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Nabro

Photo of this volcano
  • Country
  • Volcanic Region
  • Landform | Volc Type
  • Last Known Eruption
  • 13.37°N
  • 41.7°E

  • 2,218 m
    7,277 ft

  • 221101
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

Most Recent Weekly Report: 28 September-4 October 2011 Citation IconCite this Report

According to NASA's Earth Observatory, satellite images of Nabro acquired on 28 September showed heat from the vent in the central crater, and from an area 1.3 km S of the vent that indicated an active lava flow. A small and diffuse plume rose from the vent. A region of seemingly thicker black ash (that completely covered the sparse vegetation) was noted S of the crater and thinner layers of ash (with some areas of visible vegetation) flanked either side of the region.

Source: NASA Earth Observatory


Most Recent Bulletin Report: May 2014 (BGVN 39:05) Citation IconCite this Report

Thermal alerts ended mid-2012; revised 2011 plume heights; uplift mechanisms debated

This report shows satellite thermal alerts from the MODVOLC system showing that they continued for 7 months after the end of coverage in our one report on Nabro's June 2011 eruption (BGVN 36:09), with the last alert occurring on 3 June 2012.

What has emerged regarding the 2011 Nabro eruption since our one previous report is a much more detailed eruptive timeline and some substantially taller plume-height estimates. These new and more carefully assessed details came out in at least eight papers and three technical comments (see References below).

The initial Toulouse Volcanic Ash Advisory Center estimates cited in BGVN 36:09 were made in the time-limited operational setting that identifies volcanic ash for aviation safety. Those altitude estimates, which included maximum plume heights on 13 June 2011 in the range of 9.1-13.7 km altitude, have since been reassessed using an array of satellite and ground-based instruments and processing strategies. The revised heights in the subsequent papers often determined plume altitudes above the 16-18 km tropopause and into the stratosphere. Absent in our earlier report but well documented in the papers was evidence of a 16 June 2011 eruptive pulse.

Overall, Nabro erupted a total SO2 mass of at ~1.5 Tg (Clarisse and others, 2012), making the eruption the largest SO2 emitter of the 2002-2012 interval (Bourassa and others, 2013). The various papers and the technical comments have also framed debate on how and when Nabro's plume entered stratosphere.

Thermal alerts. This report does not contain any new in situ observations at Nabro. Table 1 shows MODVOLC thermal alerts during November 2011 and into 2012 on the basis of the number of days with alerts in these months. Those alerts stem from observations made with the MODIS instrument that flies on the Terra and Aqua satellites. Our previous report discussed alerts as late as 5 November 2011, but additional alerts were issued later in the month. For this table, January 2012 was the month with the largest number of days with alerts, 15 days. As of late 2014, the last posted alert was issued on 3 June 2012.

Table 1. MODVOLC thermal alerts recorded for Nabro from November 2012 through September 2014. Courtesy of MODVOLC.

Month Number of days with alerts
November 2011 11
December 2011 08
January 2012 15
February 2012 12
March 2012 07
April 2012 11
May 2012 11
June 2012 01

Although the earlier alerts may signify ongoing eruption, some of the later alerts could stem from ongoing post-eruptive thermal radiance from potentially thick lava flows. Absence of alerts could be the result of clouds masking the volcano, although that is unlikely significant in the terminal alert registered in June 2012. It also bears noting that the alerts are at a fairly high threshold.

References. Bourassa, AE, Robock, A, Randel, WJ, Deshler, T, Rieger, LA, Lloyd, ND, Llewellyn, EJ, and Degenstein, DA, 2012, Large Volcanic Aerosol Load in the Stratosphere Linked to Asian Monsoon Transport. Science 337 (6090):78-81. DOI: 10.1126/science.1219371.

Bourassa, AE, Robock, A, Randel, WJ, Deshler, T, Rieger, LA, Lloyd, ND, Llewellyn, EJ, and Degenstein, DA, 2013, Response to Comments on "Large volcanic aerosol load in the stratosphere linked to Asian Monsoon transport. Science, 339 (6120), 647, DOI: 10.1126/science.1227961.

Clarisse, L., P.-F. Coheur, N. Theys, D. Hurtmans, and C. Clerbaux, 2014, The 2011 Nabro eruption, a SO2 plume height analysis using IASI measurements, Atmos. Chem. Phys., 14, 3095-3111,DOI:10.5194/acp-14-3095-2014.

Clarisse, L., Hurtmans, D., Clerbaux, C., Hadji-Lazaro, J., Ngadi, Y., & Coheur, P. F., 2012, Retrieval of sulphur dioxide from the infrared atmospheric sounding interferometer (IASI). Atmospheric Measurement Techniques Discussions, 4, 7241-7275 [13 March 2012; revised from 2011 version] www.atmos-meas-tech.net/5/581/2012/; DOI:10.5194/amt-5-581-2012.

Fairlie, T. D., Vernier, J.-P., Natarajan, M., and Bedka, K. M., 2014, Dispersion of the Nabro volcanic plume and its relation to the Asian summer monsoon, Atmos. Chem. Phys., 14, 7045-7057, DOI:10.5194/acp-14-7045-2014, 2014.

Fromm, M, Nedoluha, G, and Charvat, Z, 2013, Comment on "Large Volcanic Aerosol Load in the Stratosphere Linked to Asian Monsoon Transport." Science 339 (6120). DOI: 10.1126/science.1228605.

Fromm, M, Kablick, G (III), Nedoluha1, G., Carboni, E., Grainger, R., Campbell, J, and Lewis, J., 2014, Correcting the record of volcanic stratospheric aerosol impact: Nabro and Sarychev Peak, Journal of Geophysical Research. Atmospheres. [Early, online version, accessed August 2014] DOI: 10.1002/2014JD021507

Pan, LL, and Munchak, LA, 2011, Relationship of cloud top to the tropopause and jet structure from CALIPSO data. Journal of Geophysical Research: Atmospheres (1984-2012) 116.D12 (2011).

Penning de Vries, M. J. M., Dörner, S., Pukite, J., Hörmann, C., Fromm, M. D., & Wagner, T. (2014). Characterisation of a stratospheric sulfate plume from the Nabro volcano using a combination of passive satellite measurements in nadir and limb geometry. Atmospheric Chemistry and Physics, 14(15), 8149-8163.

Theys, N., Campion, R., Clarisse, L., Brenot, H., van Gent, J., Dils, B., Corradini, S., Merucci, L., Coheur, P.-F., Van Roozendael, M., Hurtmans, D., Clerbaux, C., Tait, S., and Ferrucci, F.: Volcanic SO2 fluxes derived from satellite data: a survey using OMI, GOME-2, IASI and MODIS, Atmos. Chem. Phys., 13, 5945-5968, doi:10.5194/acp-13-5945-2013, 2013.

Vernier, JP, Thomason, LW, Fairlie, TD, Minnis, P., Palikonda, R, and Bedka, K M, 2013. Comment on "Large Volcanic Aerosol Load in the Stratosphere Linked to Asian Monsoon Transport." Science 339 (6120). DOI: 10.1126/science.1227817.

Information Contacts: Hawai'i Institute of Geophysics and Planetology (HIGP) MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI (URL: http://modis.higp.hawaii.edu/); and Toulouse Volcanic Ash Advisory Centre (VAAC) (URL: http://www.meteo.fr/vaac/).

Weekly Reports - Index


2011: June | July | September


28 September-4 October 2011 Citation IconCite this Report

According to NASA's Earth Observatory, satellite images of Nabro acquired on 28 September showed heat from the vent in the central crater, and from an area 1.3 km S of the vent that indicated an active lava flow. A small and diffuse plume rose from the vent. A region of seemingly thicker black ash (that completely covered the sparse vegetation) was noted S of the crater and thinner layers of ash (with some areas of visible vegetation) flanked either side of the region.

Source: NASA Earth Observatory


13 July-19 July 2011 Citation IconCite this Report

Based on analyses of satellite imagery, the Toulouse VAAC reported that on 16 July an ash plume from Nabro rose to altitudes below 5.5 km (18,000 ft) a.s.l. A weak eruption detected on 17 July decreased through the day then appeared to have stopped.

Source: Toulouse Volcanic Ash Advisory Centre (VAAC)


29 June-5 July 2011 Citation IconCite this Report

A satellite image of Nabro acquired on 29 June showed a clear view of the caldera and the vent within the active crater near the middle of the caldera. Lava flows to the W, and within the crater (E and S of the vent), continued to be hot. A brown ash plume rose from the vent and drifted S.

Source: NASA Earth Observatory


22 June-28 June 2011 Citation IconCite this Report

A satellite image of Nabro acquired on 22 June showed a gas-and-ash plume rising from the caldera and drifting W. According to a news article, the eruption resulted in at least seven deaths, injured many, and displaced thousands in Eritrea, and affected about 5,000 Ethiopians living near the border. Two satellite images acquired on 24 June show the erupting vent, plumes and emissions, and lava flows in detail. One false-color image highlighted hot areas throughout the lava flow and flow front, as well as hot material above the vent. Gas emissions rising from the lava flow were also detected. A natural-color image showed fresh but cooled lava flows in the N part of the caldera. A dark ash plume rose from the vent, and at higher altitudes a plume composed of water vapor and sulfur dioxide drifted W and obscured the active lava flow. Black ash deposits covered the landscape to the S and W. During 22-26 June large amounts of sulfur dioxide in the region continued to be detected by satellite images. Based on analyses of satellite imagery, the Toulouse VAAC reported that during 26-27 June plumes rose to altitudes up to 6.1 km (20,000 ft) a.s.l.

Sources: Sudan Tribune; Toulouse Volcanic Ash Advisory Centre (VAAC); NASA Earth Observatory; NASA Global Sulfur Dioxide Monitoring


15 June-21 June 2011 Citation IconCite this Report

An eruption from Nabro that started on 12 June continued to produce a plume. Based on analyses of satellite imagery, the Toulouse VAAC reported that during 15-20 June plumes comprised mostly of water and sulfur dioxide rose to altitudes of 6.1-7.9 km (20,000-26,000 ft) a.s.l. Ash was occasionally detected near the volcano. Satellite imagery posted on MODIS Web showed a dark brown ash plume fanning out to the SW on 19 June. A thermal satellite image acquired at night on 19 June revealed a 15-km-long lava flow that had traveled NW. A high-altitude plume, likely rich in water vapor, rose from the erupting vents and a diffuse ash-rich plume drifted SW.

News articles stated that ash had covered a well-known mine that produces edible salt, and had contaminated food and water sources. During 15-16 June several airlines cancelled some domestic and international flights, including in and out of Addis Abeba (Ethiopia), neighboring Djibouti, and Khartoum (Sudan).

Sources: Bloomberg; NASA MODIS Rapid Response System; Toulouse Volcanic Ash Advisory Centre (VAAC); NASA Earth Observatory; Addis Fortune


8 June-14 June 2011 Citation IconCite this Report

According to the USGS Earthquake Hazards Program, an earthquake swarm was detected during the evening of 12 June on the border of Ethiopia and Eritrea, in the vicinity of Nabro, the most prominent of three volcanoes with large summit calderas aligned in a NE-SW direction SW of Dubbi volcano. The swarm began at 1837 with an M 5.1 earthquake. Several more were detected between M 4.3 and 5.1 over the next few hours. Two M 5.7 earthquakes at depths of 10.1 km and 9.9 km were detected at 2332 on 12 June and 0003 on 13 June, respectively.

The Toulouse VAAC reported that an eruption from Nabro (originally attributed to Dubbi) started between 0000 and 0200 on 13 June. An eruption plume initially rose to altitudes of 9.1-13.7 km (30,000-45,000 ft) a.s.l. then was later detected at altitudes of 6.1-10.7 km (20,000-35,000 ft) a.s.l. during 13-14 June. According to the Eritrean Ministry of Information, ashfall covered hundreds of kilometers and the government evacuated area residents. Witnesses noted that the eruption had started at about 2100 on 13 June. Satellite images that same day showed the plume drifting more than 1,000 km NW, over parts of Sudan. On 14 June a detached ash cloud was detected over southern Israel according to news articles. A plume from Nabro was not obvious on satellite imagery.

Sources: Eritrean Ministry of Information; US Geological Survey Earthquake Hazards Program; The Jerusalem Post; Toulouse Volcanic Ash Advisory Centre (VAAC); NASA MODIS Rapid Response System


Bulletin Reports - Index

Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

09/2011 (BGVN 36:09) First historically observed eruption began 13 June 2011

05/2014 (BGVN 39:05) Thermal alerts ended mid-2012; revised 2011 plume heights; uplift mechanisms debated




Information is preliminary and subject to change. All times are local (unless otherwise noted)


September 2011 (BGVN 36:09) Citation IconCite this Report

First historically observed eruption began 13 June 2011

The first documented historical eruption at Nabro began on 13 June 2011. Nabro lies in a belt of active volcanoes that follows the Red Sea and lies in the Afar Triangle in Southern Eritrea near the border with Ethiopia (figure 1). An earthquake swarm began on 12 June 2011. The swarm included an M 5.1 earthquake in the vicinity of Nabro and early the next day, satellite remote sensing revealed a large ash plume. Tensions remain in the war-ravaged border region of Eritrea and Ethopia; despite an official cease fire, access to the region remains limited. Nabro's eruption delivered large and concentrated SO2 plumes, dropped ash over extensive areas, forced thousands of evacuations, and, according to the Eritrean government, led to fatalities.

Figure (see Caption) Figure 1. Nabro's location in Eritrea and with respect to neighboring countries in East Africa. (Inset) The location of Eritrea in Northeastern Africa along the Red Sea.

Nabro lies in the midst of a chain of volcanoes (figure 2; dashed lines indicate trends of volcanic ranges). Each of the three main volcanoes on figure 2 contains a prominent summit crater or caldera (figures 3 and 4).

Figure (see Caption) Figure 2. A regional map showing Nabro in the volcanic range of the same name (Nabro Volcanic Range, NVR). According to the map's authors (Wiart and Oppenheimer, 2005), the NVR trends with a bearing of N26°E and extends 110 km from the SE margin of the Afar depression at Bara' Ale to islands in the Red Sea. Nabro marks the highest point in the NVR (which the map authors state as 2,248 m, some 30 m higher than the value given in our header, above). Taken from Wiart and Oppenheimer (2005).
Figure (see Caption) Figure 3. Satellite image of the Nabro region taken in February 2000 processed to form a shaded-relief map. When viewed in color, the lower elevations are in green, grading through yellow to red to blue at the highest elevations on the rims of the various nested calderas. Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the NASA Space Shuttle Endeavour. The scale is inexact, and the Eritrean-Ethiopian border is approximate. Courtesy of NASA Jet Propulsion Laboratory.
Figure (see Caption) Figure 4. Astronauts on the NASA International Space Station took this photograph of Nabro on 30 January 2011, showing the pre-eruption morphology of Nabro and some smaller volcanic centers to the S. Nabro's outer crater is ~8 km across and opens to the SSW. Centered within that larger caldera lie two much smaller craters, one inside the other. The inner wall of the caldera has steep sides, some as high as 400 m. Courtesy of NASA Earth Observatory.

Seismic precursors. According to an article in the Ethiopian Journal issued on 13 June 2011, a series of moderate earthquakes struck the Eritrea-Ethiopia border region on the evening of 12 June 2011. The U.S. Geological Survey (USGS) reported a total of 14 light-to-moderate earthquakes in the border area, the two strongest being M 5.7, both centered in Eritrea. The series began at 1837 hours when an M 5.1 earthquake struck ~128 km WNW of Assab, a port city in the southern Red Sea region of Eritrea. It occurred at ~10 km depth and was followed by seven smaller ones, between M 4.5 and M 4.8, during the next 2.5 hours. Those were then followed by earthquakes of M 4.7, 4.8, and 5.0. Soon after, at 2332 hours, the first M 5.7 earthquake struck about 123 km WNW of Assab at a depth of 10 km. It was quickly followed by the second M 5.7 earthquake and other smaller earthquakes.

Eruption. The Toulouse Volcanic Ash Advisory Center (VAAC) reported that an eruption from Nabro (originally attributed to Dubbi, ~25 km NNE of Nabro) started between 0300 and 0500 on 13 June 2011. The eruption plume initially rose to altitudes of 9.1-13.7 km; it was detected at altitudes of 6.1-10.7 km during 13-14 June.

According to the Eritrean Ministry of Information, ashfall covered hundreds of square kilometers, and the government evacuated area residents. Eye witnesses first observed the eruption at about 2100 on 13 June. Satellite images that same day showed the plume drifting more than 1,000 km NW, over parts of Sudan. On 14 June 2011 news articles reported that a detached ash cloud was detected over southern Israel. Throughout the eruption, satellite images were nearly the only source of new information about activity.

The Addis Fortune website reported that, although the major eruption took place in Nabro, large quantities of dust from the earthquake occurred in the town of Afambo (~26.5 km N of Nabro). It also reported that the Eritrean government announced that inhabitants had moved to safe areas. The well-known Afdera salt accumulation site in the depression was covered in volcanic ash. The salt, extracted for human and other consumption, had thus become inedible. The ash clouds also caused the cancellation of some domestic and international flights in Eritrea and Ethiopia.

During the week of 15-21 June 2011, Nabro continued to produce plumes. Based on analyses of satellite imagery during that period, the Toulouse VAAC reported that plumes comprised mostly of water and SO2 rose to altitudes of 6.1-7.9 km (figure 5). Ash was occasionally detected near the volcano. Satellite imagery posted on the MODIS/MODVOLC website showed a dark brown ash plume fanning out to the SW on 19 June. By 19 June, the altitude of Nabro's ash plume dropped from a maximum of 14 km to 7.6 km. The ash halted flights in eastern Africa for a time. The eruption killed seven people, according to the Eritrean government, although later reports appeared to discount that. Other reports indicated that thousands were affected in both Eritrea and Ethiopia, though news was sparse.

Figure (see Caption) Figure 5. This large and intense SO2 gas cloud emitted from Nabro was captured by the OMI satellite's spectrometer during the time interval between 1017 and 1159 UTC on 19 June 2011. The SO2 traveled to the S and the W during the period, and some portions of intense gas clearly extended off this image in those directions. The scale at right is in Dobson Units (DU, a unit common in atmospheric research and widely described in text books). The mass of SO2 depicted on this image was ~103 kilotons (kt); the area of cloud was ~591,000 km2; the maximum SO2 values on the image occurred at the location 40.87°N and 13.14°E and reached 68 DU. Courtesy of Simon Carn, and NASA Global Sulfur Dioxide Monitoring Aura/OMI website.

A thermal satellite image acquired at night on 19 June revealed a 15-km-long lava flow that had traveled NW (figure 6). A high-altitude plume, likely rich in water vapor, rose from erupting vents; a diffuse ash-rich plume drifted SW. The more restricted plume on 19 June enabled images to reveal a NW-trending lava flow that extended ~15 km from the summit area, although the area of venting remained obscured by a water-rich plume.

Figure (see Caption) Figure 6. A thermal infrared, false-color image of Nabro on 19 June 2011 taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). Hot areas are bright with new lava flows shown in white, and cold areas are dark. Thermal infrared data were combined with a shaded relief image to show the terrain. Courtesy of NASA Earth Observatory.

On 22 June a report from the Eritrea Ministry of Energy and Mines stated that the ash and lava covered hundreds of square meters. A satellite image acquired that day showed a gas-and-ash plume rising from the caldera and drifting W. An image from 24 June showed the erupting vent, plumes and emissions, and lava flows (figure 7).

Figure (see Caption) Figure 7. A false-color image of Nabro, acquired by the Advanced Land Imager (ALI) aboard the Earth Observing-1 (EO-1) satellite on 24 June 2011, highlighted hot areas throughout the lava flow and flow front, as well as above the vent in the center of the caldera. The bright red portions indicate hot surfaces. To the W, portions of an active lava flow (particularly the flow-front) are also hot. The speckled pattern on upstream portions of the flow is likely due to hardened crust splitting and exposing fluid lava. An ash plume rose from the vent, and at higher altitudes a plume composed of water vapor and SO2 drifted W and obscured the active lava flow. Black ash deposits covered the landscape to the S and W. Courtesy of NASA Earth Observatory.

During 22-26 June large amounts of SO2 in the region continued to be detected by satellite images. Based on analyses of satellite imagery, the Toulouse VAAC reported that during 26-27 June plumes reached altitudes of up to 6.1 km.

An annotated satellite image acquired on 29 June (figure 8) showed a clear view of the eruption. NASA Earth Observatory analysts labeled what they inferred to be the vent, an area in the main caldera's center and likely engulfing both the two inner craters with either very hot lava or with fresh tephra that probably formed cones or other features whose surface cooled quickly. An ash plume rose from the vent and drifted S. Based on analyses of satellite imagery, the Toulouse VAAC reported that on 16 July an ash plume from Nabro rose to altitudes below 5.5 km. A weak eruption detected on 17 July decreased through the day then appeared to stop.

Figure (see Caption) Figure 8. A visible and infrared image of Nabro from the Advanced Land Imager (ALI) on the Earth Observing-1 (EO-1) satellite, taken 29 June 2011. The image shows the still-hot lava flow, fresh ash over the lower half of the photo (dark landscape, accentuated by slanting lines or dashes in the lower portion of the image). A diffuse ash plume rose from the vent. The hottest lava is indicated by orange-red, with cooler zones fading to black. The ~15 km long flow on the W side of the volcano is mottled with black, indicating areas with cooler surfaces. The lava to the E and S of the vent appears to be newer, since little of it has cooled. Image and interpretation of NASA Earth Observatory (with lines and additional labels added).

According to an article by the South Africa Weather and Disaster Information Service (SAWDIS) dated 30 June 2011, a press release from the Eritrean Government disclosed that, though the advancing lava in the nearby village of Sireru had slowed down, a large area of land covered by vegetation was destroyed and river beds were covered within 24 hours.

NASA's Earth Observatory noted that images from 28 September showed heat from the vent in the central crater and from an area 1.3 km S of the vent that indicated an active lava flow. A small and diffuse plume rose from the vent. A region of seemingly thicker black ash (that completely covered the sparse vegetation) was noted S of the crater and thinner layers of ash (with some areas of visible vegetation) flanked either side of the region.

MODVOLC Thermal Alerts. Prior to 12 June 2011 the MODVOLC website indicated that no thermal alerts were measured over at least the past 5 years. The onset of thermal alerts was a 3-pixel area detected at 0115 on 13 June 2011 (2215 on 12 June UTC), followed by nearly daily measurements through 1 September 2011. Since that date, several alerts per week have been measured for Nabro up to 5 November 2011.

Some individual satellite passes measured high numbers of alerts. A 9-pixel alert occurred on 8 September, and as many as 95 pixels were measured for a single satellite pass at 2245 on 17 June. Other single orbital passes during June-August measured alerts of 50 to more than 70 pixels.

Reference. Wiart, P., and Oppenheimer, C., 2005, Large magnitude silicic volcanism in north Afar: the Nabro Volcanic Range and Ma'alalta volcano, Bulletin of Volcanology, v. 67, no. 2, pp. 99-115.

Information Contacts: NASA Earth Observatory (URL: http://earthobservatory.nasa.gov); MODIS/MODVOLC, Hawai'i Institute of Geophysics and Planetology (HIGP) MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI (URL: http://modis.higp.hawaii.edu/); Toulouse Volcanic Ash Advisory Centre (VAAC) (URL: http://www.meteo.fr/vaac/); NASA Global Sulfur Dioxide Monitoring (URL: http://so2.gsfc.nasa.gov/index.php); Jet Propulsion Laboratory (URL: http://photojournal.jpl.nasa.gov); S.A. Weather and Disaster Information Service. (SAWDIS) (URL: http://saweatherobserver.blogspot.com); Ethiopian Journal (URL: http://www.ethjournal.com); Addis Fortune (URL: http://www.addisfortune.com); Simon Carn, Dept of Geological and Mining Engineering and Sciences, Michigan Technological University, 1400 Townsend Dr., Houghton, MI 49931, USA (URL: https://so2.gsfc.nasa.gov/).


May 2014 (BGVN 39:05) Citation IconCite this Report

Thermal alerts ended mid-2012; revised 2011 plume heights; uplift mechanisms debated

This report shows satellite thermal alerts from the MODVOLC system showing that they continued for 7 months after the end of coverage in our one report on Nabro's June 2011 eruption (BGVN 36:09), with the last alert occurring on 3 June 2012.

What has emerged regarding the 2011 Nabro eruption since our one previous report is a much more detailed eruptive timeline and some substantially taller plume-height estimates. These new and more carefully assessed details came out in at least eight papers and three technical comments (see References below).

The initial Toulouse Volcanic Ash Advisory Center estimates cited in BGVN 36:09 were made in the time-limited operational setting that identifies volcanic ash for aviation safety. Those altitude estimates, which included maximum plume heights on 13 June 2011 in the range of 9.1-13.7 km altitude, have since been reassessed using an array of satellite and ground-based instruments and processing strategies. The revised heights in the subsequent papers often determined plume altitudes above the 16-18 km tropopause and into the stratosphere. Absent in our earlier report but well documented in the papers was evidence of a 16 June 2011 eruptive pulse.

Overall, Nabro erupted a total SO2 mass of at ~1.5 Tg (Clarisse and others, 2012), making the eruption the largest SO2 emitter of the 2002-2012 interval (Bourassa and others, 2013). The various papers and the technical comments have also framed debate on how and when Nabro's plume entered stratosphere.

Thermal alerts. This report does not contain any new in situ observations at Nabro. Table 1 shows MODVOLC thermal alerts during November 2011 and into 2012 on the basis of the number of days with alerts in these months. Those alerts stem from observations made with the MODIS instrument that flies on the Terra and Aqua satellites. Our previous report discussed alerts as late as 5 November 2011, but additional alerts were issued later in the month. For this table, January 2012 was the month with the largest number of days with alerts, 15 days. As of late 2014, the last posted alert was issued on 3 June 2012.

Table 1. MODVOLC thermal alerts recorded for Nabro from November 2012 through September 2014. Courtesy of MODVOLC.

Month Number of days with alerts
November 2011 11
December 2011 08
January 2012 15
February 2012 12
March 2012 07
April 2012 11
May 2012 11
June 2012 01

Although the earlier alerts may signify ongoing eruption, some of the later alerts could stem from ongoing post-eruptive thermal radiance from potentially thick lava flows. Absence of alerts could be the result of clouds masking the volcano, although that is unlikely significant in the terminal alert registered in June 2012. It also bears noting that the alerts are at a fairly high threshold.

References. Bourassa, AE, Robock, A, Randel, WJ, Deshler, T, Rieger, LA, Lloyd, ND, Llewellyn, EJ, and Degenstein, DA, 2012, Large Volcanic Aerosol Load in the Stratosphere Linked to Asian Monsoon Transport. Science 337 (6090):78-81. DOI: 10.1126/science.1219371.

Bourassa, AE, Robock, A, Randel, WJ, Deshler, T, Rieger, LA, Lloyd, ND, Llewellyn, EJ, and Degenstein, DA, 2013, Response to Comments on "Large volcanic aerosol load in the stratosphere linked to Asian Monsoon transport. Science, 339 (6120), 647, DOI: 10.1126/science.1227961.

Clarisse, L., P.-F. Coheur, N. Theys, D. Hurtmans, and C. Clerbaux, 2014, The 2011 Nabro eruption, a SO2 plume height analysis using IASI measurements, Atmos. Chem. Phys., 14, 3095-3111,DOI:10.5194/acp-14-3095-2014.

Clarisse, L., Hurtmans, D., Clerbaux, C., Hadji-Lazaro, J., Ngadi, Y., & Coheur, P. F., 2012, Retrieval of sulphur dioxide from the infrared atmospheric sounding interferometer (IASI). Atmospheric Measurement Techniques Discussions, 4, 7241-7275 [13 March 2012; revised from 2011 version] www.atmos-meas-tech.net/5/581/2012/; DOI:10.5194/amt-5-581-2012.

Fairlie, T. D., Vernier, J.-P., Natarajan, M., and Bedka, K. M., 2014, Dispersion of the Nabro volcanic plume and its relation to the Asian summer monsoon, Atmos. Chem. Phys., 14, 7045-7057, DOI:10.5194/acp-14-7045-2014, 2014.

Fromm, M, Nedoluha, G, and Charvat, Z, 2013, Comment on "Large Volcanic Aerosol Load in the Stratosphere Linked to Asian Monsoon Transport." Science 339 (6120). DOI: 10.1126/science.1228605.

Fromm, M, Kablick, G (III), Nedoluha1, G., Carboni, E., Grainger, R., Campbell, J, and Lewis, J., 2014, Correcting the record of volcanic stratospheric aerosol impact: Nabro and Sarychev Peak, Journal of Geophysical Research. Atmospheres. [Early, online version, accessed August 2014] DOI: 10.1002/2014JD021507

Pan, LL, and Munchak, LA, 2011, Relationship of cloud top to the tropopause and jet structure from CALIPSO data. Journal of Geophysical Research: Atmospheres (1984-2012) 116.D12 (2011).

Penning de Vries, M. J. M., Dörner, S., Pukite, J., Hörmann, C., Fromm, M. D., & Wagner, T. (2014). Characterisation of a stratospheric sulfate plume from the Nabro volcano using a combination of passive satellite measurements in nadir and limb geometry. Atmospheric Chemistry and Physics, 14(15), 8149-8163.

Theys, N., Campion, R., Clarisse, L., Brenot, H., van Gent, J., Dils, B., Corradini, S., Merucci, L., Coheur, P.-F., Van Roozendael, M., Hurtmans, D., Clerbaux, C., Tait, S., and Ferrucci, F.: Volcanic SO2 fluxes derived from satellite data: a survey using OMI, GOME-2, IASI and MODIS, Atmos. Chem. Phys., 13, 5945-5968, doi:10.5194/acp-13-5945-2013, 2013.

Vernier, JP, Thomason, LW, Fairlie, TD, Minnis, P., Palikonda, R, and Bedka, K M, 2013. Comment on "Large Volcanic Aerosol Load in the Stratosphere Linked to Asian Monsoon Transport." Science 339 (6120). DOI: 10.1126/science.1227817.

Information Contacts: Hawai'i Institute of Geophysics and Planetology (HIGP) MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI (URL: http://modis.higp.hawaii.edu/); and Toulouse Volcanic Ash Advisory Centre (VAAC) (URL: http://www.meteo.fr/vaac/).

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.

Eruptive History

There is data available for 1 confirmed Holocene eruptive periods.

2011 Jun 13 - 2012 Jun 3 (?) Confirmed Eruption VEI: 4

Episode 1 | Eruption Summit crater and NW flank
2011 Jun 13 - 2012 Jun 3 (?) Evidence from Observations: Reported

List of 80 Events for Episode 1 at Summit crater and NW flank

Start Date End Date Event Type Event Remarks
2011 Jun 12 2011 Jun 13 Seismicity (volcanic) According to the USGS Earthquake Hazards Program, an earthquake swarm was detected during the evening of 12 June on the border of Ethiopia and Eritrea, in the vicinity of Nabro, the most prominent of three volcanoes with large summit calderas aligned in a NE-SW direction SW of Dubbi volcano. The swarm began at 1837 with an M 5.1 earthquake. Several more were detected between M 4.3 and 5.1 over the next few hours. Two M 5.7 earthquakes at depths of 10.1 km and 9.9 km were detected at 2332 on 12 June and 0003 on 13 June, respectively.
2011 Jun 13    - - - - Explosion The Toulouse VAAC reported that an eruption from Nabro (originally attributed to Dubbi) started between 0000 and 0200 on 13 June.
2011 Jun 13    - - - - Ash Plume The Toulouse VAAC reported satellite imagery indicating a new eruption that produced an ash emission that rose to 13.7 km altitude. The plume was originally assigned to Dubbi and then revised.
2011 Jun 13 2011 Jun 14 Ash Plume The eruption plume initially rose to altitudes of 9.1-13.7 km; it was later detected at altitudes of 6.1-10.7 km. Satellite images showed the plume drifting more than 1,000 km NW, over parts of Sudan. On 14 June a detached ash cloud was detected over southern Israel according to news articles. Revised plume heights published in subsequent papers determined plume altitudes above the 16-18 km tropopause and into the stratosphere.
2011 Jun 13 2011 Jun 14 Ashfall According to the Eritrean Ministry of Information, ashfall covered hundreds of square meters. News articles stated that ash had covered a well-known mine that produces edible salt, and had contaminated food and water sources.
2011 Jun 13 2011 Jun 14 Evacuations According to the Eritrean Ministry of Information, ashfall covered hundreds of kilometers and the government evacuated area residents.
2011 Jun 13 2011 Jul 6 Fatalities According to a news article, the eruption resulted in at least seven deaths in the first few days, injured many, and displaced thousands in Eritrea, and affected about 5,000 Ethiopians living near the border. In Bidu woreda, deaths of 31 persons were reported by 6 July as a result of the volcanic ash.
2011 Jun 13    - - - - VEI (Explosivity Index) VEI 4
2011 Jun 14    - - - - Ash Plume The Toulouse VAAC reported satellite imagery indicating continuous ash emission that rose to 13.7 km altitude.
2011 Jun 14    - - - - VEI (Explosivity Index) VEI 3
2011 Jun 15 2011 Jun 20 Ash Plume Based on analyses of satellite imagery, the Toulouse VAAC reported that plumes comprised mostly of water and sulfur dioxide rose to altitudes of 6.1-7.9 km. Ash was occasionally detected near the volcano. Satellite imagery posted on MODIS Web showed a dark brown ash plume fanning out to the SW on 19 June.
2011 Jun 15 2011 Jun 20 Thermal Anomaly Multiple near-daily MODVOLC thermal alerts were issued.
2011 Jun 15    - - - - Degassing The Toulouse VAAC reported satellite imagery indicating continuous emission of mainly SO2 that rose to 10.7 km altitude and later increased to 12.2 km altitude.
2011 Jun 16    - - - - Degassing The Toulouse VAAC reported satellite imagery indicating a continuing eruption of mostly SO2 to 12.2 km altitude.
2011 Jun 17    - - - - Degassing The Toulouse VAAC reported satellite imagery indicating an emission of mostly SO2 that rose to 12.2 km altitude, and stopped during the afternoon.
2011 Jun 18    - - - - Degassing The Toulouse VAAC reported satellite imagery indicating a plume composed mostly of SO2 and water vapor that rose to 7.9 km altitude.
2011 Jun 19
(in or before)
   - - - - Lava flow A thermal satellite image acquired at night revealed a 15-km-long lava flow that had traveled NW.
2011 Jun 20    - - - - Degassing The Toulouse VAAC reported satellite imagery indicating a plume of mostly SO2 that rose to 5.5 km altitude.
2011 Jun 22    - - - - Ash Plume A satellite image showed a gas-and-ash plume rising from the caldera and drifting W.
2011 Jun 23 2011 Jul 27 Thermal Anomaly Tens of near-daily MODVOLC thermal alerts were issued.
2011 Jun 24    - - - - Ash Plume Two satellite images showed the erupting vent, plumes and emissions, and lava flows in detail. A dark ash plume rose from the vent, and at higher altitudes a plume composed of water vapor and sulfur dioxide drifted W and obscured the active lava flow.
2011 Jun 24    - - - - Ashfall Black ash deposits covered the landscape to the S and W.
2011 Jun 24    - - - - Lava flow Two satellite images show the erupting vent, plumes and emissions, and lava flows in detail. One false-color image highlighted hot areas throughout the lava flow and flow front, as well as hot material above the vent. A natural-color image showed fresh but cooled lava flows in the N part of the caldera.
2011 Jun 26    - - - - Ash Plume The Toulouse VAAC reported satellite imagery indicating weak activity producing a plume that did not exceed 6.1 km altitude.
2011 Jun 26 2011 Jun 27 Ash Plume Based on analyses of satellite imagery, the Toulouse VAAC reported that plumes rose to altitudes up to 6.1 km.
2011 Jun 29    - - - - Ash Plume A brown ash plume rose from the vent and drifted S.
2011 Jun 29    - - - - Ash Plume The Toulouse VAAC reported satellite imagery indicating an eruption that started around 0815 UTC and produced an ash plume that rose to 6.1 km altitude. The eruption stopped around 1500 UTC the next day.
2011 Jun 29    - - - - Lava flow Lava flows to the W, and within the crater (E and S of the vent), continued to be hot.
2011 Jul 4    - - - - Ash Plume The Toulouse VAAC reported satellite imagery indicating an eruption that started around 1800 UTC and produced an ash plume that rose to 6.1 km altitude. Activity ended around 2200 UTC.
2011 Jul 16    - - - - Ash Plume The Toulouse VAAc reported satellite imagery indicating an eruption that started around 1200 UTC and produced and ash plume that rose to 4.9 km altitude. Activity ended around 1500 UTC.
2011 Jul 16 2011 Jul 17 Ash Plume Based on analyses of satellite imagery, the Toulouse VAAC reported that on 16 July an ash plume from Nabro rose to altitudes below 5.5 km. A weak eruption detected on 17 July decreased through the day then appeared to have stopped.
2011 Jul 17    - - - - Ash Plume The Toulouse VAAC reported satellite imagery indicating an eruption that started around 0630 UTC and produced an ash plume that rose to 5.5 km altitude. Activity had ended by 1800 UTC.
2011 Jul 31 2011 Aug 4 Thermal Anomaly Six MODVOLC thermal alerts were issued.
2011 Aug 7 2011 Aug 11 Thermal Anomaly Six MODVOLC thermal alerts were issued.
2011 Aug 18    - - - - Thermal Anomaly Two MODVOLC thermal alerts were issued.
2011 Aug 23    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
2011 Aug 27 2011 Aug 28 Thermal Anomaly Five MODVOLC thermal alerts were issued.
2011 Aug 31 2011 Sep 1 Thermal Anomaly Three MODVOLC thermal alerts were issued.
2011 Sep 5 2011 Sep 9 Thermal Anomaly Thirteen MODVOLC thermal alerts were issued.
2011 Sep 12    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
2011 Sep 16 2011 Sep 17 Thermal Anomaly Two MODVOLC thermal alerts were issued.
2011 Sep 21    - - - - Thermal Anomaly Three MODVOLC thermal alerts were issued.
2011 Sep 25    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
2011 Sep 28    - - - - Ash Plume A small and diffuse plume rose from the vent.
2011 Sep 28    - - - - Ashfall A region of seemingly thicker black ash (that completely covered the sparse vegetation) was noted S of the crater and thinner layers of ash (with some areas of visible vegetation) flanked either side of the region.
2011 Sep 28    - - - - Lava flow According to NASA's Earth Observatory, satellite images of Nabro acquired showed heat from the vent in the central crater, and from an area 1.3 km S of the vent that indicated an active lava flow.
2011 Sep 28 2011 Oct 2 Thermal Anomaly Three MODVOLC thermal alerts were issued.
2011 Oct 5 2011 Oct 12 Thermal Anomaly Six MODVOLC thermal alerts were issued.
2011 Oct 16 2011 Oct 21 Thermal Anomaly Four MODVOLC thermal alerts were issued.
2011 Oct 25 2011 Nov 5 Thermal Anomaly Twelve MODVOLC thermal alerts were issued.
2011 Nov 10 2011 Nov 13 Thermal Anomaly Three MODVOLC thermal alerts were issued.
2011 Nov 17 2011 Nov 19 Thermal Anomaly Two MODVOLC thermal alerts were issued.
2011 Nov 28    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
2011 Dec 5    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
2011 Dec 8    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
2011 Dec 12    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
2011 Dec 19 2011 Dec 21 Thermal Anomaly Two MODVOLC thermal alerts were issued.
2011 Dec 24    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
2011 Dec 29 2012 Jan 2 Thermal Anomaly Three MODVOLC thermal alerts were issued.
2012 Jan 6 2012 Jan 18 Thermal Anomaly Eleven MODVOLC thermal alerts were issued.
2012 Jan 23 2012 Feb 1 Thermal Anomaly Seven MODVOLC thermal alerts were issued.
2012 Feb 5 2012 Feb 8 Thermal Anomaly Four MODVOLC thermal alerts were issued.
2012 Feb 12 2012 Feb 17 Thermal Anomaly Four MODVOLC thermal alerts were issued.
2012 Feb 21 2012 Feb 24 Thermal Anomaly Three MODVOLC thermal alerts were issued.
2012 Feb 28 2012 Mar 1 Thermal Anomaly Two MODVOLC thermal alerts were issued.
2012 Mar 4    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
2012 Mar 8 2012 Mar 10 Thermal Anomaly Two MODVOLC thermal alerts were issued.
2012 Mar 13    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
2012 Mar 17    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
2012 Mar 27    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
2012 Apr 2    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
2012 Apr 9 2012 Apr 11 Thermal Anomaly Two MODVOLC thermal alerts were issued.
2012 Apr 16 2012 Apr 20 Thermal Anomaly Four MODVOLC thermal alerts were issued.
2012 Apr 23    - - - - Thermal Anomaly Two MODVOLC thermal alerts were issued.
2012 Apr 28 2012 May 7 Thermal Anomaly Eight MODVOLC thermal alerts were issued.
2012 May 10    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
2012 May 14    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
2012 May 20 2012 May 21 Thermal Anomaly Two MODVOLC thermal alerts were issued.
2012 May 27 2012 May 30 Thermal Anomaly Three MODVOLC thermal alerts were issued.
2012 Jun 3    - - - - Thermal Anomaly A MODVOLC thermal alert was issued.
Deformation History

There is data available for 1 deformation periods. Expand each entry for additional details.


Deformation during 2011 Jul - 2012 Oct [Subsidence; Observed by InSAR]

Start Date: 2011 Jul Stop Date: 2012 Oct Direction: Subsidence Method: InSAR
Magnitude: Unknown Spatial Extent: 12.00 km Latitude: Unknown Longitude: Unknown

Remarks: InSAR reveals a concentric subsidence signal centered on Nabro caldera following the June 2011 eruption.

Figure (see Caption)

Best-fit model assuming Mogi and sill sources. (a) Observed ascending rate map of ground movement, white point: pixel used for time series. (b) Mogi model of deformation for ascending track. (c) Residual motion following Mogi model. (d) Sill model of deformation for ascending track. (e) Residual motion following sill model. (f) Observed descend- ing rate map of ground movement. (g) Mogi model of deformation for descending track. (h) Residual ground motion. (i) Sill model of deformation for descending track. (j) Residual ground motion. (k) Profile of ground displacement along transect N-S on Figure 3a. (l) Profile of ground displacement along transect W-E on Figure 3a. The black squares in Figures 3a and 3f show the far-field regions used to calculate noise for the Monte Carlo analysis. The red points in Figures 3b, 3d, 3g, and 3i, mark the center of the model at depth. The interferograms span 462 days for both the ascending and descending tracks.

From: Hamlyn et al. 2014.


Reference List: Hamlyn et al. 2014.

Full References:

Hamlyn, J. E., D. Keir, T. J. Wright, J. W. Neuberg, B. Goitom, J. O.S. Hammond, C. Pagli, C. Oppenheimer, J. Kendall, and R. Grandin., 2014. Seismicity and subsidence following the 2011 Nabro eruption, Eritrea: Insights into the plumbing system of an off-rift volcano. J. Geophys. Res., 119, no. 11: 8267-8282.

Emission History

There is data available for 1 emission periods. Expand each entry for additional details.


Emissions during 2011 Jun 13 - 2011 Jun 13 [3650 kt SO2 at 18 km altitude]

Start Date: 2011 Jun 13 Stop Date: 2011 Jun 13 Method: Satellite (Aura OMI)
SO2 Altitude Min: 18 km SO2 Altitude Max: 18 km Total SO2 Mass: 3650 kt

Data Details

Date Start Date End Assumed SO2 Altitude SO2 Algorithm SO2 Mass
20110613 18.0 3650.000
GVP Map Holdings

Maps are not currently available due to technical issues.

Smithsonian Sample Collections Database

There are no samples for Nabro in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.

External Sites