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Trident seismicity information statement July 25, 2023 Notice: Planned Maintenance and Power Downs at Butrovich Data Center - Website Service Outage Alaska Volcano Observatory Sitka visit May 5-9, 2023 Get to know Makushin Volcano AVO Information Statement on Sheveluch Volcano, April 13, 2023

Currently active Mount Cerberus volcano now named Mount Young  33rd anniversary of Redoubt's 1989-1990 eruption Where did the Mystery Ash come from? Maybe YOU have the answer! No volcanic gases detected at Mt. Edgecumbe during recent survey. Mt. Edgecumbe gets a new monitoring station Mount Edgecumbe volcanic field changes from "dormant" to "active" -- what does that mean? Mount Edgecumbe Information Statement, April 22, 2022

Meet the Atka Volcanic Complex Resuspended ash from Aniakchak: August 2, 2021 Information Statement 90th Anniversary of the 1931 eruption of Aniakchak Volcano, Alaska Booming sounds from Veniaminof and their source AVO assists in multi-agency effort to monitor the Barry Arm Landslide in Prince William Sound AVO's 2020 Field Season

Alaska Volcano Observatory Expands Eruption Detection Capability in Cook Inlet The Alaska Volcano Observatory’s summer 2020 field work plans Update on AVO Operations during COVID-19

AVO announces extensive upgrades to volcano monitoring equipment during summer 2019 fieldwork New publication: Alaska Volcano Observatory geochemical database, version 2 New publication: On the eruption age and provenance of the Old Crow tephra New publication: Historically active volcanoes of Alaska v. 3

In the event of a federal government shutdown Tectonic earthquakes and Alaska volcanoes Volcanic Threat Assessment helps prioritize risk reduction efforts at U.S. volcanoes AVO hiring a software engineer at University of Alaska Fairbanks Geophysical Institute Happy 30th Birthday, AVO! New publication: Postglacial eruptive history and geochemistry of Semisopochnoi volcano, western Aleutian Islands, Alaska New publication: Geochemistry of some Quaternary lavas from the Aleutian Arc and Mt. Wrangell New publication: Geologic map of Chiginagak volcano New publication: Major-element glass compositions of tephra from the circa 3.6 ka eruption of Aniakchak volcano, Alaska Peninsula, Alaska New publication: The 2014 eruptions of Pavlof Volcano, Alaska New publication: Historically active volcanoes of Alaska reference deck, v.2

Bogoslof Volcano, Alaska: ongoing eruption through the Bering Sea Thank you Unalaska! Bogoslof Summary of Current Activity Bogoslof Summary of Current Activity, through 19 January 2017

AVO studies resuspended volcanic ash from the Katmai region to Kodiak Island, Alaska Citizen Science - Volcanic Ash Collection Workshop and Public Talk, Kodiak January 30, 2016 Fieldwork at Iliamna and Spurr New publication highlights the importance of ash scrubbing in the evaluation of hazards from explosive eruptions

Critical Volcano Monitoring Systems Returned to Operation in Alaska Resuspended Volcanic Ash from the Katmai Region to Kodiak Island Remobilized Katmai 1912 ash: community events and health hazard analysis Makushin 2015 Geology Blog Sixth Anniversary of the Redoubt 2009 Eruption Happy Anniversary, Shishaldin 1967 and 2014!

New Publication on Aniakchak Volcano Available Online 25th Anniversary of the 1989-90 Eruption of Redoubt Volcano AVO geochemical database now available AVO Scientists Discuss Cook Inlet Volcanoes on Frontier Scientists TV Series Announcing new monitoring equipment for Cleveland volcano 22nd anniversary of Crater Peak (Mt Spurr) June 27 eruption Revised Alaska Interagency Operating Plan for Volcanic Ash Episodes Anniversary of Aniakchak 1931 eruption! April 19th - anniversary of Shishaldin 1999 and Pavlof 1986! Ground-coupled airwaves and explosion signals at Shishaldin 5th anniversary of the Redoubt 2009 eruption Loss of Critical Volcano Monitoring Information in Alaska NEW VOLCANO NUMBERING SYSTEM IMPLEMENTED Loss of Critical Volcano Monitoring Information in Alaska Report released: Geochemical investigations of the hydrothermal system on Akutan Island, July 2012

24th Anniversary of the 1989-90 eruption of Redoubt Volcano Veterans Day slideshow Call for images from active and retired service members! AVO operations during lapse of federal government appropriations New Tool for Reporting Alaska Volcanic Ash Fall Allows Residents to Assist Scientific Monitoring 25 years monitoring Alaska volcanoes - press release

AVO slideshow for Veterans Day Large ash eruptions: when volcanoes reshape valleys -- free public lecture Father Hubbard and the history of exploration in the Valley of Ten Thousand Smokes - free lecture Remote sensing and volcanoes - free public lecture The Great Eruption of 1912 - free public lecture Infrasound Detection of Volcanic Explosions Archaeology of Katmai area and the impact of past eruptions - free public lecture Historical Photography of the Great 1912 Eruption - free public lecture Catastrophic Eruptions and People -- free public lecture Eruption of an Island Volcano: Kasatochi, 2008 -- free public lecture Exploring the Plumbing System of Katmai Volcanoes Exploration of Katmai and the Valley of Ten Thousand Smokes - free public lecture Commemorative presentation in Kodiak: Be Prepared! Earthquakes Below Alaskan Volcanoes - free public lecture DisaStory - A Day of Oral History 1912 Katmai Eruption Children's Program Monitoring Alaska's Volcanoes - free public lecture Landmark volcano study: Katmai Centennial Perspectives free download Special activities on AVO's website for 1912 centennial Alaska Park Science - Volcanoes of Katmai and the Alaska Peninsula AVO at the Alaska Aviation Trade Show and Conference May 5-6 The Great Katmai Eruption of 1912 - a free lecture in Anchorage: April 24, 2012 The Great Katmai Eruption of 1912: A Century of Research Tracks Progress in Volcano Science April 25 -- The Novarupta - Katmai 1912 eruption: a free lecture in Fairbanks by Judy Fierstein Summer lecture series on Alaskan volcanism Poster contest celebrates anniversary of Katmai eruption! Mark your calendar: April 24 public lecture on the great Novarupta-Katmai eruption of 1912 An important volcanic anniversary in Alaska! PUBLISHED: The 2009 Eruption of Redoubt Volcano, Alaska

2011 Alaska Interagency Operating Plan for Volcanic Ash Episodes now available How does Cleveland's lava dome compare to Redoubt's 2009 lava dome? Alaska Volcanoes Guidebook for Teachers

New Fact Sheet on Kasatochi How big is the 2009 Redoubt lava dome?

New map: Historically active volcanoes of Alaska Steaming at Augustine Sarychev Volcano: Active Volcanoes of the Kurile Islands Footage of Alaska's Redoubt Volcano taken on Monday, March 23, 2009. Pre-eruption footage of Redoubt Volcano, Saturday, March 20, 2009 Redoubt Volcano B-Roll Footage

Kasatochi 2008 eruption summary 6th Biennial Workshop on Subduction Processes emphasizing the Kurile-Kamchatka-Aleutian Arcs Geophysical Institute, University of Alaska, Fairbanks, Alaska Chiginagak volcano's acid crater-lake continues to supply acidic, metal-laden water to salmon spawning habitat on the Alaska Peninsula ALASKA VOLCANOES - TEACHER ACTIVITY GUIDEBOOK & KIT 20 years of AVO Viewing earthquake information for Alaska volcanoes

Pavlof webcam added Activity at Pavlof volcano Pavlof thermal anomaly AVO Scientists present at U.S. Department of Education Teacher-to-Teacher Workshop Cleveland webcam available Activity at Cleveland volcano Cleveland satellite images Sheveluch Eruption U.S. Geological Survey's alert notification system for volcanic activity KVERT Volcanic Warnings Ceased

New alert system for volcanic activity Three new webcams added AGU presentations requested New webcam available
Trident seismicity information statement July 25, 2023
Posted: July 25, 2023
This Information Statement provides an update on the volcanic unrest at Trident Volcano and the broader Katmai volcanic cluster.

Map showing location of Mount Katmai, Trident Volcano, Mount Mageik, Mount Martin, Novarupta, and earthquakes located July 21, 2022 - July 21, 2023.

• The unrest detected over the past five months is a result of magma intrusion beneath Trident Volcano.
• The elevated earthquake rate is also observed at neighboring volcanoes of the Katmai volcanic cluster, including Katmai, Martin, Mageik and the Novarupta vent.
• Some magma intrusions do not result in eruptions, and sometimes the unrest can persist for months or years prior to an eruption.
• If an eruption were to occur, the primary hazard would be from volcanic ashfall and drifting ash clouds, which could disrupt air and marine travel and impact local communities and infrastructure.
• The Alaska Volcano Observatory (AVO) continues to monitor the volcanoes of the Katmai volcanic cluster and will issue further updates as needed.

Current Observations

Rates of earthquakes
Earthquake activity at Trident Volcano has been elevated since August 2022 but has waxed and waned. The initial activity consisted of an unusual series of earthquakes beneath Trident Volcano that progressively migrated over four days from around 16 mi (25 km) below sea level to shallow depths of about 3 mi (5 km) below sea level. In response to this behavior, AVO raised the Volcano Alert Level and Aviation Color Code to ADVISORY/YELLOW on September 29, 2022. After a decrease in seismicity, AVO lowered the Alert Level and Aviation Color Code to GREEN/NORMAL on October 19, 2022.
In November 2022, activity again escalated and consisted of shallow earthquakes less than 5 mi (8 km) below sea level. Most quakes were less than magnitude 1, but dozens of magnitude 2 and 3 earthquakes have occurred. The largest earthquake so far reached a magnitude near 4 on November 20, 2022. The earthquake rate averaged between 10 to 20 daily earthquakes, occasionally reaching rates several times higher. This level of seismicity persisted into February 2023, prompting AVO to raise the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY on February 22, 2023.

Low-frequency earthquakes under Trident
In May 2023, AVO began detecting a marked increase in low-frequency earthquakes—in addition to regular earthquakes—at shallow and deep levels in the region between Trident and Novarupta, which lies 3 mi (5 km) to the northwest. These types of earthquakes often indicate the movement of magma or magmatic fluids within the Earth’s crust. The shallow, low-frequency events occur about 2.5 mi (4 km) north of Trident Volcano at the same depths as the regular earthquakes, around 3 mi (5 km) below sea level. The deep, low-frequency events span a broader area between Trident and Novarupta and occur 18.5 to 22 mi (30 to 35 km) below sea level. These deep low-frequency earthquakes are often accompanied by longer-duration bursts of continuous tremor, indicating deep fluid movement.

Other monitoring data
Ground uplift at Trident Volcano has also been detected in satellite radar data. Snow cover prohibits winter observations, which limits our ability to provide precise timing, but data from June 3, 2023, indicates that about 2 in (5 cm) of ground uplift has occurred since October 6, 2022. Uplift is most significant on the volcano’s south flank.
There have been no visual changes to the ground surface or hydrology. No gas emissions or temperature changes have been observed.

The presence of regular earthquakes, tremor, low-frequency earthquakes, and ground uplift indicates that magma has moved upwards beneath Trident Volcano. Migration of magma beneath the volcano increases the likelihood of an eruption. A stress increase in the Earth's crust caused by magma intrusion and related uplift is likely causing earthquakes.
Intrusions of new magma under volcanoes only sometimes result in volcanic eruptions. The ground uplift and earthquake activity at Trident Volcano may cease with no eruption. Similar episodes of unrest at other volcanoes worldwide end in eruptions about half the time. Unrest in volcanic systems like Trident sometimes lasts many months or years. Unrest could wax and wane, and if an eruption were to occur, it could be after months or years.
Specific types of unrest usually precede eruptive activity allowing AVO to provide advance warning. As magma gets closer to the Earth’s surface, changes in the ground uplift pattern, increased earthquake activity, increased ground surface temperatures, and possible gas emissions would be likely.
Unlike many active volcanoes, which consist of a large cone formed from repeated eruptions from a single vent, Trident eruptions tend to issue from new vents and form individual cones or domes. A new vent was formed during the most recent Trident eruption from 1953 to 1974. Therefore, if an eruption occurs, it is uncertain exactly where the vent would be, though monitoring data will likely help pinpoint the site as magma rises closer to the Earth’s surface.

Seismic activity at nearby volcanoes
Earthquakes are typically located in three regions within the Katmai volcanic cluster: Trident and Novarupta volcanoes, Mount Katmai to the northeast, and Martin and Mageik volcanoes to the southwest. Coincident with the unrest at Trident, earthquakes have also increased beneath Martin and Mageik volcanoes. However, the initial sequence of deep earthquakes and continued episodes of low-frequency earthquakes and tremor are concentrated beneath Trident. The increased seismicity observed at Martin and Mageik volcanoes may be a secondary effect due to magma movement beneath Trident Volcano.

Potential hazards
If an eruption were to occur at Trident, the primary hazard would be from volcanic ashfall and drifting ash clouds, which could disrupt air and marine travel and impact local communities and infrastructure. The areas impacted by ashfall and drifting ash clouds would depend on the wind direction during the eruption.
Areas closer to the eruption site, especially near the edifice, could experience additional hazardous phenomena, such as ballistics (rocks forcibly ejected from the vent) or pyroclastic flows. Pyroclastic flows and hot ash could also fall on or erode snow-covered slopes, leading to volcanic mudflows or lahars in the volcano's drainages.
For a full description of volcanic hazards associated with Trident Volcano, please see the following report: Trident Volcano preliminary hazard assessment

Current monitoring
AVO monitors Trident Volcano and other volcanoes in the Katmai volcanic cluster with a local network of seismometers, infrasound sensors, a webcam, remote sensing data, and regional infrasound and lightning networks.
• To view information about Trident Volcano: Trident Volcano activity page
• Web camera that shows Trident: Trident Volcano webcam
• Location map showing Trident and the Katmai volcanic cluster: Trident Volcano location map

Trident is one of the Katmai group of volcanoes located within Katmai National Park and Preserve on the Alaska Peninsula. Trident consists of a complex of four cones and numerous lava domes, all andesite and dacite in composition, that reach as high as 6,115 ft (1.9 km) above sea level. An eruption beginning in 1953 constructed the newest cone, Southwest Trident, and four lava flows on the flank of the older complex. This eruption continued through 1974 and produced ash (an initial plume rose to 30,000 ft or 9.1 km above sea level), bombs, and lava at various times. Fumaroles remain active on the summit of Southwest Trident and on the southeast flank of the oldest, central cone. Trident is located 92 miles (148 km) southeast of King Salmon and 273 miles (440 km) southwest of Anchorage.
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URL: avo.alaska.edu/news.php
Page modified: December 2, 2016 10:12
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