2011 Nabro eruption
Encyclopedia
The 2011 Nabro eruption was an eruption of the Nabro stratovolcano
in the Southern Red Sea Region of Eritrea
, which began on 12 June 2011 after a series of earthquakes. The eruption has killed seven and possibly a further 31 people and emitted the highest levels of sulfur dioxide
(SO2) ever observed from Earth's orbit. The ash cloud
from the eruption reached altitudes which disrupted airline traffic in the region. Until the eruption began, the volcano was thought to be extinct.
), in the Southern Red Sea Region. It was first thought to have originated at Dubbi Volcano
, but has been confirmed to be from the Nabro stratovolcano
in Eritrea, near the Ethiopia
n border.
On 17 June, the Volcanic Ash Advisory Center (VAAC) reported that the eruption had ceased, but NASA
's Aqua satellite
passed overhead providing MODIS
images on the 18th (at noon, local time) which showed an ash plume heading in west-north-westerly direction.
On 19 June, the volcano produced the highest level of sulfur dioxide
emissions in the earth's atmosphere ever detected from space. Satellite images showed a 15 km long lava flow. On 20 June, VAAC reported that the SO2 eruption was continuing.
From 22 June to 27 June, the eruption of sulfur dioxide, water vapour, and ash was confirmed to be still active by MODIS
pictures taken from the TERRA satellite.
24 June NASA Earth Observatory
provided this false-color
image (below) using the Advanced Land imager on the EO-1 satellite, showing that the lava flow from the 19th had not progressed significantly further, but that the eruption was ongoing.
30 June, at least some of the people who have been evacuated are reported to be in Hawra and Wadien.
On the 30 June eruption satellite images seem to show the volcano has stopped producing the ash cloud, but 1 July they show a fresh ash cloud eruption, diminishing until 4 July, when the ash eruption still appears to be ongoing , but by 6 July the ash cloud seems to have stopped being produced again.
12 July: The eruption was still ongoing though the SO2 emissions were much reduced after 7 July
and Sireru areas.
On 22 June, the Eritrean government reported a lava flow up to 1 kilometre (0.621372736649807 mi) wide and up to 15 metres (49.2 ft) high had surfaced in Seriru, southern Denkalia
, and destroyed vegetation for a distance of about 20 kilometres (12.4 mi).
On 30 June, the Eritrean government report suggested that the lava flow in Seriru had slowed to a speed of 20 metres (65.6 ft) per day. They also reported that in some places the flow was 4 kilometres (2.5 mi) wide and 20 metres (65.6 ft) high.
Note: It is still uncertain whether the information regarding the lava flow in "Seriru" refers to the main flow, as seen from the satellite images, though it seems likely.
A thick emission of smoke from new lava eruptions on 27 June were also reported in South Denkalia, Husele and Gagun.
.
The height of the ash cloud peaked at 14,000 m, implying a VEI
of 3 or 4.
Forecasters predicted correctly that the ash plume might reach Israel
, but no flights were cancelled at Ben-Gurion Airport on 14 June. Elsewhere, however, the ash cloud began disrupting air traffic on 14 June with UAE-based Emirates flights being cancelled; flights disruptions extended to other companies the following day. Hillary Clinton, Secretary of State for the United States, shortened her state visit to Ethiopia. Djibouti Airport was closed, and several airlines suspended flights to Ethiopia.
Mek'ele
and Asmara
were partially covered by volcanic ash.
By 19 June, ash had been deposited at least 60 km (37.3 mi) beyond the Ethiopian border in a WNW–to–SWS direction.
By 20 June, eight villages in the Biddu district
of Ethiopia
were covered by volcanic ash, affecting at least 5,000 people and polluting springs and streams. One entire community has not been heard from. Save the Children
reports many community members, especially children, are sick and in desperate need of medical attention. Vomiting and retching were reported as being common effects.
On 21 June, an Eritrean government statement reported seven people have been killed and three injured.
It was also reported that the Lake Afdera salt deposits now contain sulphuric acid, making the salt inedible.
On 6 July, reports suggest 48,000 people in the Bidu
, Afdera
, Erebti
, Elidar
, Teru
and Kori
woredas were in need of aid (with ash affecting food and water sources), and that the casualty total had reached 31 dead in the Bidu woreda.
Another 167,153 people, in the Elidar and Kori woreda
s, were reported as requiring monitoring according to the Afar regional
government. However a spokesman for the Ethiopean Government Agriculture Ministry
is reported to have said "We have looked at the document and I would like to make it clear that it is not a national document and that we have not endorsed it, the ministry has no record of casualties, it is still too early to say how many people had been affected and needed help."
, in the larger Danakil Depression
that holds many other active volcanoes. However, neither volcano thought potentially responsible for the eruption had been active in the past century, with Dubbi last erupting in 1861 and Nabro remaining quiet for thousands of years. No eruption of Nabro occurred before in recorded history. Basalt
, trachyte
and rhyolite
are among the rock types which Nabro has produced as lava
flows and pyroclastics.
Nabro Volcano
The Nabro Volcano is a stratovolcano located in the Southern Red Sea Region of Eritrea. It is located in the Danakil Depression. Prior to its 2011 eruption it was widely believed to be extinct.-Geology:...
in the Southern Red Sea Region of Eritrea
Eritrea
Eritrea , officially the State of Eritrea, is a country in the Horn of Africa. Eritrea derives it's name from the Greek word Erethria, meaning 'red land'. The capital is Asmara. It is bordered by Sudan in the west, Ethiopia in the south, and Djibouti in the southeast...
, which began on 12 June 2011 after a series of earthquakes. The eruption has killed seven and possibly a further 31 people and emitted the highest levels of sulfur dioxide
Sulfur dioxide
Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...
(SO2) ever observed from Earth's orbit. The ash cloud
Tephra
200px|thumb|right|Tephra horizons in south-central [[Iceland]]. The thick and light coloured layer at center of the photo is [[rhyolitic]] tephra from [[Hekla]]....
from the eruption reached altitudes which disrupted airline traffic in the region. Until the eruption began, the volcano was thought to be extinct.
Eruption
Satellite images showed a large volcanic eruption occurring shortly after 22.00 UTC 12 June (close to 01.00 June 13 local timeEast Africa Time
East Africa Time, or EAT, is a time zone used in eastern Africa. The zone is three hours ahead of UTC , which is the same as Arabia Standard Time, and also the same as Eastern European Summer Time....
), in the Southern Red Sea Region. It was first thought to have originated at Dubbi Volcano
Dubbi Volcano
The Dubbi Volcano is a stratovolcano located in the Southern Red Sea Region of Eritrea. Its peak elevation is 1625 m. There have been four known eruptions. In 1400 lava was determined to have reached the Red Sea while in 1861 ash was thrown over 250 km from the volcano...
, but has been confirmed to be from the Nabro stratovolcano
Stratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...
in Eritrea, near the Ethiopia
Ethiopia
Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...
n border.
On 17 June, the Volcanic Ash Advisory Center (VAAC) reported that the eruption had ceased, but NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
's Aqua satellite
Aqua (satellite)
Aqua is a multi-national NASA scientific research satellite in orbit around the Earth, studying the precipitation, evaporation, and cycling of water. It is the second major component of the Earth Observing System preceded by Terra and followed by Aura .The name "Aqua" comes from the Latin word...
passed overhead providing MODIS
MODIS
The Moderate-resolution Imaging Spectroradiometer is a payload scientific instrument launched into Earth orbit by NASA in 1999 on board the Terra Satellite, and in 2002 on board the Aqua satellite...
images on the 18th (at noon, local time) which showed an ash plume heading in west-north-westerly direction.
On 19 June, the volcano produced the highest level of sulfur dioxide
Sulfur dioxide
Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...
emissions in the earth's atmosphere ever detected from space. Satellite images showed a 15 km long lava flow. On 20 June, VAAC reported that the SO2 eruption was continuing.
From 22 June to 27 June, the eruption of sulfur dioxide, water vapour, and ash was confirmed to be still active by MODIS
MODIS
The Moderate-resolution Imaging Spectroradiometer is a payload scientific instrument launched into Earth orbit by NASA in 1999 on board the Terra Satellite, and in 2002 on board the Aqua satellite...
pictures taken from the TERRA satellite.
24 June NASA Earth Observatory
NASA Earth Observatory
NASA Earth Observatory is an online publishing outlet for NASA which was created in 1999. It is the principal source of satellite imagery and other scientific information pertaining to the climate and the environment which are being provided by NASA for consumption by the general public...
provided this false-color
False-color
A false-color image is an image that depicts a subject in colors that differ from those a full-color photograph would show.-True- and false-color:...
image (below) using the Advanced Land imager on the EO-1 satellite, showing that the lava flow from the 19th had not progressed significantly further, but that the eruption was ongoing.
30 June, at least some of the people who have been evacuated are reported to be in Hawra and Wadien.
On the 30 June eruption satellite images seem to show the volcano has stopped producing the ash cloud, but 1 July they show a fresh ash cloud eruption, diminishing until 4 July, when the ash eruption still appears to be ongoing , but by 6 July the ash cloud seems to have stopped being produced again.
12 July: The eruption was still ongoing though the SO2 emissions were much reduced after 7 July
Other eruptions
Small eruptions were also reported in the AfamboAfambo
Afambo is one of the 29 woredas in the Afar Region of Ethiopia. It is named after Lake Afambo, located at the border of this woreda with Asayita, near the international border with Djibouti. Part of the Administrative Zone 1, Afambo is bordered on the south by the Somali Region, on the west by...
and Sireru areas.
On 22 June, the Eritrean government reported a lava flow up to 1 kilometre (0.621372736649807 mi) wide and up to 15 metres (49.2 ft) high had surfaced in Seriru, southern Denkalia
Denkalia
Denkalia was a province of Eritrea until 1996, when it was divided between present day Northern Red Sea and Southern Red Sea regions. Its capital was Assab....
, and destroyed vegetation for a distance of about 20 kilometres (12.4 mi).
On 30 June, the Eritrean government report suggested that the lava flow in Seriru had slowed to a speed of 20 metres (65.6 ft) per day. They also reported that in some places the flow was 4 kilometres (2.5 mi) wide and 20 metres (65.6 ft) high.
Note: It is still uncertain whether the information regarding the lava flow in "Seriru" refers to the main flow, as seen from the satellite images, though it seems likely.
A thick emission of smoke from new lava eruptions on 27 June were also reported in South Denkalia, Husele and Gagun.
Ash cloud
The eruption has ejected a large ash cloud near the Eritrea–Ethiopia border region, extending over 1000 km (621.4 mi) into neighboring SudanSudan
Sudan , officially the Republic of the Sudan , is a country in North Africa, sometimes considered part of the Middle East politically. It is bordered by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the...
.
The height of the ash cloud peaked at 14,000 m, implying a VEI
Volcanic Explosivity Index
The Volcanic Explosivity Index was devised by Chris Newhall of the U.S. Geological Survey and Stephen Self at the University of Hawaii in 1982 to provide a relative measure of the explosiveness of volcanic eruptions....
of 3 or 4.
Forecasters predicted correctly that the ash plume might reach Israel
Israel
The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...
, but no flights were cancelled at Ben-Gurion Airport on 14 June. Elsewhere, however, the ash cloud began disrupting air traffic on 14 June with UAE-based Emirates flights being cancelled; flights disruptions extended to other companies the following day. Hillary Clinton, Secretary of State for the United States, shortened her state visit to Ethiopia. Djibouti Airport was closed, and several airlines suspended flights to Ethiopia.
Mek'ele
Mek'ele
Mek'ele , also transliterated as Makale, is a city in northern Ethiopia and the capital of the Tigray Region. It is located some 650 kilometers north of the capital, Addis Ababa, at latitude and longitude with an elevation of 2084 meters above sea level...
and Asmara
Asmara
Asmara is the capital city and largest settlement in Eritrea, home to a population of around 579,000 people...
were partially covered by volcanic ash.
Effects
On 16 June, the inhabitants of Afambo, Nebro and Sireru were evacuated.By 19 June, ash had been deposited at least 60 km (37.3 mi) beyond the Ethiopian border in a WNW–to–SWS direction.
By 20 June, eight villages in the Biddu district
Bidu (woreda)
The Bidu woreda is one of the woredas in the Afar Region of Ethiopia, it forms part of the Administrative Zone 2....
of Ethiopia
Ethiopia
Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...
were covered by volcanic ash, affecting at least 5,000 people and polluting springs and streams. One entire community has not been heard from. Save the Children
Save the Children
Save the Children is an internationally active non-governmental organization that enforces children's rights, provides relief and helps support children in developing countries...
reports many community members, especially children, are sick and in desperate need of medical attention. Vomiting and retching were reported as being common effects.
On 21 June, an Eritrean government statement reported seven people have been killed and three injured.
It was also reported that the Lake Afdera salt deposits now contain sulphuric acid, making the salt inedible.
On 6 July, reports suggest 48,000 people in the Bidu
Bidu (woreda)
The Bidu woreda is one of the woredas in the Afar Region of Ethiopia, it forms part of the Administrative Zone 2....
, Afdera
Afdera
Afdera is one of the 29 woredas in the Afar Region of Ethiopia. It is named after the saline Lake Afdera, located in the southern part of the Afar Depression...
, Erebti
Erebti
Erebti is one of the 29 woredas in the Afar Region of Ethiopia. It is named after the Erebti River, a stream that flows east from the Ethiopian highlands into the Afar Depression, part of which lies in the eastern part of this woreda...
, Elidar
Elidar (woreda)
Elidar is one of the 29 woredas in the Afar Region of Ethiopia. Part of the Administrative Zone 1, Elidar is bordered on the south by the Awash River which separates it from Asayita, on the west by Dubti, on the northwest by the Administrative Zone 2, on the northeast by Eritrea, and on the east...
, Teru
Teru
Teru is one of the 29 woredas in the Afar Region of Ethiopia. Part of the Administrative Zone 4, Teru is bordered on the south by Aura, on the southwest by Gulina, on the west by Yalo, and on the north and east by the Administrative Zone 2...
and Kori
Kori (woreda)
Kori is one of the 32 woredas in the Afar Region of Ethiopia. It is part of the Administrative Zone 1. The administrative center is Guluble Af.Kori was created by a decision of the Afar Regional Cabinet on 4 February 2007, from the northern part of Dubti....
woredas were in need of aid (with ash affecting food and water sources), and that the casualty total had reached 31 dead in the Bidu woreda.
Another 167,153 people, in the Elidar and Kori woreda
Woreda
Woreda is an administrative division of Ethiopia , equivalent to a district . Woredas are composed of a number of Kebele, or neighborhood associations, which are the smallest unit of local government in Ethiopia...
s, were reported as requiring monitoring according to the Afar regional
Afar Region
Afar is one of the nine ethnic divisions of Ethiopia, and is the homeland of the Afar people. Formerly known as Region 2, its current capital is Asayita; a new capital named Semera on the paved Awash - Asseb highway is under construction....
government. However a spokesman for the Ethiopean Government Agriculture Ministry
Ministry of Agriculture and Rural Development (Ethiopia)
The Ministry of Agriculture and Rural Development is the Ethiopian government ministry which oversees the agricultural and rural development policies of Ethiopia on a Federal level...
is reported to have said "We have looked at the document and I would like to make it clear that it is not a national document and that we have not endorsed it, the ministry has no record of casualties, it is still too early to say how many people had been affected and needed help."
Geology
The erupting volcano is located within the Afar TriangleAfar Depression
The Afar Triangle is a geological depression that is caused by the Afar Triple Junction which is part of the Great Rift Valley. It overlaps Eritrea, Djibouti and the entire Afar Region of Ethiopia. The Afar Triangle includes the Danakil Depression and the lowest point in Africa, Lake Asal...
, in the larger Danakil Depression
Danakil Depression
The Danakil Depression is a desert basin which lies in the Danakil Desert in north-eastern Ethiopia and southern Eritrea. It belongs to the homeland of the Afar people. It lies up to 100 m below sea level as a result of tectonic activity caused by plate movements...
that holds many other active volcanoes. However, neither volcano thought potentially responsible for the eruption had been active in the past century, with Dubbi last erupting in 1861 and Nabro remaining quiet for thousands of years. No eruption of Nabro occurred before in recorded history. Basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
, trachyte
Trachyte
Trachyte is an igneous volcanic rock with an aphanitic to porphyritic texture. The mineral assemblage consists of essential alkali feldspar; relatively minor plagioclase and quartz or a feldspathoid such as nepheline may also be present....
and rhyolite
Rhyolite
This page is about a volcanic rock. For the ghost town see Rhyolite, Nevada, and for the satellite system, see Rhyolite/Aquacade.Rhyolite is an igneous, volcanic rock, of felsic composition . It may have any texture from glassy to aphanitic to porphyritic...
are among the rock types which Nabro has produced as lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...
flows and pyroclastics.