Sustained Long-Period Seismicity at Shishaldin Volcano, Alaska
From September 1999 through April 2004, Shishaldin Volcano, Aleutian Islands, Alaska, exhibited a continuous and extremely high level of background seismicity. This activity consisted of many hundreds to thousands of long-period (LP; 1–2 Hz) earthquakes per day, recorded by a 6-station monitoring...
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ftunisfloridatam:oai:digitalcommons.usf.edu:geo_facpub-1310 2024-09-15T18:41:27+00:00 Sustained Long-Period Seismicity at Shishaldin Volcano, Alaska Petersen, Tanja Caplan-Auerbach, Jacqueline McNutt, Stephen R. 2006-03-15T08:00:00Z https://digitalcommons.usf.edu/geo_facpub/311 https://doi.org/10.1016/j.jvolgeores.2005.09.003 unknown Digital Commons @ University of South Florida https://digitalcommons.usf.edu/geo_facpub/311 doi:10.1016/j.jvolgeores.2005.09.003 https://doi.org/10.1016/j.jvolgeores.2005.09.003 School of Geosciences Faculty and Staff Publications Shishaldin volcano volcano seismology long-period earthquakes Earth Sciences article 2006 ftunisfloridatam https://doi.org/10.1016/j.jvolgeores.2005.09.003 2024-08-23T08:09:15Z From September 1999 through April 2004, Shishaldin Volcano, Aleutian Islands, Alaska, exhibited a continuous and extremely high level of background seismicity. This activity consisted of many hundreds to thousands of long-period (LP; 1–2 Hz) earthquakes per day, recorded by a 6-station monitoring network around Shishaldin. The LP events originate beneath the summit at shallow depths (0–3 km). Volcano tectonic events and tremor have rarely been observed in the summit region. Such a high rate of LP events with no eruption suggests that a steady state process has been occurring ever since Shishaldin last erupted in April–May 1999. Following the eruption, the only other signs of volcanic unrest have been occasional weak thermal anomalies and an omnipresent puffing volcanic plume. The LP waveforms are nearly identical for time spans of days to months, but vary over longer time scales. The observations imply that the spatially close source processes are repeating, stable and non-destructive. Event sizes vary, but the rate of occurrence remains roughly constant. The events range from magnitude ∼ 0.1 to 1.8, with most events having magnitudes < 1.0. The observations suggest that the conduit system is open and capable of releasing a large amount of energy, approximately equivalent to at least one magnitude 1.8–2.6 earthquake per day. The rate of observed puffs (1 per minute) in the steam plume is similar to the typical seismic rates, suggesting that the LP events are directly related to degassing processes. However, the source mechanism, capable of producing one LP event about every 0.5–5 min, is still poorly understood. Shishaldin's seismicity is unusual in its sustained high rate of LP events without accompanying eruptive activity. Every indication is that the high rate of seismicity will continue without reflecting a hazardous state. Sealing of the conduit and/or change in gas flux, however, would be expected to change Shishaldin's behavior. Article in Journal/Newspaper Alaska Aleutian Islands Digital Commons University of South Florida (USF) Journal of Volcanology and Geothermal Research 151 4 365 381 |
institution |
Open Polar |
collection |
Digital Commons University of South Florida (USF) |
op_collection_id |
ftunisfloridatam |
language |
unknown |
topic |
Shishaldin volcano volcano seismology long-period earthquakes Earth Sciences |
spellingShingle |
Shishaldin volcano volcano seismology long-period earthquakes Earth Sciences Petersen, Tanja Caplan-Auerbach, Jacqueline McNutt, Stephen R. Sustained Long-Period Seismicity at Shishaldin Volcano, Alaska |
topic_facet |
Shishaldin volcano volcano seismology long-period earthquakes Earth Sciences |
description |
From September 1999 through April 2004, Shishaldin Volcano, Aleutian Islands, Alaska, exhibited a continuous and extremely high level of background seismicity. This activity consisted of many hundreds to thousands of long-period (LP; 1–2 Hz) earthquakes per day, recorded by a 6-station monitoring network around Shishaldin. The LP events originate beneath the summit at shallow depths (0–3 km). Volcano tectonic events and tremor have rarely been observed in the summit region. Such a high rate of LP events with no eruption suggests that a steady state process has been occurring ever since Shishaldin last erupted in April–May 1999. Following the eruption, the only other signs of volcanic unrest have been occasional weak thermal anomalies and an omnipresent puffing volcanic plume. The LP waveforms are nearly identical for time spans of days to months, but vary over longer time scales. The observations imply that the spatially close source processes are repeating, stable and non-destructive. Event sizes vary, but the rate of occurrence remains roughly constant. The events range from magnitude ∼ 0.1 to 1.8, with most events having magnitudes < 1.0. The observations suggest that the conduit system is open and capable of releasing a large amount of energy, approximately equivalent to at least one magnitude 1.8–2.6 earthquake per day. The rate of observed puffs (1 per minute) in the steam plume is similar to the typical seismic rates, suggesting that the LP events are directly related to degassing processes. However, the source mechanism, capable of producing one LP event about every 0.5–5 min, is still poorly understood. Shishaldin's seismicity is unusual in its sustained high rate of LP events without accompanying eruptive activity. Every indication is that the high rate of seismicity will continue without reflecting a hazardous state. Sealing of the conduit and/or change in gas flux, however, would be expected to change Shishaldin's behavior. |
format |
Article in Journal/Newspaper |
author |
Petersen, Tanja Caplan-Auerbach, Jacqueline McNutt, Stephen R. |
author_facet |
Petersen, Tanja Caplan-Auerbach, Jacqueline McNutt, Stephen R. |
author_sort |
Petersen, Tanja |
title |
Sustained Long-Period Seismicity at Shishaldin Volcano, Alaska |
title_short |
Sustained Long-Period Seismicity at Shishaldin Volcano, Alaska |
title_full |
Sustained Long-Period Seismicity at Shishaldin Volcano, Alaska |
title_fullStr |
Sustained Long-Period Seismicity at Shishaldin Volcano, Alaska |
title_full_unstemmed |
Sustained Long-Period Seismicity at Shishaldin Volcano, Alaska |
title_sort |
sustained long-period seismicity at shishaldin volcano, alaska |
publisher |
Digital Commons @ University of South Florida |
publishDate |
2006 |
url |
https://digitalcommons.usf.edu/geo_facpub/311 https://doi.org/10.1016/j.jvolgeores.2005.09.003 |
genre |
Alaska Aleutian Islands |
genre_facet |
Alaska Aleutian Islands |
op_source |
School of Geosciences Faculty and Staff Publications |
op_relation |
https://digitalcommons.usf.edu/geo_facpub/311 doi:10.1016/j.jvolgeores.2005.09.003 https://doi.org/10.1016/j.jvolgeores.2005.09.003 |
op_doi |
https://doi.org/10.1016/j.jvolgeores.2005.09.003 |
container_title |
Journal of Volcanology and Geothermal Research |
container_volume |
151 |
container_issue |
4 |
container_start_page |
365 |
op_container_end_page |
381 |
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1810485865848242176 |