Active volcanoes / Aktive vulkaner:
Anatahan, Marianas, Pacific Ocean  

The elongated, 9-km-long island of Anatahan consists of two coalescing volcanoes with a
2.5 x 5 km, E-W-trending summit depression formed by overlapping summit craters.
The floor of the steep-walled crater of the younger eastern cone is only 68 m above sea level.
The spareness of vegetation on the most recent lava flows on Anatahan indicate that they
are of Holocene age (Meijer and Reagan 1981).

Once, 266 people lived on three now-uninhabited Northern Mariana Islands -- Anatahan,
Alamagan and Agrihan. Each island is marked by the crater of a volcano. People from those
northern islands were evacuated to Saipan in April 1990 because of earthquake activity on Anatahan.

February 5th, 2008
Report prepared by the U.S. Geological Survey. Satellite images from February 3, 2008 show a diffuse ash plume extending west from the volcano for approximately 60 miles (100 km). It is not possible to precisely determine the
height of this ash plume from the currently available data but is likely less than 5,000 feet (1500 m) above sea level.
Elevated seismic tremor levels persist and sulfur dioxide emissions continue to be detected in satellite data.
The USGS is changing the Aviation Color Code to Orange and the Alert Level to watch as a result of the observed
ash emissions. There is no indication that Anatahan is building to a more energetic eruption.
Emissions of volcanic ash, gas, and steam will likely continue and could pose a hazard to low-flying aircraft in the
vicinity of the volcano and for tens of miles downwind. The USGS continues to monitor the situation closely.

Tuesday, May 31st, 2005

Ash plume is seen rising from Anatahan volcano in this photo taken from an aircraft at about
2:30pm Sunday. Anatahan Island could be discerned beneath the ash cloud.
Photo: © Agnes E. Donato

Ash plumes from Anatahan's erupting volcano continue to affect navigational visibility, with ash
emissions still going on despite fluctuating seismicity on the island. In a joint report, the U.S.G.S.
and the Emergency Management Office said yesterday that visibilities of less than 3 nautical miles
below the plume have been reported. On Sunday, they said at least two ships beneath the plume
in the Philippine Sea reported visibilities of just 1.2 and 2.5 nautical miles.

Citing satellite images taken by the Air Force Weather Agency, the USGS and the EMO said
yesterday that a plume of ash and steam was rising to an altitude of 14,000 feet from the volcano.
The agencies said the plume, although less denser than Sunday's, extended about 450 nautical
miles northwest of Anatahan.

The agencies also said that a thin plume of ash and volcanic smog extended about 1,300 nautical
miles from west-southwest to northwest of the volcano's summit, affecting visibility. But they said
that seismicity on Anatahan has been declining since yesterday morning after escalating in the
past days.

Friday, April 8th, 2005

Plume from the Anatahan volcano images on April 5 from a satellite.
Credit: NASA GSFC, MODIS Rapid Response Team

At 10.00 local Anatahan time on April 8: Since the explosive eruption of Anatahan on April 6,
seismicity has been very low, within several percent of the background level.
The current ash plume extends at least 115 nautical miles west of the island.

Thursday, April 7th, 2005
Volcanic ash blanketed the skies above the Northern Mariana Islands yesterday, forcing
motorists to drive with their headlights on in the middle of the day and bombarding the
Emergency Management Office with phone calls from panic-stricken residents.
Strong sulfur odor permeated the air and the morning sky was as dark as night.
It was like nighttime at nine in the morning. It was so dark that streetlights, which operate
with automatic sensors, turned themselves back on.

Wednesday, April 6th, 2005
Anatahan Volcano has erupted, shooting a thick plume of ash 50,000 feet (15,000 meters)
into the air and darkening the skies. Officials in the U.S. commonwealth Wednesday placed
Anatahan Island off limits until further notice, advising aircraft to exercise caution and avoid
coming within 10 nautical miles (18.4 kilometers) of the area.

Children were sent home early from school as ash fell on Saipan and Tinian, but there were no
injuries or major disruptions reported. Seismic signals began to climb slowly on Tuesday at
about 10 p.m. local time. The seismicity peaked about five hours later.
Anatahan volcano has been belching ash and gas for some time, but today's early morning
eruption was bigger than usual. "It was a pretty major eruption," according to NWS.
"Probably the biggest since the initial eruption a few years ago and by looking at our radar data,
we saw that the cloud probably went up to at least 50,000 feet".

Along with those suffering from respiratory problems, babies, children, and the elderly should
not stay outside for prolonged periods of time. Civil defense is keeping an eye on the situation,
So far no flights at the Guam International Airport have been affected by the ash.

Friday, March 25th, 2005
As of the 24th of March, the Washington Volcano Ash Advisory Center (WVAAC) has
reported that volcanic and seismic activity increased at Anatahan during 14-21 March in
comparison to previous weeks. During 14-17 March, seismicity increased and steam rose
a few hundred meters above the volcano. The inner East crater had been nearly filled with
lava flows and lapilli since early January. According to seismic data, a small eruption began
on 18 March at 1544. On 19 March the Washington VAAC issued an advisory that an
ash plume was visible on satellite imagery below 4 km (13,100 ft) a.s.l. Small explosions that
began late on 20 March lasted for 14 hours. No emissions were visible on satellite imagery.

Monday, January 17th, 2005
The eruptions have increased in intensity but have become less frequent. Late on January 15,
the seismicity level dropped to near zero for a couple of hours before surging to a new high for
the year, 50 percent above the previous high.Ashfall has reached Saipan, located about 120
kilometers south of Anatahan. Tropical storm Kulap changed the wind direction sending ash
and volcanic emissions to inhabited islands of Commonwealth of the Northern Mariana islands.

Some residents have mistaken the ashfall for normal dust and have not taken precautionary
measures to avoid contact. Residents have continued with outdoor activities over the weekend,
like swimming and having picnics, despite the change in the air quality. The Department of Public
Health issued a volcanic ash health advisory for the whole CNMI as early as Saturday.
The advisory urges residents, especially infants, elderly people and those with lung problems like
asthma, to stay indoors. Between 9 a.m. and 10 a.m. yesterday, a strong smell of sulphur
reached Saipan. The health secretary advised residents to protect their water sources from
falling volcanic ash. Water cisterns should be closed and covered and roof-collection systems
should be turned off. Residents are encouraged to consume only bottled water until their
alternate source of drinking water has been flushed and cleared of all volcanic debris.

Tuesday, January 11th, 2005
Since January 6, the amplitude of the explosion signals increased slowly to about double the
values by midnight January 9-10 UT, with explosions occurring every 3-10 seconds. On January
10, the amplitude of the explosion signals plunged suddenly to half the values at the start of the
day. The amplitudes then surged again, nearly doubling by 1800 UT. Then, by midnight UT ,
the amplitudes again dropped to half the values at the start of the day.

The ash plume likely extends 100 km or more downwind at this time. This ongoing strombolian
eruption is very similar in nature and size to the previous eruption of April-July 2004.

Monday, January 10th, 2005
The explosions have slowly increased in size by about 40 percent since they began, and they
are now occurring about once every 10 seconds. This ongoing strombolian eruption is very
similar to the previous eruption, in April-July 2004.
Every time there are explosions, there were black rocks -- sometimes red -- being thrown
several hundred feet into the air," said EMO's Juan Takai Camacho, who was part of a team
aboard a fixed-wing aircraft that flew over the island Friday.

During the 45-minute overflight, Camacho said he observed no lava flowing from the volcano's
crater. With the new batch of eruptions, ash may again bury Anatahan, which Camacho stated
appeared to have been regaining its greenery after more than a million cubic yards of ash were
deposited on land and sea following the big eruption in 2003. Thick ash billowing from the crater
made the overflight difficult, Camacho stated.
Pacific Daily News

Saturday, January 8th, 2005
The VAAC reported the plume at 0225 UT on January 6 as 60 km long, blowing westward,
by 20 km wide. During the last 48 hours, the seismic signals have changed from harmonic tremor
to a somewhat broader band tremor with frequent explosion signals recorded by the microphones
several times per minute. A relatively full scale strombolian eruption is now underway and has
been for the last 2 days. The eruption type and activity level are both very similar to the peak
level of eruptive activity that was reached during the previous eruption, during April-June 2004.

An overflight was accomplished yesterday by EMO personnel. They report ash rising apparently
well above 5000 feet. A dome is visible in the crater, and bombs were observed rising to less than
2000 ft. We believe that an ash plume likely extends to 100 km or more downwind at this time.

Friday, January 7th, 2005
The volcano became active again on Tuesday. Although the volcano is not currently dangerous
to most aircraft , conditions may change rapidly, and aircraft should pass upwind of Anatahan
or farther than 30 kilometres downwind.
It is the fourth eruption of Anatahan since it suddenly burst into life in May 2003, sending smoke
and ash 9,000 metres into the air. Three airlines - Continental Micronesia, Air New Zealand
and Japan Airlines - had confirmed the latest eruption was reaching 4,500 metres.
Under an emergency declaration, Anatahan has been declared off limits to all but scientific expeditions until the end of January.

Thursday, January 6th, 2005
The third historical eruption began at Anatahan on January 4, 2005. After two days of occasional
small long-period events, the so far very small eruption began at or soon after 0540 UTC
accompanied by a slow ramp-up of harmonic tremor. No large event or explosion signal initiated
the eruption, nor are any significant signals observable on the two microphones. Guam tower
confirmed that a low plume of ash up to about 500 ft was visible this morning January 5 (MI).
The seismic signals seem to indicate a low viscosity magma effectively at the surface with little
buildup of magmatic pressure.

Thursday, July 29th, 2004
Seismicity at Anatahan approached the highest levels of the year on 23 July.
That day, Strombolian explosions frequently threw mostly coarse material up to hundreds
of meters at intervals of tens of seconds to minutes. On 26 July, there were nearly continuous
ash-and-gas emissions. By 27 July, seismicity had decreased to very low levels in comparison
to the previous 2 months, and seismic signals indicated that the frequent individual explosions
that occurred during the previous week decreased greatly in size and number.

Thursday, May 20th, 2004
During 13-17 May, volcanic activity continued at Anatahan. Explosions occasionally threw
volcanic material hundreds of meters out of the crater, and steam-and-ash emissions
probably rose several hundred meters above the volcano.
On 17 May the seismic energy release nearly doubled in comparison to the previous
several days, but remained well below the peak level reached on 24 April.

The view is looking north-northwest toward the island's southern flank. Anatahan is ~9 kilometers
in length. The SB2000 data were collected by R. Dziak. The digital elevation model of Anatahan
Island was created by Steve Schilling (U.S. Geological Survey) and geo-referenced with control
points provided by Frank Trusdell (U.S. Geological Survey).

Tuesday, April 27th, 2004
An ash warning for airlines flying in the vicinity of the plume from the volcano on Anatahan
island was lifted yesterday. However, as of 4 p.m. yesterday, seismic activity on the island
continued to increase steadily

The ash plume was yesterday blowing west-northwest and away from inhabited islands
in the Commonwealth of the Northern Mariana Islands.
After the eruption on saturday,
a group of scientists from the National Science Foundation who happened to be on Saipan
for an unrelated project flew to Anatahan in a helicopter and determined the eruption
had sent the ashes about 1.200 m into the air.

(From Pacific Daily News)

Monday, April 26th, 2004
Anatahan's volcano continues to vent out its fury, with eruptions comparable to those of
last year's and ash emissions below an altitude of 4,000 feet. Seismic activity on Anatahan
increased even more abruptly since Saturday, even as the agencies reported sustained high
seismicity for over a week. There was no reported ashfall on Saipan so far.

The magnitude of the eruptions reached "a high level unseen since summer 2003,"
the EMO and the USGS said. The agencies noted the abrupt development from mere quiet
effusion of lava to energetic eruptions. "The eruptive activity now appears to be as energetic
as some of the eruptions of mid-June 2003," the agencies said.

The eruption in 2003.

Sunday, April 25th, 2004
Almost a year since it's last eruption, Anatahan erupts again, and has been spewing ashes
up to an altitude of 10,000 ft. that is drifting northwest in the direction of the Philippines..
So far, Saipan, Tinian, and Rota remain free from any ash fall, but as the eruption was
just yesterday morning, it is still too early to say how the eruption developes.

The government in Saipan, received reports of massive ash spewing on Anatahan around
1pm yesterday. It was not immediately clear though, if this latest episode is as powerful as
the first time when the volcano erupted on May 10, 2003. (See below)

CNMI Emergency Management Office, reports that the ash emission from the volcano
reached up to about 3,000 ft but the winds are pushing it to higher altitude,
reaching up to 9,000 to 10,000 ft.

USGS had reportedly issued a warning that ash emissions from the volcano could be
hazardous to aircraft. Volcanic ash emissions less than two weeks after the May 10 eruption
last year, had prompted air carriers plying Saipan and Guam to cancel flights due to hazy conditions during that time.

The center had reported that last year's eruption resulted in volcanic ash spreading to over one million square kilometers above the Pacific Ocean, reaching the skies of Palanan City in the Philippine's Isabela province.

The government has placed Anatahan under an emergency declaration, directing the public, in
cluding sea vessels and airplanes, to stay away from within 30 nautical miles around Anatahan.
(Based on an article from

Friday, June 13th, 2003

Satellite image from June 12th.

As of the 12th of June, the U.S. Geological Survey office in Guam has reported that emissions
of ash and gas at Anatahan, which began on 10 May, continued during 4-10 June.
The highest reported ash plume rose to ~7.6 km a.s.l. on 3 June at 2013 according to
observations from an aircraft. USGS and Commonwealth of the Northern Mariana Islands
Emergency Management Office (EMO) personnel visited Anatahan on 6 June and repaired the
seismic station in the east crater. EMO recommended that the state of emergency for Anatahan
be extended due to continued volcanism, and that Anatahan residents be permanently relocated.

Tuesday, May 27th, 2003
Strong winds have carried ash from the Anatahan to Saipan. A public health advisory for
volcanic ash and sulphur gas remains in effect. Scientists say the volcanic plume largely is
moving eastwards, but any change in wind direction could pose health risks to residents
on Tinian, Rota and Guam as well as Saipan.

The Department of Public Health says residents with respiratory problems such as asthma or bronchitis should limit their time outdoors if they experience symptoms such as coughing or shortness of breath.
ABC Radio Australia News

Monday, May 26th, 2003

Eruption cloud, from the east crater of Anatahan Volcano,
rising to a height of about 15,000 feet, on May 10, 2003.
View from the NE side of the island, looking in a southwesterly direction
(Photo USGS/HVO)
The Anatahan volcano is still active. However, as the typhoon Chan moves away to the NE,
the ash plume of the volcano is at present not visible on satellite pictures. The plume is
embedded in the typhoon circulation and should have been oriented towards the E or SE.
Typhoon Chan, Marianas, is a large storm which has been tracking NNE at 7 kts.
Maximum sustained winds were estimated at 85 kts, gusting to 105 kts.

Friday, May 23rd, 2003

from NASA's Space Station Science, Picture of the Day, May 23rd, 2003
with links to, for which we are thankful.
Photo credit: ISS Expedition 7 science officer Ed Lu

Last day the cloud has turned South-
South-Westward, and is still very
easy to identify, as shown on this
satellite photo from yesterday.


For the past week, a column of dark volcanic ash has been erupting from Anatahan Volcano
in the Northern Mariana Islands, burying parts of the volcano with more than half a meter
of ash and sending an eruption cloud more than 1,000 kilometers to the west.

Commercial flights between Hawai`i and the Philippines and Hong Kong, and between Japan,
Saipan, Guam, Australia, and New Zealand, pass over volcanoes of the Northern Mariana
Islands. When an explosive eruption from these islands sends volcanic ash and gas high
enough to affect aircraft, it is extremely important for pilots already in the air, and airline
dispatchers on the ground, to receive immediate notification of the activity and location
of the resulting eruption cloud.

Thursday, May 15th, 2003
The Mayor’s Office believes the eruption may have killed many of the 5,000 feral goats and
more than 2,000 wild pigs on the island which had been subject of an eradication program.
A team of volcano experts and scientists from the US Geological Survey are on standby
and set to fly to Anatahan to study the volcano.

Wednesday, May 14th, 2003

©Marianas Variety
The Washington Volcanic Ash Advisory Center estimated the plume at an altitude of
16,000 feet, spreading to approximately 1 million square kilometers above the Pacific Ocean.
The plume was just about 175 kilometers from Palanan City in the Philippines' Isabela province, and ashfall could be felt on the area soon.
(Pacific Islands Development Program)

Ash (indicated by the greyish color) is visible drifting westward over the Philippines.

As of the 14th of May, the U.S. Geological Survey office in Guam has reported that a state
of emergency has been declared in the Northern Mariana Islands as the eruption of Anatahan
volcano appeared to be gaining strength and sending high-level ash over a wide area.
Due to the volcanic activity on Anatahan, volcanic ash and a high level plume is ongoing in the
area, presenting a continuing threat of adverse impact in the waters and air space around
Anatahan. The islands of Saipan, Tinian and Aguigan may also experience effects from
the ash and plume.

The Commonwealth of the Northern Mariana Islands says it may extend a 30 day
state-of-disaster emergency, after the eruption of a volcano on Anatahan island.
Anatahan is now unsafe for human habitation and private citizens can no longer travel there.
(ABC Radio Australia News)

May 13th, 2003
U.S. Geological Survey office in Guam has reported that Anatahan volcano on the uninhabited
island of Anatahan, 80 miles north of Saipan, erupted 9 pm Saturday night (May 10th), but so
far poses no danger to populated areas. A group returning to Saipan saw a red, flashing glow
coming from Anatahan that looked like blazing military fire.

A National Weather Service statement issued yesterday said only ash at high altitude is moving
over Guam, Saipan, Tinian and Rota. The ash emission will not have any significant effect for
people, but is producing a brownish haze up in the air.


 USGS Currewnt update on Anatahan Volcano
 The Marianas Islands

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