Innovation, vigilance keys to first 25 years of Alaskan observatory

Earlier this year, the Alaska Volcano Observatory (AVO) completed its first 25 years of operation. It received widespread acknowledgement for its crucial role in warning of eruptions and advancing scientific understanding of the hazards posed by Alaska volcanoes.

It was an immensely ambitious and challenging 25 years, marked by more than 70 different episodes of eruption and unrest from nearly 30 different Alaskan volcanoes and the most expansive volcano-monitoring effort in U.S. history.

The signature event that shaped the observatory’s mission more than any other was the 1989-90 eruption of Redoubt Volcano, located 110 miles southwest of Anchorage. One of the eruption’s ash cloud nearly brought down a Boeing 747 jetliner carrying 244 people as it descended into Anchorage.

The plane flew through an ash cloud erupted by the volcano and quickly lost power to all four engines. After a steep and terrifying descent to within 4,000 feet of the ground, the pilots were able to restart the engines and land safely.

This encounter between ash and aircraft soon galvanized support for an aggressive effort to scale-up monitoring of Alaska’s historically active and potentially active volcanoes by increasing the number of ground-based instruments and the use of satellite resources.

AVO increased the number of Alaskan volcanoes monitored with seismic instruments from 4 in 1995 to 29 in early 2013, a remarkable feat, given the notorious weather in Alaska and the great length of the volcanic chain that stretches from Cook Inlet to the Aleutian Islands — more than 1,500 miles.

Support for AVO was also focused on developing capability and expertise to utilize satellite resources to (1) detect signs of unrest; (2) identify and track ash clouds downwind from an erupting volcano; and (3) advance computer models used to forecast the downwind path of ash.

With so many active and erupting volcanoes to monitor, AVO constantly strived to improve and rapidly disseminate volcano activity notifications and ash-cloud information to the aviation industry and to the public in collaboration with the Federal Aviation Authority and National Weather Service.

During the 1989-90 Redoubt eruption, AVO implemented a novel four-level color scheme for communicating the immediate status or hazard level of the volcano in a simple, consistent manner. Green, for example, meant the volcano was quiet. Yellow was for slightly elevated activity but no eruption. Orange and red represented eruptions that generated ash columns to increasing altitudes.

The color scheme was eventually endorsed by the International Civil Aviation Organization for use by volcano observatories worldwide. It served as the basis for the new, standardized alert-notification systems used by all U.S. volcano observatories beginning in 2006 (see fact sheet,

The standardized alert system enabled creation of the Volcano Notification Service (VNS) that sends emails to subscribers about volcanic activity at monitored U.S. volcanoes. Subscribers can customize requests to receive notifications only for certain volcanoes, or range of volcanoes, or by notification type (to subscribe, visit There are now nearly 4,500 subscribers since it was launched for the public in 2012.

This year, AVO launched a new web tool — Is Ash Falling? — to help improve the collection of ash-fall information in near real-time. The online form allows people to report on the timing and location of ash fall and the thickness of the resulting deposit. Users of the AVO website ( are directed to the “Is Ash Falling?” form on the activity page of an erupting or restless volcano. where they can also view a map of ash-fall reports.

These firsthand accounts of ash-fall information help scientists better identify the path of developing ash clouds, quantify ash deposition, and improve warning messages about ash. The accounts are ground-truthing crucial for continually improving interpretation of satellite imagery and new computer models used to forecast when and where ash will go and what areas it will affect.

Soon after its 25th anniversary in April, eruptions of two of Alaska’s most active volcanoes — Pavlof and Veniaminof — generated small eruptions and ash clouds. Volcano monitoring requires the vigilance of AVO, and now more than ever, the public.


activity update

A lava lake within the Halema‘uma‘u Overlook vent produced nighttime glow that was visible via HVO’s webcam during the past week. Two deflation-inflation cycles (DI events) occurred during the week, as of Thursday, and the lava lake level fell, then correspondingly rose again during each cycle.

On Kilauea’s East Rift Zone, a breakout from the Peace Day tube above the pali was probably still active on October 29, based on infrared satellite imagery. The Kahauale‘a 2 flow, fed from a spatter cone on the northeast edge of the Pu‘u ‘O‘o crater, continues to advance slowly across old flows and into the forest. Its tip was 3.6 miles northeast of Pu‘u ‘O‘o when last mapped on Oct. 21.

No earthquakes were reported felt on the Island of Hawaii during the past week. Visit the HVO website ( for Volcano Awareness Month details and Kilauea, Mauna Loa and Hualālai activity updates, recent volcano photos, recent earthquakes, and more; call 967-8862 for a Kilauea summary; email questions to

Volcano Watch ( is a weekly article and activity update written by scientists at the U.S. Geological Survey`s Hawaiian Volcano Observatory.


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