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From: Biniam Tekle (biniamt@dehai.org)
Date: Tue Jun 28 2011 - 09:02:32 EDT
Satellite Images Show Ongoing Activity At Nabro Volcano
By Mark Dunphy - Tue Jun 28, 12:12 am
*A volcano that erupted for the first time in recorded history more than two
weeks ago is continuing to emit large volumes of ash and sulphur dioxide
(SO2) into the skies over Eritrea and northern Ethiopia.*
The Nabro stratovolcano, which is located close to Eritrea’s border with
Ethiopia in northeast Africa, temporarily affected air traffic two weeks ago
when the ash plume drifted as far away as Israel, Jordan, Turmenistan and
the Central African Republic (CAR).
Images from the *MODIS*
<http://lance.nasa.gov/imagery/modis-browse/>satellite showed a thick
ash plume drifting over Eritrea’s border into
Ethiopia Monday afternoon. The volcanic ash was drifting SSW. Winds in the
region were light NNE when the below images were captured at midday Monday.
<http://www.irishweatheronline.com/wp-content/uploads/2011/06/Nabro-pictured-from-space-at-midday-on-27-June-2011.-Image-MODIS.jpg>
Nabro pictured from space at midday on 27 June 2011. Image MODIS
<http://www.irishweatheronline.com/wp-content/uploads/2011/06/Close-up-view-of-Nabro-at-midday-on-27-June-2011.-Image-MODIS.jpg>
Close up view of Nabro at midday on 27 June 2011. Image MODIS
Meanwhile,the below pair of satellite images are among the first detailed
pictures of the erupting vent and lava flows. They were acquired by
the Advanced
Land Imager <http://eo1.gsfc.nasa.gov/technology/alihome1.htm> (ALI) aboard
the Earth Observing-1 <http://eo1.gsfc.nasa.gov/> (EO-1) satellite on June
24, 2011.
The bright red portions of the false-color image (top) indicate hot
surfaces. Hot volcanic ash glows above the vent, located in the center of
Nabro’s caldera. <http://volcanoes.usgs.gov/images/pglossary/caldera.php> To
the west of the vent, portions of an active lava flow (particularly the
front of the flow) are also hot. The speckled pattern on upstream portions
of the flow are likely due to the cool, hardened crust splitting and
exposing fluid lava as the flow advances. The bulbous blue-white cloud near
the vent is likely composed largely of escaping water vapor that condensed
as the plume rose and cooled. The whispy, cyan clouds above the lava flow
are evidence of degassing from the lava.
The natural-color image (lower) shows a close-up view of the volcanic plume
and eruption site. A dark ash plume rises directly above the vent, and a
short, inactive (cool) lava flow partially fills the crater to the north. A
gas plume, rich in water and sulfur
dioxide<http://so2.gsfc.nasa.gov/pix/daily/0611/afar_0611z.html>(which
contributes a blue tint to the edges of the plume) obscures the upper
reaches of the active lava flow. Black ash covers the landscape south and
west of Nabro.
[image: NASA Earth Observatory image by Robert Simmon, using EO-1 ALI data.
Caption by Robert
Simmon.]<http://www.irishweatheronline.com/wp-content/uploads/2011/06/a2.jpg>
NASA Earth Observatory image by Robert Simmon, using EO-1 ALI data. Caption
by Robert Simmon.
[image: NASA Earth Observatory image by Robert Simmon, using EO-1 ALI data.
Caption by Robert Simmon. Instrument: EO-1 -
ALI]<http://www.irishweatheronline.com/wp-content/uploads/2011/06/b2.jpg>
NASA Earth Observatory image by Robert Simmon, using EO-1 ALI data. Caption
by Robert Simmon. Instrument: EO-1 - ALI
Meanwhile, the eruption of the stratovolcano has created a new landmass,
according to the director general of Mines at the Ministry of Energy and
Mines, Mr. Alem Kibreab. Mr. Alem said that the ash and lava emitted from
the Southern Red Sea region volcano has created a new land mass measuring
hundreds of square metres. The director general also disclosed that a team
composed of geological and volcanic experts is conducting studies in the
area.
According to reports, 7 people have died while 3 people have sustained
injuries due to the eruption. The Ministry confirmed that inhabitants of the
area have been moved to safer locations while at the same time they are
being given basic provisions.
Nabro began erupting on Sunday 12 June, 2011, the first ever recorded
eruption of the stratovolcano. The resultant ash plume, extending up to 15km
into the air, led to some flight cancellations in neighbouring Sudan,
Djibouti and Ethiopia. The ash cloud was carried as far away as Saudi
Arabia, Israel, Turkmenistan, Somalia, the Central African Republic (CAR)
and Egypt. A second eruption on Thursday 16th June sent a massive ash plume
westnorthwest over Sudan threatening to bring further disruption to air
traffic in the east Africa region. The volcano has continued to emit
varying amounts of ash, SO2 and water vapour since..
Part of the Afar Triangle, Nabro is one of many volcanic caldera complexes
in the north easternmost part of the East African Rift valley region. The
stratovolcano is located in the Danakil Depression, close to Eritrea’s
border with Ethiopia and north of Djibouti, and has not erupted in at least
150 years. According to data, a similar volcanic eruption in Eritrea
occurred in 1861, in Dubbi, Southern Denkel.
Nabro is the most prominent of 3 large volcanoes (Nabro, Dubbi, Mallahle) in
the region, each containing a large summit caldera. Nabro comprises lava
domes, lava flows, and two calderas, 8 and 5 km in diameter.
The volcano is located along the Great Rift Valley, also known as the East
African Rift. the divergent plate boundary extends from the Afar Triple
Junction southward across eastern Africa, and is in the process of splitting
the African Plate into two new separate plates, the Nubian Plate and the
Somali Plate. Seismic activity is frequent in Ethiopia In 1961 alone three
thousand tremors were recorded from the centre of the Wollo province
resulting in a 20km fissure being opened on the slopes of the Borkena
graben.
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