Masaya Volcano

Masaya volcanic complex is nested in the older Masaya (or El Ventarron) Caldera which extends 11.5 by 6 km in a NW orientation, parallel to the axis of the central american volcanic chain. The SE quarter of the caldera is filled with the waters of Lake Masaya. Masaya volcanic complex (hereafter "Masaya") is approximately circular, with a diameter of about 3.5 km and contains a number of collapse craters and small cinder cones. It rises to a height of 550m a.s.l., with the caldera rim being about 100m higher at its highest point. Masaya has a relatively low aspect ratio and is thus considered to be a shield volcano. Historical eruptions have been largely effusive, yet the volcano is capable of powerful explosive activity which could pose a major threat to people living in the Managua, the capital of Nicaragua, which is only about 20 km to its northwest. This is in particular the case in view of the fact that pyroclastic surge deposits have been found in the location of present-day Managua. These surges would have likely been fatal for anybody caught up in them. It is thought that at least 3 major explosive eruptions occurred in the last about 6000 years, emplacing the San Antonio Tephra (6 kA), the Masaya Triple Layer (2.1 kA) and the Masaya Tuff (1.8 kA). The volcano thus represents a significant hazard. (Perez and Freundt 2006, GSA special papers v. 412, p.189-207). The driving force of these explosive eruptions was probably access of external water to the magmatic system.

Dawn view of Santiago crater of Masaya Volcano with lava lake inside	Santiago crater of Masaya Volcano with lava lake inside

Lava lake (about 30m wide), April 2016	Turbulent lava lake (April 2016)

Historic activity has been focussed on the Nindiri and Masaya craters. First records of the activity of Masaya (and Momotombo) volcanoes were made in 1525, following the Spanish Conquest of the area. The Spanish were particularly impressed by the large lava lake residing in the Nindiri crater at the time and some considered it to represent the mouth of hell. The lava lake in Nindiri crater gradually filled the crater and eventually overflowed in 1670, emplacing a lava flow covering over 2 sq. km. Subsequently, the floor of the Nindiri crater has subsided and formed two large pit craters, San Pedro in its western side and the currently active Santiago crater (formed in 1859) at its eastern side. Masaya crater last erupted in 1772, when a fissure opened half-way up its NE flank and over a period of 8 days, lava flows extended 7 km north (exiting the caldera) and 4 km to the SE, where the lava entered Lake Masaya. The lava flows covered an area of 7.5 sq. km and had an estimated volume of 22.5 million cubic meters.

1670 Overflow	1670 Overflow

1772 Flow field	Lake Masaya, reached by 1772 lava

About 6000 years ago, the first of several recent Plinian basaltic eruptions at Masaya appears to have taken place. The San Antonio tephra deposits suggest a series of eruptions, initially magmatic, later interupted by phreatomagmatic pulses and then essentially violently phreatomagmatic in nature (Rose, 2006. "Volcanic Hazards in Central America"; Perez-Fernandez, PhD thesis, Kiel Univ. 2007). The deposits have a volume of about 14 cubic km.

The prehistoric footprints of Acahualinca which were formed in tephra layers attributable to Masaya volcano (about 2100 years ago. Note: other authors postulate an age of about 6000 years based on C dating of underlying soil deposits) are further testimony to the ability of the volcano to erupt violently. The footprints were formed in the so-called Masaya Triple Layer (MTL) deposits from a violent multi-episodic eruption of Masaya involving several Plinian events (Schminke et al. 2009. Bull Volcanol. 71, p.479-493). It is thought that the group of 15 people was fleeing the eruption and walked over moist but viscous phreatomagmatic deposits from an early phase of the eruption. The material rapidly solidified (lithified) and was then overlain by deposits from subsequent episodes of the same eruption.

The sequence of events during the eruption has been reconstructed by analysis of its deposits (Perez et al. 2008. J. Volc. Geotherm. Res. 179, p.191-205). Briefly, the MTL eruption started with explosive phreatomagmatic / magmatic activity which increased in intensity and fluctuated over time. It is thought that the eruption had at least two magmatic Plinian phases and three Phreatoplinian phases (the last of which being the most powerful and essentially ending the eruption). Eruption column heights from 15-32 km are estimated from the deposit distributions. The volume of basaltic / basaltic-andesitic tephra deposited by the series of eruptions is estimated at 3.4 cubic km (1.8 km3 DRE). The eruptions are thought to have taken place over a period of weeks or months during the dry season.

A further eruption about 300 years later produced the Masaya Tuff and Ticuantepe Lapilli deposit and has an even greater volume of up to 10 cubic km (Perez-Fernandez, PhD thesis, Kiel Univ. 2007). The Masaya Tuff was deposited in part by dangeous pyroclastic surges extending as far as 30 km from the volcano. It has been proposed that the Masaya Tuffs may have been formed during the caldera forming eruption. However, the caldera may be far older, since layers within the current craters have been dated far before the three most recent Plinian eruptions and are unlikely to have withstood a major subsidence associated with caldera formation on the scale of the El Ventarron caldera intact.

In the last decades activity at Masaya has been relatively low. Gas emissions have nevertheless been significant and lead to damage of vegetation downwind. Indeed, the volcano is considered to have had several (4-10) year long increased degassing phases at intervals of 20-25 years in the last 100 years. Lava lakes were found in Santiaguito crater for long periods, yet often were deep inside vents and thus not visible from the crater rim. The location of active vents has changed over time. The lava lake documented on this page is considered to have formed on December 11-12, 2015. At the end of february there were 3 distinct vents with lava lakes in them, yet only one large vent was visble in April during the visit.

There have been numerous relatively minor explosive events in the last decades with some larger explosions expelling bombs and ash beyond the rim, the most notable in 2001 damaging vehicles at the crater rim car park and resulting in numerous minor injuries.

Santiago crater with pit and active lava lake within	Pit with lava lake

Floor of pit with lava lake	Wall of pit with blocked vent	Blocked vent

SE wall of Santiago crater	Wall shows layered lava deposits	Old cinder cone embedded in wall of Santiago crater

View over Nindiri crater to San Pedro crater (left back)	Nindiri Crater viewed from SE

Unstable section of Nindiri crater overhanging Santiago crater	Rock formations in side of Nindiri crater

View to SE with San Pedro Crater in foreground	S wall of San Pedro crater

West rim of San Pedro crater, El Ventarron rim behind	San Pedro crater, Santiago crater degassing behind	View over San Pedro to glowing Santiago crater at dusk

San Pedro with degassing Santiago crater	Inactive Masaya crater

MASAYA VOLCANO LAVA LAKE VIDEO AND TIMELAPSE (APRIL 2016):

Lava lake viewed from NE near car park	Lava bubbles in lake	Big lava bubble bursting

Lava lake viewed from S rim of Santiago crater	Vigorous lava lake activity

	Vigorous lava lake activity

Masaya volcano has long fascinated people in its vicinity. The paper by Viramonte and Incer-Barquero (J. Volc. Geotherm. Res. 176, p.419-426) summarizes interaction of local people in pre- and post-Spanish Conquest times. As with many other volcanoes, the indiginous people considered it to be a god. This apparently resulted in sacrifice of children and maidens in times of drought in the hope of obtaining rainfall. These were possibly not the only people thrown into the volcano, since it is rumored that during the final months of the Somoza dictatorship (in 1979) the National Guard dropped political prisoners into the volcanoes Santiago crater from helicopters. The prisoners were held at the nearby Coyotepe Prison (La Fortaleza El Coyotepe). However, it is not clear if bodies of deceased prisoners were disposed of in this manner, if live prisoners were thrown in, or whether there is any truth in these stories at all.

After the Spanish conquest, some saw the volcano as a "Mouth of Hell", whilst others were convinced that the lava lake was full of gold. The latter view led to the first descent into the crater in 1538 by Friar Blas del Castillo and later to the recovery of samples using an iron container. In spite of the lack of Gold in the samples, the obsession with the volcanoes alleged gold continued for many years.

Visitor Information

Masaya volcano is located about 30 minutes drive from the capital Managua. Masaya, is located in its own National Park, the first in Nicaragua (opened 1979), and visitors should inform themselves about any access restrictions (especially during eruptive phases) before visiting. The park has a visitor center providing information on the volcano and flora and fauna in the park.When the park is open, it is possible to view the main craters from a car-park located only a few meters from the rim. Cars have to be parked facing away from the crater so that in the event of an explosive eruption it will be possible to evacuate the car park quickly. On 23.04.2001, an explosive eruption associated with the opening of a new vent threw numerous hot volcanic bombs onto the rim and damaged several cars and buses at the parking lot, also causing several small fires. The roof of one bus was penetrated by a bomb which ended on an empty seat. A number of tourists suffered minor injuries from falls as they fled and impact of small ballistics.

Nicaragua has a number of active volcanoes and is thus a very interesting destination for people with an interest in geology. These include Momotombo, Telica, Conception, Cerro Negro, San Cristobal, Mombacho and Cosiguina, to name but a few.

The Nicaraguan volcanoes are monitored by INETER (Instituto Nicaraguense de Estudios Territoriales) which is also responsible for monitoring general seismic activity and tsunami warnings. The INETER website is a good source of information for anybody wishing to visit the active volcanoes within the country.

Headquarters of INETER in Managua	Inside one of INETER volcano monitoring rooms

Managua city, dangerous Chiltepe volcano on horizon	Laguna de Tiscapa and remains of Presidential Palace destroyed by 1972 earthquake

Vulture circling in hot air above vent	National Park Entrance	Parrots living in inner crater wall

Photographers on rim of Santiago crater	Masaya illuminating the night sky, view from Restaurant Mirador La Vista del Angel

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