Global Volcanism Program

17 December-23 December 2008

Based on analysis of satellite imagery, the Washington VAAC reported that on 17 December a gas plume with possible ash rose to altitudes of 5.3-6.1 km (17,500-20,000 ft) a.s.l.

Sources: Washington Volcanic Ash Advisory Center (VAAC)

Available Weekly Reports

17 December 2008 Back to Top

Based on analysis of satellite imagery, the Washington VAAC reported that on 17 December a gas plume with possible ash rose to altitudes of 5.3-6.1 km (17,500-20,000 ft) a.s.l.

Sources: Washington Volcanic Ash Advisory Center (VAAC)

26 November 2008 Back to Top

Based on analysis of satellite imagery, the Washington VAAC reported that on 2 December a plume possibly containing some ash drifted less than 20 km SW.

Sources: Washington Volcanic Ash Advisory Center (VAAC)

29 October 2008 Back to Top

Based on analysis of satellite imagery, the Washington VAAC reported that on 4 and 5 November possible diffuse ash and steam plumes from Masaya drifted SW and S.

Sources: Washington Volcanic Ash Advisory Center (VAAC)

8 October 2008 Back to Top

Based on pilot observations, the Washington VAAC reported that on 9 October an ash plume from Masaya rose to an altitude of 4.6 km (15,000 ft) and drifted NNE.

Sources: Washington Volcanic Ash Advisory Center (VAAC)

10 September 2008 Back to Top

Based on analysis of satellite imagery, the Washington VAAC reported that plumes emitted from Masaya on 10 and 12 September possibly contained ash. Plumes drifted ENE on 10 September.

Sources: Washington Volcanic Ash Advisory Center (VAAC)

13 August 2008 Back to Top

Based on analysis of satellite imagery, the Washington VAAC reported that a diffuse steam plume from Masaya drifted WSW on 12 August and a gas plume was detected on 18 August. Both plumes possibly contained ash.

Sources: Washington Volcanic Ash Advisory Center (VAAC)

18 June 2008 Back to Top

INETER reported that on 18 June, an explosion from Masaya produced an ash-and-gas plume. Local people felt the explosion and reported that the plume was dark in color.

Sources: Instituto Nicaragüense de Estudios Territoriales (INETER)

23 April 2008 Back to Top

Based on observations of satellite imagery and pilot observations, the Washington VAAC reported that an ash plume from Masaya rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted SW on 29 April.

Sources: Washington Volcanic Ash Advisory Center (VAAC)

19 December 2007 Back to Top

Based on observations of satellite imagery, the Washington VAAC reported that a small and diffuse plume from Masaya drifted SW on 24 December. Changes in seismic signals correlated with the emission. The plume possibly contained ash.

Sources: Washington Volcanic Ash Advisory Center (VAAC)

13 June 2007 Back to Top

The Washington VAAC reported that a plume from Masaya composed of little to no ash was visible on satellite imagery on 12 June.

Sources: Washington Volcanic Ash Advisory Center (VAAC)

6 June 2007 Back to Top

The Washington VAAC reported a plume from Masaya composed of little to no ash was visible on satellite imagery on 9 June drifting W.

Sources: Washington Volcanic Ash Advisory Center (VAAC)

25 April 2007 Back to Top

The Washington VAAC reported a steam plume from Masaya, visible on satellite imagery and a web camera, drifted WSW on 26 April.

Sources: Washington Volcanic Ash Advisory Center (VAAC)

30 June 2004 Back to Top

On 4 July at 0615, a narrow plume of steam and/or ash from Masaya was visible on satellite imagery extending to the SW. By 0715 the plume extended ~12 km from the summit.

Sources: Washington Volcanic Ash Advisory Center (VAAC)

1 October 2003 Back to Top

A pilot reported seeing an eruption cloud from Masaya on 4 October at 0731 at a height of ~4.6 km a.s.l. Satellite imagery showed a white plume emanating from the volcano, but there were no indications of ash, suggesting that the plume was composed mainly of gas and steam.

Sources: Washington Volcanic Ash Advisory Center (VAAC)

23 May 2001 Back to Top

The Washington VAAC reported that Masaya may have erupted on 23 May at ~1300. Ground observations from the capital city of Managua, 20 km NW of the volcano, indicated that there was a reduction in visibility to the SE of the city due to volcanic "smoke" and steam. The presence of the ash cloud could not be confirmed on satellite imagery due to thunderstorms in the area.

Sources: Washington Volcanic Ash Advisory Center (VAAC)

25 April 2001 Back to Top

INETER personnel reported that volcanic activity at Masaya decreased following the 23 April explosion. Small explosions were observed on 24 and 25 April, but by 27 April only the continuous emission of gas at normal levels was observed with few episodes of strong degassing. Likewise, after the 23 April explosion the level of SO2 emission decreased and normal levels of seismic activity were recorded. INETER warned that further explosions may occur that could affect areas near the crater (within ~500 m).

A tourist at the scene during the 23 April explosion stated that injuries were more serious than was reported either here or in news accounts. Over 100 tourists were near the crater when the explosion occurred, including infants and elderly persons. At least 15 people sustained injuries (bruises and cuts) and one person suffered a broken arm.

Sources: Instituto Nicaragüense de Estudios Territoriales (INETER)

18 April 2001 Back to Top

At 1426 on 23 April a small explosion at Masaya's Santiago crater lasted for ~2 minutes and occurred in three phases. During the first phase volcanic gas under high pressure was explosively released and created a new vent in the bottom of Santiago crater. The eruption sent rock fragments up to 60 cm in diameter as far as 500 m from the crater. Several vehicles parked at a visitors platform near the crater were damaged by the ejecta and one person suffered minor injuries. During the second and third phases a mixture of hot volcanic gas, pieces of lava, and ash ignited dry vegetation near the crater. INETER personnel who monitored the seismic activity before the eruption and scientists from Cambridge University who were working in the crater one hour before the eruption did not notice any unusual activity at the volcano. INETER personnel monitored the volcano after the eruption and found that several small explosions, gas outbreaks, and minor collapses of the crater wall occurred. They warned that further explosions may occur that could affect areas near the crater (within ~500 m).

Sources: Instituto Nicaragüense de Estudios Territoriales (INETER) , Associated Press

Summary of eruption dates and Volcanic Explosivity Indices (VEI).

Start Date	Stop Date	Eruption Certainty	VEI	Evidence	Activity Area or Unit
2008 Jun 18	2008 Dec 17	Confirmed	1	Historical	Santiago
2006 Aug 4	2006 Oct 25 (?)	Confirmed	1	Historical	Santiago
2005 Mar 4 (?)	2005 Mar 30 (?)	Confirmed	1	Historical	Santiago
[ 2004 Jul 4 ]	[ 2004 Jul 4 ]	Uncertain	1		Santiago
2003 Sep 22 (in or before)	2003 Dec 12 (?)	Confirmed	0	Historical	Santiago
2001 Apr 23	2001 Apr 25 (?)	Confirmed	1	Historical	Santiago
1999 Nov 22	2000 Mar 2 (?)	Confirmed	1	Historical	Santiago
1998 Sep 14	1998 Sep 14	Confirmed	1	Historical	Santiago
1997 Jun 3 (?)	1997 Nov 17	Confirmed	1	Historical	Santiago
1996 Dec 5	1996 Dec 5	Confirmed	1	Historical	Santiago
1993 Jun 16	1994 Nov (in or after)	Confirmed	1	Historical	Santiago
1989 Feb 20	1989 Nov	Confirmed	1	Historical	Santiago
1987 Feb 15	1987 Feb 22 (in or after)	Confirmed	1	Historical	Santiago
1965 Oct 10 (?)	1985 Apr (?)	Confirmed	0	Historical	Santiago
1948 Sep	1948 Sep	Confirmed	1	Historical	Santiago
1946 Jun	1947 Dec (?)	Confirmed	0	Historical	Santiago
1925 Apr	Unknown	Confirmed	2	Historical	Santiago
1919	1924	Confirmed	2	Historical	Santiago
1918 Jan	Unknown	Confirmed	1	Historical	Santiago
1913 Jul 12	Unknown	Confirmed	1	Historical	Santiago
1906 Jan 2	1906 Jan 9 (in or after)	Confirmed	2	Historical	Santiago and upper NE flank near El Pelón
1904 May	1904 Jun	Confirmed	2	Historical	Santiago
1902 Jul 15	1903 Nov	Confirmed	2	Historical	Santiago
1858 Nov 10	1859 Mar 27	Confirmed	2	Historical	Santiago, San Pedro
[ 1858 Apr ]	[ Unknown ]	Uncertain
1856 Dec	1857 Jan	Confirmed	2	Historical	Santiago or San Pedro
1853 Apr 9 (?)	1853 Sep 15 (in or after)	Confirmed	1	Historical	Santiago
1852 Jun	1852 Jul	Confirmed	2	Historical	Between Masaya and Nindirí Craters
[ ~~1775~~ ]	[ ~~Unknown~~ ]	Discredited
1772 Mar 16	1772 Mar 25 (?)	Confirmed	2	Historical	North side of Old Masaya Crater
1670	Unknown	Confirmed	3	Historical	Nindirí
[ 1613 ]	[ Unknown ]	Uncertain	0		Nindirí
[ 1586 ]	[ Unknown ]	Uncertain	0		Nindirí
1570	Unknown	Confirmed	0	Historical	Nindirí
1551	Unknown	Confirmed	0	Historical	Nindirí
1524	1544 (?)	Confirmed	0	Historical	Nindirí
150 (?)	Unknown	Confirmed	5	Tephrochronology	Masaya Tuff
170 BCE ± 100 years	Unknown	Confirmed	5	Radiocarbon (uncorrected)	Masaya Triple Layer
4050 BCE (?)	Unknown	Confirmed	6	Tephrochronology	NW of caldera, San Antonio Tephra

Masaya is one of Nicaragua's most unusual and most active volcanoes. Masaya lies within the massive Pleistocene Las Sierras pyroclastic shield volcano and is a broad, 6 x 11 km basaltic caldera with steep-sided walls up to 300 m high. The caldera is filled on its NW end by more than a dozen vents that erupted along a circular, 4-km-diameter fracture system. The twin volcanoes of Nindirí and Masaya, the source of historical eruptions, were constructed at the southern end of the fracture system and contain multiple summit craters, including the currently active Santiago crater. A major basaltic plinian tephra was erupted from Masaya about 6500 years ago. Historical lava flows cover much of the caldera floor and have confined a lake to the far eastern end of the caldera. A lava flow from the 1670 eruption overtopped the north caldera rim. Masaya has been frequently active since the time of the Spanish Conquistadors, when an active lava lake prompted attempts to extract the volcano's molten "gold." Periods of long-term vigorous gas emission at roughly quarter-century intervals cause health hazards and crop damage.