Akutan Peak

Elevation:4275 ft Latitude:54.13308° NLongitude:165.98555° W

Official Name: Akutan PeakType: Stratovolcano with calderaLatest Activity: 12.18.1992 Seismically Monitored:Yes

Akutan is one of the most volcanically active islands in the eastern Aleutian arc.

TYPE:

From Miller and others

(1998): “Akutan volcano is

a composite stratovolcano

with a circular summit cal-

dera about 2 km across and

60 to 365 m deep(Byers and

Barth, 1953; Romick and

others, 1990; Motyka and

others, 1981) and an active

intracaldera cinder cone. The

caldera rim reaches a max-

imum altitude of 1303 m at

Akutan Peak, the remnant

of a pre-caldera cone now

filled with a lava plug. The

caldera is breached to the

north. Caldera subsidence

accompanied or followed

eruptions from a series of

rim vents. The vestige of a

larger caldera, of probable

late Pleistocene age and at

least in part older than the

cone of Akutan Peak, ex-

tends 1.5 km southwest of

Akutan Peak and is termi-

nated to the north by the

younger caldera. Small gla-

ciers fill the older crater and

lie within the southwest and

southeast margins of the

younger caldera.

“The active intracaldera cin-

der cone is over 200 m high,

about 1 km in diameter, and

located in the northeast quar-

ter of the caldera. Three small

sulfur-lined craters occupy its

summit and several fumarole

zones are present along its

south and southwest flank

(Byers and Barth, 1953). A

crescent-shaped lake along

the inner southwest rim of

the caldera and a hot and

slightly acidic lake along the

northern caldera wall were

noted by Byers and Barth in

1948 but Motyka and others

(1981) speculate that these

lakes may have been obliter-

ated by more recent activity.

Both lakes drained to the

north through a gap in the

caldera wall.

DefintionsCaldera

Pleistocene Age

A caldera is a large, usually circular depression at the summit of a volcano formed when magma is with-drawn or erupted from a shallow underground magma reservoir. The removal of large volumes of magma may result in loss of structural support for the overlying rock, thereby leading to collapse of the ground and formation of a large depression. Calderas are different from craters, which are smaller, circular depressions created primarily by explosive excavation of rock during eruptions.

The most recent episode of glaciation, the Pleisto-cene epoch, is commonly referred to as the Ice Age and began approximately 1.6 million years ago. During that time there were a number of advanc-es and retreats of the glaciers, which are termed glacial and interglacial stages, respectively. The glaciers of Greenland and Antarctica are remnants of the last glacial advance.

“The lava flows and pyro-

clastic deposits of Akutan

volcano are no older than

Pleistocene as Romick and

others (1990) report ages of

1.1 +/- 0.1 to 1.8 +/- 0.8 Ma

for the oldest of these rocks.

The caldera-forming erup-

tion occurred about 5,200

yBP (Reeder, 1983) and was

the source of small volume

andesitic pyroclastic-flow

deposits in valleys on the

north, south, and east sides

of the volcano (Miller and

Smith, 1987; Romick and

others, 1990). Young basal-

tic lava flows, some of which

were erupted in 1929, cover

the caldera floor south and

north of the cinder cone

and extend several hundred

m downslope through the

crater rim gap. Flows ex-

truded in 1947 blanket the

central portion of the north-

west end of the island at

Lava Point, where about 4

square kilometers of jagged

aa basalt occurs adjacent to

several cinder cones. The

entire island is mantled by

an ash layer that thickens

toward Akutan Peak; land-

slide and mud flow depos-

its . have concentrated this

ejecta in the valleys north

and northeast of the caldera

and a maximum fill depth

of 7 m occurs at Wooly Cove

(Finch, 1935).

“Active hot springs occur

northeast of the caldera at

the head of Hot Springs

Bay valley and along the

shore of Hot Springs Bay;

Byers and Barth (1953) and

Motyka and others (1990)

recorded temperatures

between 67 and 84 degrees

C and a pH range of 6.6

to 7. Surface waters of the

hot caldera lake were 50

degrees C with a pH of 5.0

and steam issuing from

fumaroles along the cinder

cone base averaged 96 de-

grees C (Finch, 1935).”

Recent eruptions produced

only small amounts of

fine volcanic ash that fell

primarily on the upper

flanks of the volcano. Small

amounts of ash fell on the

Akutan Harbor area during

eruptions in 1911, 1948,

1987, and 1989. Plumes

of volcanic ash are the

primary hazard associated

with eruptions of Akutan

Volcano and are a major

hazard to all aircraft using

the airfield at Dutch Har-

bor or approaching Akutan

Island. Eruptions similar to

historical Akutan eruptions

should be anticipated in the

future. Although unlikely,

eruptions larger than those

of historical time could gen-

erate significant amounts

of volcanic ash, fallout,

pyroclastic flows, and lahars

that would be hazardous

to life and property on all

sectors of the volcano and

other parts of the island,

but especially in the major

valleys that head on the

volcano flanks. During a

large eruption, an ash cloud

could be produced that may

be hazardous to aircraft us-

ing the airfield at Cold Bay

and the airspace downwind

from the volcano. In the

event of a large eruption,

volcanic ash fallout could be

relatively thick over parts of

Akutan Island and volcanic

bombs could strike areas

more than 10 kilometers

from the volcano.

A lava flow in 1978 traveled

through a narrow breach

in the north caldera rim to

within 2 km of the coast.

A small lake occupies part

of the caldera floor. Two

volcanic centers are located

on the NW flank: Lava Peak

is of Pleistocene age; and,

a cinder cone lower on the

flank which produced a lava

flow in 1852 that extended

the shoreline of the island

and forms Lava Point. An

older, mostly buried caldera

seems to have formed in

Pleistocene or Holocene

time, while the current

caldera formed in a VEI-5

eruption c. 340 AD. The

volcano erupted most re-

cently in 1992, but there is

still fumarolic activity at the

base of Lava Point and there

are hot springs North-East

of the caldera.

Eruptions and Activity

1996 Earthquakes

Intense seismicity was felt by Akutan residents on

the evening of 10-11 March 1996. The swarm of 80

earthquakes lasted for 11 hours. The largest earth-

quake was magnitude 5.1. On 13th March, felt-earth-

quakes began occurring at a rate of greater than 1/

minute. The largest earthquakes were felt as far away

as Dutch Harbor/Unalaska 50 km SW of Akutan.

On 14th March, earthquakes were strong enough

to ring the bell in the Russian Orthodox Church,

during a second swarm of 120 earthquakes. In total,

more than 3000 earthquakes occurred beneath the

island. Extensive ground cracking resulted, but no

eruption occurred.

1992 EruptionsSmall steam and ash eruption occurred at Akutan

volcano in April and December 1992.

1991 EruptionsSummit ash emissions began in September, with a

plume to 4500 m altitude. Ashfall was reporded at

Akutan village.

1990 EruptionsSmall ash eruptions were reported in September

and October. Maximum height of plumes were

1500 m above the summit.

1989 EruptionsIn March 1989 an air shock wave was felt by a

pilot flying over the western shore of Akutan vol-

cano. Black ash was emitted to a height of 2,300 m

above the volcano.

1988 EruptionsAsh emissions occurred at Akutan volcano be-

tween March and June 1988. Most observations

were by pilots.

1987 EruptionsOn 22nd June 1987 a summit glow was seen by a

fisherman in the Bering Sea. Two days later, a pilot

reported ash emissions to 1300 m altitude from a

large cinder cone in the summit crater.

1986 EruptionsIn June, numerous ash emissions to an altitude of

3.5 km were visible from Akutan village.

1980 EruptionsOn the 3rd July a recent lava flow that had moved

through a breach in the NNW caldera wall was

observed.

1978 EruptionIn 1978 lava flowed through a gap in the calde-

ra and came within 1 km of the sea in the north.

Strombolian eruptions occurred at the summit.

1977 EruptionsEruptions began in May, with light brown ash

emissions every 15 minutes. Incandescence was

noted in some eruptions.

1974 EruptionsIn February, ash was emitted hundreds of feet into

the air, and lava flowed down the flank.

1973 EruptionsAkutan volcano erupted ash and steam for several

months, with the mountain snow-free.

1946-48 Eruptions 1946-48 EruptionsLava flows occurred at the volcano caldera.

1924 EruptionA lava flow occurred on the floor of the caldera.

Eruptions in the 1850’sA cinder cone and two lava flows were erupted north of Lava Peak. The lava flows formed two lobes which flowed into the sea, forming Lava Point.

Other Eruptions1912, 1911, 1908, 1907, 1896, 1892, 1887, 1883, 1867, 1865, 1852, 1848, 1845, 1838, 1790

Akutan Summit and Intra Caldera

July 2003. Jeff Wynn

CultureAkutan Peak

Akutan is a wonderful destination for ecotourism. Hiking on the island is diverse-wildflowers and berries abound on the hills and mountains. There is a thermal hot springs within hiking distance of the village. Hardy souls have climbed all the way to the crater of Akutan volcano, which is about seven miles west of the village. The volcano is active, with steady steam emissions and an occasional dusting of volcanic ash. There are no bears on the island, although you can see an occasional fox, and Aku-tan and the surrounding islands teem with birds and sea life. The whiskered auklet is found on the nearby Baby Islands, one of only two places it ex-ists in the world. Fishing is excellent in the waters around Akutan, and some of the largest halibut in the world have been caught in Akutan Pass at the west side of the Island.

Akutan is located on Akutan Island in the eastern Aleutians, one of the Krenitzin Islands of the Fox Island group. It is 35 miles east of Unalaska, and 766 air miles southwest of Anchorage. Akutan be-gan in 1878 as a fur storage and trading port for the Western Fur & Trading Company. The company’s agent established a commercial cod fishing and processing business that quickly attracted nearby Aleuts to the community. It was the only whaling station in the Aleutians from 1912 to 1942. The U.S. Government evacuated Akutan residents to the Ketchikan area in June 1942. The village was re-established after the war. Akutan is primarily a non-Native fishing community, although it is home to a traditional Aleut village.Commercial fishing and fish processing dominate Akutan’s cash-based economy. Trident Seafoods operates a major bottomfish plant west of the City. Deep Sea Fisheries also has a permanent process-

ing vessel in the bay. Nine residents hold commer-cial fishing permits. Subsistence hunting and fish-ing activities are minimal because the majority of residents are employed. The majority of the popula-tion lives in group quarters facilities.TransportationBoats and amphibious aircraft are the only means of transportation into Akutan. Cargo is delivered weekly by freighter from Seattle. Akutan has no air-strip, however, a seaplane base is available. Daily air service is available from nearby Unalaska.ClimateAkutan lies in the maritime climate zone. Tem-peratures range from 22 to 55. Precipitation averag-es 27.5 inches per year. Storms are frequent in the winter and fog is common in the summer.

Akutan has a deep and protective bay and is actu-ally 40 miles closer to the “crab fishing grounds” than Dutch Harbor. Although Akutan has no landing strip, has only 100 or so fulltime residents, and has no paved roads–only wooden boardwalks, is still one of the busiest fishing ports in the coun-try, and has one of the largest processors–Trident Seafoods–about 1/4 mile away from the village of Akutan. For this reason, and it’s remoteness,it was featured on Deadilest Catch.

First formed in 1878 as a fur trading post, Aku-tan village was also one of the first introduced to the crab fishing industries in the 1940′s and was home to several floating processors at that time. In 1942, when the Japanese attacked Unalaska, all residents were evacuated and thus had to re-es-tablish themselves as a village in 1944. Finally in 1979, it was incorporated as the “city” of Akutan.

Akutan is not only home to some of the busiest fishing ports, but also superstition. There is a tradition of throwing rocks onto a rock pile, if the rock stays on top, then you are fine and healthy. However; if the rock falls off, then you will die within the next year.

Kurt Schmidt participating in the rock toss.Wolfgang Brinck

Akutan Bay separtes the harbor from the Spring. While the volcano sits in the background.

Jeff WynnVolcanologist set up equiptment near Akutan’s hot springs.

Akutan Village

Jeff Wynn

Akutan Canary

Elevation: 8261 ft Latitude: 55.4173° NLongitude: 161.8937° W

Official Name:Pavlof VolcanoType:StratovolcanoLatest Activity: August 15, 2007Seismically Monitored: Yes

The most active volcano of the Aleutian arc

Pavlof Volcano

Type:

Pavlof is a composite cone

volcano located in the south-

western region of Alaska

about 600 kilometers south-

west of Anchorage. At its

summit Pavlof reaches an

elevation of 8,262 ft (2518).

The volcano consists of an-

destic magma, that contains

an intermediate content of

gases. Emission of lava and

ash has occurred during the

volcanoes eruptive stage.

Other geologic events are

also related to the volcanic

activity at Pavlof. Seismic ac-

tivity, mudflows, and flood-

ing have also occurred due

to Pavlof’s eruptive process.

Pavlof has been in a period

of eruptive pause during the

previous six weeks. Even

during these pauses the

threat of violent volcanic ac-

tivity is always present. For-

tunately the volcano is locat-

ed in a fairly remote region

and does not pose a great

threat to many people.

Form and structure

Mount Pavlof is a largely

snow-covered, cone-shaped

mountain with a high ridge

extending to the southwest

towards Little Pavlof. The

volcano is approximately

7 km in diameter and has

active vents on the north

and east sides close to the

summit (McNutt and oth-

ers, 1991). It is situated high

on the northeastern flank

of Emmons Lake caldera

along a northeast-trending

alignment of vents that in-

cludes Little Pavlof, Pavlof

Sister, and several intracal-

dera cones (Kennedy and

Waldron, 1955). The com-

posite volcano is relatively

undissected and is probably

Holocene in age. Pavlof lies

within the Shumagin seis-

mic gap (Davies and others,

1981).

Volcanic activity

Mount Pavlof is the most

active volcano in the Aleu-

tian volcanic arc with al-

most 40 relatively well-doc-

umented eruptions dating

back to 1790 (Newhall and

Dzurisin, 1988; Smithso-

nian Institution, 1976-1988;

McNutt, 1987; Coats, 1950;

Jaggar, 1932). It is so consis-

tently active that a question

sometimes arises as to what

constitutes a separate erup-

tion. Some Pavlof eruptions

have been short-lived (1-2

days duration) and similar

eruptions in the past may

have occurred unnoticed

in the sparsely populated

region. Pavlof eruptions

are typically strombolian to

vulcanian in character and

consist of rhythmic ejection

of incandescent bombs and

ash to heights of 200-300

meters above the summit

(McNutt and others, 1991);

spatter-fed lava flows ema-

nate from the summit vents

on occasion. Short-lived vol-

atile-rich vulcanian ash col-

umns reaching to heights of

10 kilometers or more have

been noted, usually at the

beginning of an eruption.

Eruptions tend to be either

magmatic or phreatomag-

matic and McNutt (1987)

found a correlation between

seismic activity and type of

eruption. Strong volcanic

tremor accompanied ma-

jor Strombolian magmatic

eruptions, whereas episodes

of explosion quakes, with

little to no volcanic tremor,

were diagnostic of minor

phreatomagmatic events.

The largest historical erup-

tion of Pavlof occurred on

December 6-7, 1911 at the

end of a five year period of ac-

tivity. A fissure vent opened

along the north flank, large

blocks were ejected, and

lava flows issued from the

fissure (McNutt, 1987). A

recent vigorous eruptive pe-

riod began mid-April, 1986

and continued through Au-

gust, 1988 (Smithsonian In-

stitution, 1986-88; McNutt

and others, 1991). Frequent

steam and ash emission, ex-

plosions, and strong tremors

accompanied summit lava

fountaining that fed sev-

eral agglutinate lava flows,

which in turn produced a

number of both hot

and cold, extensive mud-

flows.During the early course

of the eruption, the eruptive

vent shifted from the north

to the east side of the sum-

mit. The most recent erup-

tive episode at Mount Pavlof

began about September 11,

1996 and continued into

early 1997 (Neal and Mc-

Gimsey, 1997). The erup-

tive activity was strombolian

in character and similar to

most Pavlof eruptions. In-

termittent explosive activity

and lava fountaining were

recorded from two close-

ly-spaced vents high on the

northwest summit of the

volcano. Incandescent spat-

ter, spatter-fed flows, and

small lahars moved down

the northwest flank of the

volcano for the next four

months melting a narrow

channel through snow and

ice. Occasional elongate

plumes that rose to a max-

imum of 10 kilometers

above sea level (generally

less than 6 kilometers) and

extended up to several hun-

dred kilometers downwind

were detected on satellite

images and reported by pi-

lots. These clouds consist-

ed chiefly of vapor and gas

with minor amounts of ash.

Light ash fall was reported

on several occasions from

nearby communities.

Composition

Mount Pavlof is com-

posed of basaltic andesite

flows and pyroclastic rocks

that overlap similar rocks

from nearby Little Pavlof.

The flows are moderately

phyric with about 25% phe-

nocrysts, mostly plagioclase

with minor olivine and clin-

opyroxene. The agglutinate

flows of 1987 are of similar

andesitic composition.

Volcano Structure: The vol-

cano is 7km in diameter and

has two active vents, one lo-

cated on the northern side

and the other on the eastern

side (Miller et al, 1998) and

the overall outline of the vol-

cano appears cone shaped.

Historic Activity: Pavlof has

been erupting since 1790

and has experienced more

then forty periods of small

to moderate activity since

this time (Decker & Deck-

er, 1998) with the latest

eruption occurring from

September 1996 to January

1997 (Wallace et al, 2000).

The type of eruptions nor-

mally seen from Pavlof

consist of Strombolian and

Vulcanian eruptions where

the main components are

bombs and ash that normal-

ly reach heights of around

200 to 300m (Miller et al,

1998).

The largest eruption in Pav-

lof’s history occurred in

1911 when a fissure opened

expelling large lava flows,

together with these flows

large blocks were expelled

from the volcano. In more

recent times a period of

high activity was noted

from 1986 through to 1988

where large volumes of ash

and steam were expelled to-

gether with lava flows and

also lava fountains.

Eruptions and Activity

Start Date: 08.15.2007 Stop Date: 09.13.2007 Dating Technique: Historical RecordsVolcanic Explosivity Index (VEI): 2Eruptive Characteristics: Central vent eruption Explosive eruption Lava flow(s) Mudflow(s) (lahars)

“During the night, an intense thermal anomaly (TA) was visible in satellite images (Advanced Very High Resolution Radiometer-AVHRR), and seis-mic activity continued to increase in both number and duration of events per hour, clear signs that the unrest was escalating. On the morning of August 15, based on observations of the TA and increasing

seismicity, AVO elevated the Aviation Color Code/

Volcano Alert Level to ORANGE/WATCH and an-

nounced that an eruption was expected. With the

upgrade in color code, AVO began 24-hour surveil-

lance of the volcano. Later in the day, AVO received

eyewitness accounts from mariners of incandescent

blocks rolling down the eastern-southeastern flank

of the volcano during the previous night, beginning

around midnight. Pilots reported a thin, low-level

ash plume extending a few kilometers southwest

from the summit. After receiving these reports,

AVO established that the volcano was in eruption.

Aerial photographs taken on August 15 show lava

fountaining from a vent located about 200 m (650

ft) below the summit [see fig. 26 in original text].

“On August 16, strong seismic signals recorded

at a single station (PVV), located 8.5 km (5.3 mi)

southeast of the summit, heralded the passage of

lahars down the south flank; more than 41 lahar

events would be recorded by this station over the

next 29 days. Satellite observations of a strong ther-

mal anomaly (TA) [see fig. 27 in original text] and

nighttime incandescence at the summit reported

by local residents were indications of vigorous lava

eruption at the summit vent [see fig. 28 in original

text]. The seismic network recorded long periods of

volcanic tremor with repetitive explosions that in-

dicated nearly continuous Strombolian eruption.

In addition to the generation of lahars, this activity

produced low-level ash clouds (5-6 km ASL; 3.1-3.7

mi), and a spatter-fed lava flow that descended the

southeastern flank. By August 18, AVO personnel

in the field reported that vigorous eruption of lava

at the summit continued. Using a Forward Looking

Infrared (FLIR) camera, they determined that a 20-

to 50-m-wide, 65- to 165 ft-wide) 600 C (1,112 F) lava

flow extended 565 m (1,850 ft) from the vent down

the southeast flank [see figs. 29 and 30 in original

text]. Thermal data collected the next day indicated

that the outer part of this flow was about 140C (284

F) and had cooled considerably. The vent crater for

the last eruption of Pavlof, in 1996, was located on

the upper northwestern side of the summit. For

this eruption, the active vent migrated to the upper

southeastern side, about 200 m (650 ft) below the

summit [see figs. 31-33 in original text].

“Seismicity at Pavlof was elevated and steady

throughout the remainder of August and then be-

gan waxing and waning for the first week of Sep-

tember. A strong TA was present in satellite imag-

es, even through clouds, during this time. During

the second week of September, the seismicity began

showing signs of a steady decrease [see fig. 34 in

original text], and by September 13, seismicity de-

creased to low levels and only a minor steam plume

was visible above the volcano. A TA was last seen

on September 15, and AVO declared that the activity

had reached a lull by September 17. An AVO field

crew with clear views reported that all eruptive ac-

tivity had ceased during their visit on September 19,

and the Aviation Color Code /Volcano Alert Level

was downgraded to YELLOW/ADVISORY on Sep-

tember 20. The next 2 weeks of low seismicity and

no further signs of activity or unrest prompted AVO

to declare the eruption over (ending on September

13), and the Color Code/Volcano Alert Level was

downgraded to GREEN/NORMAL on October 5.

“Ash, a blocky lava flow, and multiple lahars were

generated by this eruption. Mixed ash and steam

clouds produced during the most energetic eruptive

period, mid-August to mid-September, reached alti-

tudes of 5-6 km (about 20,000 ft) ASL. The plumes

were diffuse, drifted primarily to the southeast over

the North Pacific Ocean, and many could not be de-

tected in satellite imagery. No ash reportedly fell on

nearby communities and there were no significant

impacts to aviation. AVO deployed a DRUM aerosol

impactor (particle collector) in Sand Point, 90 km

(56 mi) east of Pavlof, and collected fine ash (2.5-0.1

′m). Although no visible ash fallout was observed

during aerosol sampling, these results demonstrate

that volcanic ash was present in respirable size frac-

tions downwind of the volcano even during periods

of low ash emissions (Peter Rinkleff and Cathy Ca-

hill, AVO/UAFGI, written commun., 2010).

“Analyzed samples from the lava flow are basaltic

andesite in composition (53% SiO2), which is sim-

ilar to the products of previous Pavlof eruptions

(McNutt and others, 1991; Neal and McGimsey,

1997). Lahars were produced by interaction of hot

blocks and spatter from the lava flow with snow and

ice on the southeastern flank. The lahars inundated

an area over 2 km2 (0.78 mi2) and formed a debris

fan that extended 3.6 km (2.2 mi) from the base of

the volcano into Pavlof Bay [see fig. 35 in original

text].”

Start Date: 01.2001

Eruption is UNCERTAIN

Volcanic Explosivity Index (VEI): 1

Eruptive Characteristics:

Central vent eruption

Hydrothermal activity

Steam

McGimsey and others (2004) summarize 2001

steaming and other activity at Pavlof as follows:

“Principal/Teacher, John Concilius, has a good view

of Pavlof from his home in Nelson Lagoon. On

January 20, 2001 he observed through binoculars

steaming from multiple locations near the summit,

but none actually at the top of the volcano. He re-

ported that the steam was white and not discolored,

and, that the snow near the summit was clean with

no evidence of melting.

“He concluded by stating that this was the most

steaming he had seen at the volcano during the

past several years and that other villagers consid-

ered the steaming to be unusual.AVO remote sens-

ing specialist Dave Schneider analyzed Advanced

Very High Resolution Radiometer (AVHRR) satel-

lite images taken from January 18 to 22, 2001 and

found no evidence of increased thermal activity at

the volcano and no unusual seismicity was noted.

No further reports of steaming were forthcoming.

This may have been a meteorological phenomenon.

While working in Cold Bay in early June, Martin

LaFevers, Seismic Data Manager at UAFGI, ob-

served and photographed the summit of Pavlof

during a weather break; it appeared to be covered

with ash. A local pilot reported seeing ‘something

other than steam’ at the summit. Again, there was

no indication of anomalous seismicity.

Start Date: 09.11.1996Stop Date: 01.03.1997Dating Technique: Historical RecordsVolcanic Explosivity Index (VEI): 2Eruptive Characteristics: Central vent eruption Explosive eruption Lava flow(s) Mudflow(s) (lahars)

“Pavlof Volcano, historically the most active volca-

no in the Wrangell-Aleutian volcanic arc, began a

vigorous strombolian eruption in mid-September,

1996 (Neal, 1996). The eruption, which continued

into early 1997, occurred only two months after a

6-station seismic network was established near the

volcano.

“A NWS observer in Cold Bay noted steam and in-

candescent ejecta above the volcano at about 0830

ADT on September 16. Analysis of seismic data and

NOAA-12 and -14 AVHRR satellite images suggest

that the eruption likely began at a very low level by

September 11. Over the next few weeks, nearby res-

idents observed intermittent strombolian eruptions

from near the summit of the volcano. Pilots report-

ed incandescent bombs the size of pick up trucks

accompanied by minor ash clouds alternating with

steam plumes rising from a few hundred meters to

approximately 2 km above the volcano.

“Photographs from overflights on September 23

and AVO video from September 27-30 showed lava

fountains emanating from two vents (figs. 4A and

4B). One vent was located on the east edge of an

~150-m diameter crater that indented the northwest

summit of the volcano. A second, more active locus

of fountaining was perched on the west edge of this

crater 100-150 m below the summit. The two loci of

fountaining were about 100 m apart and were gen-

erally not synchronous in activity. The east vent was

less vigorous overall, producing intermittent puffs

of gray to dark gray ash and steam tens of meters

high. The west vent was the source of intermittent

bursts of incandescent spatter up to 300 m high.

“By September 23, a small spatter cone was form-

ing at the west vent and a collar of spatter, spat-

ter-fed flows, and small lahars extended about 500

meters down the ~30 degree northwest flank below

the summit crater. A lava flow formed by the coales-

cence and remobilization of heavy spatterfall and

direct spill over from the west vent plunged down

the steep flank, melting a narrow channel through

seasonal snow and glacial ice. By September 29, the

lava flow had reached the base of the cone, about

3.5 km from its source, and was beginning to wid-

en into a lobate fan. Dark lahar deposits extended

beyond the toe of this lava flow across the gently

sloping ground northwest of the volcano, coming

within about 40 m of AVO’s seismic station PV6.

By late October, a second lava flow issued from the

east vent and on December 2, when videotaped by

Alaska State Troopers, this flow was the more active

of the two and had nearly reached the base of the

cone in the saddle between Pavlof and Pavlof Sister.

“Eruptive activity became intermittent during the

month of December. Seismicity decreased abrupt-

ly early on December 4 and ash was not visible

above the regional cloud cover that obscured the

summit of Pavlof for several days. Brief episodes

of heightened seismicity occurred on December

10 (accompanied by at least one pilot report of ash)

and December 27. The last reliable observation of

ash emission occurred on January 3, although pilots

and observers in Cold Bay reported possible minor

ash in the steam plume over the volcano on a few

occasions through February 6. Collapse of unstable

agglutinate and hot fragmental debris on the steep

upper cone may well account for some of these

small ash plumes.

“During the first two weeks of the eruption, occa-

sional elongate clouds containing minor amounts

of ash were detected on NOAA AVHRR satellite im-

ages. During the third week, both pilot reports and

satellite image analysis documented larger but still

diffuse ash clouds trailing as far as 175 km down-

wind, but they rarely reached more than ~6 km

above the sea level. These clouds varied in length

from a few tens to several hundred km and were ob-

served intermittently, weather permitting, through

late December. On November 4, accompanying

some of the strongest seismicity of the eruption, a

plume was visible in Bands 4-5 extending 350 km

northeast of the volcano.

“In addition to elongate plumes, thermal anoma-

lies associated with high temperature material were

also recorded near the volcano’s active vents and

along the two main lava flow paths. The number of

saturated pixels on AVHRR images varied from 1 -

15 indicating areas of up to about 18 km2 above 37

degrees C (A.L. Roach, oral communication, 1997).

The last significant thermal anomaly was record-

ed in late December, however “warm” pixels were

noted during daily analysis of AVHRR data into

mid-February. Pilot reports and observations from

Cold Bay confirm continued warm ground around

the summit of the volcano as inferred from areas of

snow-melt.

“As in the 1986 eruption, the 1996 activity pro-

duced rubbly, fragmental lava flows that extend in

two main lobes down the northwest flank of the

volcano. Early in the eruption, these flows occu-

pied, at least in part, channels cut into the seasonal

snow and glacial ice on the volcano’s flank. Melting

of this snow and ice produced water and rock mix-

tures of unknown consistency that flowed out onto

the more gently sloping terrain northwest (and pos-

sibly northeast) of the volcano. As of this writing,

we do not know how far these lahars traveled or

what impact they had on the Cathedral River and

other drainages around Pavlof.

“Very light ashfall was reported in King Cove on the

night of October 5-6, Sand Point on October 19, and

Nelson Lagoon on October 28.”

More from Neal and McGimsey (1997): “On Octo-

ber 3, based on observed plume heights, the FAA is-

sued a Notice to Airmen (NOTAM) restricting flight

below ~7 km and within 10 nautical miles of Pavlof.

Higher levels of seismicity and more energetic ash

plumes began on October 15 and in response, the

FAA increased the altitude of restricted air space to

approximately 8 km and the size of the restricted

zone to a 25 mile radius around Pavlof. The FAA

continued to enforce this restriction until January

27, 1997. Although Pavlof ash plumes reached al-

titudes of 30,000 feet or more on a few occasions,

there were no serious disruptions in the North Pa-

cific airways.

“There were, however, impacts on local air traf-

fic. On November 4, a United States Coast Guard

(USCG) C-130 operating at low level over the Ber-

ing Sea was struck by lightning. The flight crew

also reported a “smoky” smell in the cockpit and a

fine dust throughout the plane. Subsequent discus-

sion with the USCG failed to positively identify the

source of this material. However, based on NWS

forecast winds during the time of this report, it ap-

pears unlikely that primary ejecta from Pavlof could

have been the culprit; rather, it is possible that low

level winds remobilized fine ash from the ground.

No sample of the material was recovered for analy-

sis.

“On November 27, 1996, a Reeve Aleutian Airways

flight aborted landing into Sand Point when the pi-

lot detected a brown haze that he interpreted to be

ash from Pavlof.”

Start Date: 01.05.1990 Stop Date: 03.05.1990Dating Technique: Historical RecordsVolcanic Explosivity Index (VEI): 2Eruptive Characteristics: Central vent eruption Explosive eruption

“Pavlof Volcano has been quiet since August 1988.

On January 5 and 6, 1990, Marsha Brown of the

FAA flight service at Cold Bay observed traces of

steam rising up to 100 m above the NE summit

vent that was trailing to the NE. The top of the vol-

cano was dark due to the melting of snow around

the summit vent. The volcano has been pure white

with snow for the winter up to this time. On March

5, several eruption plumes were observed.”

Start Date: 04.16.1986 Stop Date: 08.13.1988 Dating Technique: Historical RecordsVolcanic Explosivity Index (VEI): 3Lava Volume: 7.8 x 106 m3Area of Activity: NE & SE summit vents & flanksEruptive Characteristics: Central vent eruption Flank (excentric) vent Explosive eruption Pyroclastic flow(s) Lava flow(s) Mudflow(s) (lahars)

“The visual observations of the 1986 eruptions,

both aerial and on the ground, provide information

generally lacking from previous historic eruptions.

The physical characteristics of of the 1986 eruption

are probably similar to other historic summit erup-

tions, although the 1986 activity was more explo-

sive and of longer duration.

“The 1986 activity was chiefly Strombolian, charac-

terized by sporadic emissions of dark ash to heights

of up to 5 km; one exceptionally strong (probably

Vulcanian) eruptive event sent an ash column to

over 15 km on 18-19 April. The initial phase of the

eruption appears to have involved the summit vent

on the north side of the volcano which has been

the site of all Pavlof eruptions since the mid-1960s.

This eruptive phase lasted from 16 to 26 April and

included a hot rootless agglutinate flow that extend-

ed down the northwest flank of the volcano. The

deposit was actively degassing steam along its en-

tire length in late June. It had an estimated volume

of about 4x10^6 cubic meters and, at an elevation

of 760 meters, was 20-30 meters thick and 40-50

meters wide. The deposit was clast-supported and

fines-depleted, consisting entirely of glassy, slightly

vesicular andesitic basalt (SiO2 = 53.5%) bombs and

irregular masses of spatter with a maximum diam-

eter of about 1.2 meters. It was probably emplaced

during the initial and relatively violent vent-clear-

ing phases of the eruption on 16-28 April. Associ-

ated hot lahars caused melting of snow and ice and

extensive flooding in the Cathedral River drainage

north of the volcano. Heavy ash fall occurred north

and west of the volcano during the April activity; 2-3

mm of ash fell on the nearby communities of Cold

Bay, 35 km to the west, and King Cove, 48 km to the

southwest, but caused no damage.

“Eruptive activity began again in late May and was

highlighted by sporadic, but vigorous Strombolian

eruptive activity and by the formation of a new vent

high on the east flank of the volcano. Comparison

of aerial photography indicated that this is the first

major change in the vent geometry of Pavlof since

the early 1960s. The period of activity was charac-

terized by repeated small bursts of ash and cinder

to a few hundred meters above the vent and spatter

tossed a few tens of meters all accompanied by ex-

plosive, thunderlike reports. The explosions char-

acterizing the Strombolian eruption occurred at in-

tervals of 5-15 seconds during the half dozen times

the new vent was observed between 14 June and 30

June, suggesting a moderately rapid rate of magma

rise in the conduit. Only minor ash emission was

observed associated with the explosive ejection of

incandescent bombs from the new vent. Activity

from the old north vent during this time consisted

of steam emission with little or no ash.

“Close airborne examination of the new vent on 15

June revealed that a steep-sided, asymmetrical spat-

ter rampart, 50-75 m across, had been constructed

on the east, or downslope, side of the vent. A steep

chute, directly below the spatter rampart, contained

a steaming, rootless rubble flow. Further down the

volcano at an elevation of about 750 m, this flow

was about 100 m wide and consisted of bread-crust-

like bombs and irregular masses of lava and spatter,

up to 4 m in diameter, in an ash-rich, moderately

inflated matrix (in contrast to the flow on the north-

west flank). It was actively degassing, exhibiting

abundant steam fumaroles and occasional phreatic

eruptions. The flow, with an estimated volume of

3.8 x 10^6 cubic meters, also generated a number of

mudflows that continued downslope to about 600

m where the rubble flow-mudflow complex wid-

ened into three broad lobes. Below this elevation,

debris-laden water from the flows was contained in

a steep-sided small canyon.

“The nature of the material in the flow at this ele-

vation and the physical characteristics of the spat-

ter rampart at the vent strongly suggest that much

of the lower part of the flow may have resulted

from similar pyroclastic flow activity following par-

tial collapse of the oversteepened spatter rampart.

Throughout the course of the eruption, the steep

spatter rampart may have periodically become un-

stable and collapsed, either in whole or part, form-

ing hot, disaggregated pyroclastic flows cascading

down the chute. Where ice and snow were overrun

by the hot debris, mudflows were generated that

continued to travel down and fan out on the volca-

no’s lower slopes. In support of this hypothesis, a

pyroclastic flow was observed on 19 June moving

down the same chute from about 1400 m elevation

to about 900 m; the upper 1100 m of the volcano

was cloud-covered at this time.

An alternative scenario is that the pyroclastic flow

observed on 19 June resulted from a ‘boil-over’ of

the magma column at the vent following a larg-

er-than-usual explosion. Although no seismic evi-

dence for such an explosion was observed, the ob-

scuring cloud cover prevents an exact explanation

for the origin o fthe observed pyroclastic flow.

The April-August eruption is similar to, but some-

what stronger than most of the other Pavlof erup-

tions of this century (Simkin et al., 1981; McNutt

1987a) in terms of its Strombolian character. The

duration of the eruption, as indicated by lava foun-

tain activity and spatter ejection, however, appeared

to be much longer than for most modern eruptions.

This eruption also altered the physiography of the

summit area by forming a new vent. In contrast

to most recent eruptions (i.e., 1973-1983) that oc-

curred in the fall of the year, the 1986 eruption was

concentrated in the spring and summer.”

McNutt and others (1991) also give detailed in-

formation about the seismological data collected

during this eruption.

Information on the continuing volcanic activity in

1987 and 1988 is in other sources. From Reeder

(1990, pg. 53): “Numerous observations of tephra

and steam emissions were made during most of

1987 from NE and SE near summit vents and less

from a NE flank vent. Lava flows occurred on both

the NE flank and the SE flank of the volcano from

the summit vents down to at least a 1,000 m a.s.l.

elevation in January and February, form the NE

summit vent in May and June, and again from both

summit vents in August.” Please see the rest of

this text for detailed eruption observations in 1987.

From Reeder (1991): “Pavlof volcano has been fairly

active during 1986 and 1987 with tephra and lava

emissions occurring form several summit and flank

vents. During 1988, eruptive activity was restricted

to only small tephra and steam emissions from NE

near summit vent up through August 13, except for

one minor steam emission from a NE flank vent on

March 2. Since August 13, 1988, no eruptive activity

was observed for the rest of the year.”

Start Date: 11.11.1983 Stop Date: 12.181983 Dating Technique: Historical RecordsVolcanic Explosivity Index (VEI): 3Tephra Volume: > 1.3 ± 0.4 x 107 m3Area of Activity: Upper NE flankEruptive Characteristics:

“Eruptive activity was first observed from Sand Point (about 90 km E of the volcano) late on 14 November and pilots observed tephra columns the next afternoon. On 19 November a small vapor cloud rose approximately a hundred meters above the vent. Bad weather prevented observations until 26 November when Pavlof was visible until mid-afternoon from Cold Bay (about 60 km SW of the volcano). During the morning, a vapor plume containing a little ash rose to 4.5 km altitude. At intervals of approximately 30 minutes, puffs of dark ash were emitted. The intervals became short-

er, and by 1500 ash emission was nearly continu-ous.

“Through October and early November, a Lam-ont-Doherty seismic monitoring station near the volcano recorded background levels of 0-40 (usu-ally 0-30) small low-frequency events per day. A 30-minute burst of volcanic tremor began at 2000 on 4 November, and a 6-minute burst at 1757 on 9 November. Between 1430 on 11 November and 1100 on 13 November, 15 explosions were recorded. Several bursts of tremor of 1-2 minute duration oc-curred between 1700 and 1900, when continuous tremor started. Its amplitude gradually increased, and tremor began to saturate the seismograph at 1100 on 14 November. Tremor was strongest between midnight and 1200 on 15 November, and continued to saturate the seismograph until 2100 on 15 November when its amplitude began to decrease. Tremor remained continuous but at

low amplitude between 1300 on 16 November and 1200 on 18 November. Intermittent low-ampli-tude tremor and numerous low-frequency (B-type) events recorded after 1200 on 18 November were continuing on 21 November.

“Airline pilots last reported eruption clouds from Pavlof at 1400 on 15 December and there have been no eyewitness reports of eruptive activity since then. Six explosions were recorded be-tween 1600 and 2000 on 15 December by Lam-ont-Doherty’s 5-station seismic net 4.5 - 10 km from the volcano. One of these stations, about 7.5 km from Pavlof, detected bursts of harmonic tremor 17 December, 1100 - 18 December, 0330; 18 December, 0530 - 0615 and 1040-1110; 20 Decem-ber, 2200 - 2245; and 21 December, 2035 - 2048. Seismicity then decreased to the background level of several tens of events per day and remained at that level as of 26 January.

Eruption plumes were observed on 3 images returned 15-17 December from the NOAA 8 polar orbiting satellite. The images returned at 2101 on the 15th and 1031 on the 17th showed well-defined, relatively dense plumes extending 225 km E and 400 km NE from Pavlof above the weather cloud layer. A diffuse plume was observed on the image returned at 2108 on 18 December.

“No volcanic plumes were observed on other im-ages returned 15-21 December, but heavy weather clouds obscured the area.”

1982 Jul 15, 1981 Sep 25, 1980 Nov 8, 1980 Jul 6 ,1975 Sep 13, 1974 Sep 1, 1974 Mar 12, 1973 Nov 12, 1966 Mar 15 1958 May 17, 1953 Nov 25, 1951 Oct 3, 1950 Jul 31, 1936 - 1948, 1929 Mar 1, 1924 Jan 17, 1922 Dec 24, 1914 Jul 6, 1906 - 1911, 1901, 1894, 1892, 1880, 1866 Mar 14 ,1852, 1846 Aug 15

“The mountain burst with a loud ‘cannonade’ at this site [eastern slope of the mountain, where a pre-existing lava flow was] in August, 1846. Smoke poured out in clouds from a fissure, ash fell, and flames appeared. Flames also shot up from the summit. A northwest wind dispersed both the smoke and the ash that obscured from the in-habitants of Pavlof the islands at the mouth of the bay. The ash was carried to the village of Pavlof, where it was necessary to place a covering over the fish that were hung up. Smoke and ash were carried to Unga Island (about 85 kilometers to the east), where people also protected drying fish from ash by covering it with matting.”

Other Eruptions & Activity

CulturePavlof Volcano

The main challenge of climbing this peak is its re-moteness and the consequent difficulty of access. The peak is a 30 mi journey from the north side of Cold Bay. The climb itself is a straightforward snow climb, and the ski descent is recommended

The volcano is below the path of hundreds of daily international flight paths, and an explosive erup-tion could interrupt those operations, said Steve McNutt, a volcano seismologist with the observato-ry. Volcanic ash can enter an engine and make it seize up, he said.

Pavlof Bay is an inlet in Alaska located on the south-western edge of the Alaska Peninsula. It is on the peninsula’s south coast, is about 50 miles (80 kilo-meters) long, and lies directly north of the Pavlof Is-

lands. The 8,261-foot (2,518-meter) volcano Mount Pavlof is on its western shorePavlof is about nine miles from Pavlof Bay, a popular fish-ing ground. Pavlof Bay, on the southern side of the Alaska Peninsula, supported one of the world’slargest pandalid shrimp fisheries until 1979, and about 70% of the catches consisted of the northern shrimp

The English name for the island comes from Pitka Pavalof, a Creole of Russian-Native. In 1893, Pitka Pavalof and Ser-gei Gologoff Cherosky, Creoles of Russian-Native descent, found gold on Birch Creek in Interior Alaska. Learning of the discovery, prospectors jumped their claims and ar-gued that the claims were invalid because the men were Natives. The discovery attracted more non-Natives to the Yukon River and the town of Circle was founded are a group of culturally similar indigenous peoples inhabit-ing the Arctic regions of Greenland, Canada, the United States, and Russia. Inuit is a plural noun; the singular

is Inuk. The Inuit languages are classified in the Eski-mo-Aleut family.In the United States, the term Eskimo is commonly used in reference to these groups, because it includes both of Alaska’s Yupik and Inupiat peoples while “Inuit” is not proper or accepted as a term for the Inupiat. No collective term exists for both peoples other than “Eskimo”. How-ever, natives in Canada and Greenland view the name as pejorative and “Inuit” has become more common. In the United States, Inupiat live on the North Slope in Alaska and on Little Diomede Island. In Russia, they live on Big Diomede Island. The Greenlandic Inuit are the descen-dants of migrations from Canada and are citizens of Den-mark, although not of the European Union.