geophysical
Institute at the University of Alaska Fairbanks,
and the Alaska Division of
Authors
Stephanie G. Prejean, Seth C. Moran, John A. Power, Michael J. West
Failed magmatic eruptions: Late-stage cessation of magma ascent
When a volcano becomes restless, a primary question is whether the unrest will lead to an eruption. Here we recognize four possible outcomes of a magmatic intrusion: "deep intrusion", "shallow intrusion", "sluggish/viscous magmatic eruption", and "rapid, often explosive magmatic eruption". We define "failed eruptions" as instances in which magma reaches but does not pass the "shallow intrusion" st
Authors
S.C. Moran, C. Newhall, D.C. Roman
Deep long-period earthquakes beneath Washington and Oregon volcanoes
Deep long-period (DLP) earthquakes are an enigmatic type of seismicity occurring near or beneath volcanoes. They are commonly associated with the presence of magma, and found in some cases to correlate with eruptive activity. To more thoroughly understand and characterize DLP occurrence near volcanoes in Washington and Oregon, we systematically searched the Pacific Northwest Seismic Network (PNSN)
Authors
M.L. Nichols, S. D. Malone, Seth C. Moran, Weston A. Thelen, J.E. Vidale