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Cheryl E. Cameron

Publications and source records attributed to Cheryl E. Cameron.

18 recordsLinked to original sources
USGS2023

2019 Volcanic activity in Alaska—Summary of events and response of the Alaska Volcano Observatory

The Alaska Volcano Observatory responded to eruptions, volcanic unrest or suspected unrest, increased seismicity, and other significant activity at 17 volcanic centers in Alaska in 2019. The most notable volcanic activity was an eruption of Shishaldin Volcano, featuring eruptive activity that produced lava flows, lahars, and ash. Weak explosive activity also took place at Great Sitkin Volcano and Semisopochnoi Island. Mount Cleveland had one small ash-producing eruption followed by dome growth in early January but was quiet thereafter, and flank activity at Shrub mud volcano produced new mud deposits. Other activity documented in 2019 consists of declining unrest at Mount Veniaminof after its 2018 eruption; large ice and rock avalanches at Iliamna Volcano and Mount Spurr; anomalous seismicity and an increase in degassing at Pavlof Volcano; long-term inflation at Westdahl volcano, Akutan Volcano, and Mount Okmok; steam plumes and anomalous seismicity at Makushin Volcano; elevated seismicity at Mount Martin; and resuspended ash from the 1912 Novarupta-Katmai eruption deposits.

Alaska↗
USGS2023

2018 Volcanic activity in Alaska—Summary of events and response of the Alaska Volcano Observatory

The Alaska Volcano Observatory responded to eruptions, considerable and minor volcanic unrest, and seismic events at 15 volcanic centers in Alaska during 2018. The most notable volcanic activity came from Mount Cleveland, which had continuing intermittent dome growth and ash eruptions, and Mount Veniaminof, Great Sitkin Volcano, and Semisopochnoi Island, the three of which had minor eruptions. This report also documents landslides at Iliamna Volcano; resuspended ash from the 1912 Novarupta-Katmai eruption; anomalous seismicity and heightened degassing at Pavlof Volcano; seismic unrest at Shishaldin Volcano; long-term inflation at Westdahl volcano, Akutan Volcano, and Mount Okmok; steam plumes, anomalous seismicity, and anomalous gas measurements at Makushin Volcano; elevated seismicity at Mount Gareloi; seismic signals possibly related to icequakes at Mount Spurr; and new mud flows at Shrub mud volcano.

Alaska↗
USGS2020

2017 Volcanic activity in Alaska—Summary of events and response of the Alaska Volcano Observatory

The Alaska Volcano Observatory responded to eruptions, significant and minor volcanic unrest, and seismic events at 16 volcanic centers in Alaska during 2017. The most notable volcanic activity consisted of a major eruption at Bogoslof Island, continuing intermittent dome growth and ash eruptions from Mount Cleveland, the end of the Pavlof Volcano eruption, volcanic unrest at Shishaldin Volcano, and significant earthquake activity at Tanaga and Great Sitkin Islands. This report also documents reports of degassing at Redoubt Volcano, Makushin Volcano, Mount Gareloi, and Kiska Volcano, anomalous seismicity at Mount Spurr, Augustine Volcano, Akutan Peak, and Makushin Volcano, landslides at Iliamna Volcano, resuspended ash from the 1912 Novarupta-Katmai eruption, and continuing inflation at Okmok Caldera.

Alaska↗
USGS2020

2016 Volcanic activity in Alaska—Summary of events and response of the Alaska Volcano Observatory

The Alaska Volcano Observatory responded to eruptions, volcanic unrest or suspected unrest, and seismic events at 15 volcanic centers in Alaska during 2016. The most notable volcanic activity consisted of eruptions at Pavlof and Bogoslof volcanoes. Both eruptions produced significant ash clouds that affected regional air travel. Mount Cleveland continued a pattern of dome growth followed by explosion, producing very short-lived ash clouds. An eruptive period at Shishaldin Volcano ended in 2016.

Alaska↗
USGS2020

Geology and eruptive history of Bogoslof volcano

Bogoslof volcano is a shallow submarine/subaerial volcano in the southern Bering Sea about 100 km west of the community of Dutch Harbor, Alaska. The subaerial parts of the volcano consist of two small islands, Bogoslof Island and Fire Island, that together have a total area of about 1.6 km 2 . Bogoslof was first depicted on a Russian map in 1772 and since then has been observed and visited occasionally. The volcano has had at least nine periods of eruptive activity since 1796 and all of its historical eruptions have been similar in style. Historical Bogoslof eruptions involved the effusion of basalt, trachybasalt, basaltic trachyandesite, and trachyandesite lava domes with above sea level relief of 100–200 m. Many of the eruptions are accompanied by the formation of tuff rings and ejection of ballistic particles. Historical observations suggest that eruption clouds are relatively ash-poor. Minor ash fallout has typically occurred within about 100 km of the volcano. Many of the historical eruptions began at vents that were below sea level, and thus, seawater has played an important role in the style of eruptive activity exhibited by the volcano. At times, eruptive activity has been characterized by Surtseyan style eruptions and magma interaction with wet vent-fill deposits. At other times, the eruptive style has been more magmatically driven and has resulted in the formation of pyroclastic flows and small ash clouds. Preliminary studies of the deposits produced during the 2016–2017 eruption indicate vertical sequences of coarse-grained, horizontally bedded pyroclastic flow and fall deposits with numerous blocks, bombs, and lapilli of dense juvenile and accidental lithic material. These deposits were emplaced by near-vent pyroclastic flows, surges, and explosions some of which originated from shallow, highly crystalline cryptodomes.

Bulletin of Volcanology↗
USGS2020

Major-oxide and trace-element geochemical data from rocks collected on Little Sitkin Island, from Little Sitkin Volcano, Alaska

During the 2005 summer field season, geologists Michelle Coombs, Christina Neal, and Jessica Larsen from the University of Alaska, Fairbanks and the U.S. Geological survey, Alaska Volcano Observatory (AVO) conducted fieldwork on Little Sitkin Island in the western Aleutians of Alaska. The primary purpose of the fieldwork was to install geophysical networks for volcano monitoring. As part of this effort, AVO geologists conducted reconnaissance fieldwork focused primarily on sample collection for geochemistry.

Alaska↗
USGS2018

Historical eruptions and hazards at Bogoslof volcano, Alaska

Bogoslof volcano is a submarine volcano in the southern Bering Sea (53.9272°N, 168.0344°W), located 100 kilometers (km) west of Dutch Harbor/Unalaska, and 40 km north of Umnak Island. The volcano has a relatively long history of scientific investigation and several of its historical eruptions have been documented during brief visits to the area since the late 1700s. The purpose of this report is to provide a modern volcanological perspective on past eruptions of Bogoslof and to readdress some of the eruptive phenomena described in historical documents and reports. We also present for the first time a brief analysis of the hazards posed by Bogoslof eruptions. While this report was being prepared, Bogoslof volcano was in an ongoing state of eruptive activity that began in mid-December 2016. Detectable eruptive activity ended in late August 2017 and the volcano has remained quiet since then. Because we have not yet visited Bogoslof Island and have only a few distal tephra samples from two eruptive events, we will not discuss in detail the 2016–17 eruptive sequence, but will provide some information for comparative purposes. When more detailed data has been collected, a more extensive review of the 2016–17 Bogoslof eruption should be the subject of future reports.

Alaska↗
USGS2018

Analysis of the Alaska Volcano Observatory’s response time to volcanic explosions-1989 to 2016

A major goal of volcano monitoring is the rapid identification of volcanic explosions and subsequent warning of associated hazards. Between 1988 and 2016 the Alaska Volcano Observatory (AVO) responded to at least 54 separate volcanic eruptions. During this period, AVO's monitoring program relied principally on seismic and satellite remote sensing data, supplemented with geodetic, gas, and visual observations to track volcanic unrest. In this study we focus on AVO's response time, or the time required for AVO to (1) identify seismic signals associated with large ash-producing volcanic explosions and (2) initiate public warnings. We restrict this analysis to volcanoes monitored by a local seismic network and explosive in character. We focus on the 1989–90 eruption of Redoubt Volcano (VEI 3), the 1992 eruption of Mount Spurr (VEI 4), the 1999 eruption of Shishaldin Volcano (VEI 3), the 2006 eruption of Augustine Volcano (VEI 3) and the 2016 eruption of Pavlof Volcano (VEI 2) as detailed records of the timing of formal warnings are preserved. These eruption sequences allow us to evaluate AVO's response time under a number of monitoring scenarios, including both expected (those with recognized precursory unrest) and surprise eruptions (those without identified precursory unrest) as well as individual and repetitive sequences of explosive events. Recorded response time ranges from ~1 to 86 min. The shorter response times (~1–13 min) were achieved during sequences of explosive events at Redoubt (1989–90), Spurr (1992) and Augustine (2006). The longer response times (31– 86 min) are recorded for unexpected or surprise explosions such as Spurr (August 18, 1992) and Pavlof (2016) and the only or first explosions in an eruptive sequence such as Shishaldin (1999) and Augustine (2006).

Alaska↗
USGS2017

The 2014 eruptions of Pavlof Volcano, Alaska

Pavlof Volcano is one of the most frequently active volcanoes in the Aleutian Island arc, having erupted more than 40 times since observations were first recorded in the early 1800s . The volcano is located on the Alaska Peninsula (lat 55.4173° N, long 161.8937° W), near Izembek National Wildlife Refuge. The towns and villages closest to the volcano are Cold Bay, Nelson Lagoon, Sand Point, and King Cove, which are all within 90 kilometers (km) of the volcano (fig. 1). Pavlof is a symmetrically shaped stratocone that is 2,518 meters (m) high, and has about 2,300 m of relief. The volcano supports a cover of glacial ice and perennial snow roughly 2 to 4 cubic kilometers (km 3 ) in volume, which is mantled by variable amounts of tephra fall, rockfall debris, and pyroclastic-flow deposits produced during historical eruptions. Typical Pavlof eruptions are characterized by moderate amounts of ash emission, lava fountaining, spatter-fed lava flows, explosions, and the accumulation of unstable mounds of spatter on the upper flanks of the volcano. The accumulation and subsequent collapse of spatter piles on the upper flanks of the volcano creates hot granular avalanches, which erode and melt snow and ice, and thereby generate watery debris-flow and hyperconcentrated-flow lahars. Seismic instruments were first installed on Pavlof Volcano in the early 1970s, and since then eruptive episodes have been better characterized and specific processes have been documented with greater certainty. The application of remote sensing techniques, including the use of infrasound data, has also aided the study of more recent eruptions. Although Pavlof Volcano is located in a remote part of Alaska, it is visible from Cold Bay, Sand Point, and Nelson Lagoon, making distal observations of eruptive activity possible, weather permitting. A busy air-travel corridor that is utilized by a numerous transcontinental and regional air carriers passes near Pavlof Volcano. The frequency of air travel across the region results in a relatively large number of airborne observations of eruptive activity. During the 2014 Pavlof eruptions, the Alaska Volcano Observatory received observations and photographs from pilots and local observers, which aided evaluation of the eruptive activity and the areas affected by eruptive products. This report outlines the chronology of events associated with the 2014 eruptive activity at Pavlof Volcano, provides documentation of the style and character of the eruptive episodes, and reports briefly on the eruptive products and impacts. The principal observations are described and portrayed on maps and photographs, and the 2014 eruptive activity is compared to historical eruptions.

Alaska↗
USGS2017

2015 Volcanic activity in Alaska—Summary of events and response of the Alaska Volcano Observatory

The Alaska Volcano Observatory (AVO) responded to eruptions, volcanic unrest or suspected unrest, and seismic events at 14 volcanic centers in Alaska during 2015. The most notable volcanic activity consisted of continuing intermittent ash eruptions from Cleveland and Shishaldin volcanoes in the Aleutian Islands. Two eruptive episodes, at Veniaminof and Pavlof, on the Alaska Peninsula ended in 2015. During 2015, AVO re-established the seismograph network at Aniakchak, installed six new broadband seismometers throughout the Aleutian Islands, and added a Multiple component Gas Analyzer System (MultiGAS) station on Augustine.

Alaska↗
USGS2017

2014 volcanic activity in Alaska: Summary of events and response of the Alaska Volcano Observatory

The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest or suspected unrest, and seismic events at 18 volcanic centers in Alaska during 2014. The most notable volcanic activity consisted of intermittent ash eruptions from long-active Cleveland and Shishaldin Volcanoes in the Aleutian Islands, and two eruptive episodes at Pavlof Volcano on the Alaska Peninsula. Semisopochnoi and Akutan volcanoes had seismic swarms, both likely the result of magmatic intrusion. The AVO also installed seismometers and infrasound instruments at Mount Cleveland during 2014.

Alaska↗
USGS2017

Geology of Kasatochi Volcano, Aleutian Islands, Alaska

Kasatochi is a small, isolated island volcano in the center of the Aleutian Island chain. It consists of a roughly circular cone ~3 km in diameter with a lake-filled central crater that is 1.2 km in diameter and extends from the highest point on the island to sea level. The earliest unit recognized is a thick series of mid-Pleistocene glaciovolcanic deposits consisting of autobrecciated lava, lahars, and volumetrically minor lava masses that we believe to have been emplaced underneath a regional ice cap. This unit is unconformably overlain by several massive Holocene lavas, above which lies a thick sequence of latest- Holocene pyroclastic deposits likely deposited during the crater-forming eruption. The 2008 eruption enlarged the preexisting crater, and produced pyroclastic density currents, surges, and fall that blanketed the entire island except for steep, seaward-facing cliffs on the flanks and the crater wall. 2008 deposits initially extended the shoreline seaward by up to 500 m. Kasatochi lava and scoria are porphyritic basalt, basaltic andesite, and andesite, all of which bear trace-element evidence for prolonged crustal residence and equilibration with an amphibole-rich gabbroic residue. Lavas from individual effusive eruptions have limited compositional range, whereas juvenile scoriae from explosive eruptions span the majority of the compositional range of the entire volcano. 2008 pyroclastic deposits contain texturally diverse amphibole gabbro clasts and smaller, less abundant, plagioclase-free pyroxenitic and peridotitic cumulate inclusions. We infer that the gabbroic inclusions are from the margins of regions of crustal magma storage and evolution and that equilibration with the amphibole plays an important role in the evolution of mafic and intermediate magmas.

Alaska↗
USGS2014

2012 volcanic activity in Alaska: Summary of events and response of the Alaska Volcano Observatory

The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest, or suspected unrest at 11 volcanic centers in Alaska during 2012. Of the two verified eruptions, one (Cleveland) was clearly magmatic and the other (Kanaga) was most likely a single phreatic explosion. Two other volcanoes had notable seismic swarms that probably were caused by magmatic intrusions (Iliamna and Little Sitkin). For each period of clear volcanic unrest, AVO staff increased monitoring vigilance as needed, reviewed eruptive histories of the volcanoes in question to help evaluate likely outcomes, and shared observations and interpretations with the public. 2012 also was the 100th anniversary of Alaska’s Katmai-Novarupta eruption of 1912, the largest eruption on Earth in the 20th century and one of the most important volcanic eruptions in modern times. AVO marked this occasion with several public events.

Alaska↗
USGS2013

Andesites of the 2009 eruption of Redoubt Volcano, Alaska

Crystal-rich andesites that erupted from Redoubt Volcano in 2009 range from 57.5 to 62.5 wt.% SiO 2 and have phenocryst and phenocryst-melt relations consistent with staging in the upper crust. Early explosive products are low-silica andesites (LSA, < 58 wt.% SiO 2 ) that ascended from deeper crustal levels during or before the 6 months of precursory activity, but a broad subsequent succession to more evolved and cooler products, and predominantly effusive dome growth, are interpreted to result from progressive mobilization and mixing with differentiated magmas tapped from pre-2009 Redoubt intrusions at ~ 3–6 km depth. Initial explosions on March 23–28 ejected predominantly LSA with a uniform phenocryst assemblage of high-Al amphibole, ~ An 70 plagioclase, ortho- and clinopyroxene, FeTi oxides (890 to 960 °C), and traces of magmatic sulfide. Melt in the dominant microlite-poor LSA was compositionally uniform dacite (67–68 wt.% SiO 2 ) but ranged to rhyolite with greater microlite growth. Minor amounts of intermediate- to high-silica andesite (ISA, HSA; 59–62.5 wt.% SiO 2 ) also erupted during the early explosions and most carried rhyolitic melt (72–74 wt.% SiO 2 ). A lava dome grew following the initial tephra-producing events but was destroyed by an explosion on April 4. Ejecta from the April 4 explosion consists entirely of ISA and HSA, as does a subsequent lava dome that grew April 4–July 1; LSA was absent. Andesites from the April 4 event and from the final dome had pre-eruptive temperatures of 725–840 °C (FeTi oxides) and highly evolved matrix liquids (77–80 wt.% SiO 2 ), including in rare microlite-free pyroclasts. ISA has mixed populations of phenocrysts suggesting it is a hybrid between HSA and LSA. The last lavas from the 2009 eruption, effused May 1–July 1, are distinctly depleted in P 2 O 5 , consistent with low temperatures and high degrees of crystallization including apatite. Plagioclase–melt hygrometry and comparison to phase equilibrium experiments are consistent with pre-eruptive storage of all three magma types at 100–160 MPa (4–6 km depth), if they were close to H 2 O-saturation, coincident with the locus of shallow syn-eruptive seismicity. Deeper storage would be indicated if the magmas were CO 2 -rich. Relatively coarse-grained clinopyroxene-rich reaction rims on many LSA amphibole phenocrysts may result from slow ascent to, or storage at, depths shallow enough for the onset of appreciable H 2 O exsolution, consistent with pre-eruptive staging in the uppermost crust. We interpret that the 2009 LSA ascended from depth during the 8 or more months prior to the first eruption, but that the magma stalled and accumulated in the upper crust where its phenocryst rim and melt compositions were established. Ascent of LSA through stagnant mushy intrusions residual from earlier Redoubt activity mobilized differentiated magma pockets and interstitial liquids represented by HSA, and as LSA–HSA hybrids represented by ISA, that fed the subsequently erupted lava domes.

Alaska↗
USGS2011

2008 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory

The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, and volcanic unrest or suspected unrest at seven separate volcanic centers in Alaska during 2008. Significant explosive eruptions at Okmok and Kasatochi Volcanoes in July and August dominated Observatory operations in the summer and autumn. AVO maintained 24-hour staffing at the Anchorage facility from July 12 through August 28. Minor eruptive activity continued at Veniaminof and Cleveland Volcanoes. Observed volcanic unrest at Cook Inlet's Redoubt Volcano presaged a significant eruption in the spring of 2009. AVO staff also participated in hazard communication regarding eruptions or unrest at nine volcanoes in Russia as part of a collaborative role in the Kamchatka and Sakhalin Volcanic Eruption Response Teams.

Alaska, Kamchatka↗
USGS2010

Public outreach and communications of the Alaska Volcano Observatory during the 2005-2006 eruption of Augustine Volcano: Chapter 27 in The 2006 eruption of Augustine Volcano, Alaska

The 2005-6 eruption of Augustine Volcano in the Cook Inlet region, Alaska, greatly increased public desire for volcano hazard information, as this eruption was the most significant in Cook Inlet since 1992. In response to this heightened concern, the Alaska Volcano Observatory (AVO) increased ongoing efforts to deliver specific eruption-focused information to communities nearest to the volcano, created a public communications strategy to assist staff with managing requests, and used the recently upgraded AVO Web site as a primary information-delivery path. During the eruption, AVO responded to a minimum of ~1,700 individual requests for information from the media, the public, and other organizations with responsibilities associated with volcanic activity in Alaska; requests were received both as phone calls to the observatory and e-mail stemming from the AVO Web site. Staff also delivered approximately two dozen Augustine-specific presentations and gave nearly three dozen tours of the AVO Anchorage Operations Center in Anchorage. This intensity of public interaction was markedly higher than during noneruptive periods. During the Augustine unrest and eruption, AVO also refined its internal communication procedures, instituted and maintained up-to-date and concise talking points concerning the most recent and relevant volcanic activity and hazards, and created a media management plan to assist staff in working with members of the media. These items aided staff in maintaining a consistent message concerning the eruption, potential hazards, and our response activities. The AVO Web site, with its accompanying database, is the backbone of AVO's external and internal communications. This was the first Cook Inlet volcanic eruption with a public expectation of real-time access to data, updates, and hazards information over the Internet. In March 2005, AVO improved the Web site from individual static pages to a dynamic, database-driven site. This new system provided quick and straightforward access to the latest information for (1) staff within the observatory, (2) emergency managers from State and local governments and organizations, (3) the media, and (4) the public. From mid-December 2005 through April 2006, the AVO Web site served more than 45 million Web pages and about 5.5 terabytes of data.

Alaska↗