Tungurahua is one of the most active volcanoes in Ecuador, and is located about 140 km south of the capital city of Quito.
Tungurahua is a steep-sided stratovolcano that towers 3 km above its northern base. Tungurahua volcano has a complex historical record which includes sudden, violent eruptions. The volcano has a diameter of 14 km.
Historic volcanic activity has occurred at the summit vent, and has consisted of strombolian to vulcanian explosions, sometimes accompanied by pyroclastic flows,
lava flows and lahars.
A sector collapse 2995 years ago left a great amphitheater and avalanche deposit of 8 cu km which traveled a distance of 15 km. The current activity of the volcano has rebuilt the cone to about 50% of the pre collapse size. Between 1400 and 2300 years ago there were high rates of lava extrusion and pyroclastic flows.
During the past 1300 years eruptive episodes were generally once per century, and commenced with lapilli emission and pyroclastic flows, followed by lava flows or lava plug in the crater. This cycle was observed in the largest historic eruptions in 1773, 1886 and 1916-1918.
Increased actvity occurred at Tungurahua volcano, Ecuador on 26th April 2011. Ash emissions reached a height of 4 km above the crater. An orange alert was issued for the volcano, and residents were evacuated from areas close to the volcano. Activity increased at the volcano on 20th April 2011. There was a widening of the crater and gas emissions were over one thousand tonnes per day.
At 8:30 am on 4th December (local time) there was a rapid increase in seismic activity at Tungurahua volcano, Ecuador. Explosions sent ash 2 km above the crater. The sound of explosions were heard at Puyo. At 9:38 am local time, pyroclastic flows were observed on the western flank of the volcano. At 9:46 am pyroclastic flows descended Vazcún gorge. Windows rattled in Guadalupe, located 14 kilometres from the volcano, and in Patate. At 10:30 (local time) several pyroclastic flows continued to flow down several drainages on the western side of the volcano (Mandur, Choglontus, La Rea). At 1:30 pm pyroclastic flows continued down some drainages on the western side of the volcano. Ashfall was reported in Pondoa and Patate. This type of eruption was unexpected in the open vent system of the volcano. From 13:45 (local time), the eruption showed a decline in intensity. A constant emission column with moderate to high ash content, reached a height of about 3 kilometres above the crater and drifted east. A pyroclastic flow was generated at approximately 14h04 (local time) and traveled about 2 miles from the crater. Shallow seismic activity continued to decline in the afternoon. At 18:17 (local time), a loud explosion heard in several nearby villages.
Tungurahua volcano in Ecuador erupted on 28th May 2010, forcing the evacuation of hundreds of people. The eruption plume rose 10 km above the crater. Ashfall was reported at the city of Guyaquil, 185 kilometers southwest of the volcano. Flights were disrupted at Guayaquil and Quito airports.
Eruptions continue at Tungurahua volcano in 2010. On 1st January as reach a height of 6 km. On 3-4 January incandescent lava was ejected from the crater.
Explosions occurred almost daily at Tungurahua volcano in June. On 23rd June, lava fountains occurred at the summit and blocks ejected from the crater rolled 1 km down the flanks. On 23rd June ash emissions reached a height of 7 km above sea level.
Eruptions in January 2008 forced the evacuation of 1000 people. Two large eruptions occurred on 6th February 2008 with ash to 47,000 ft altitude.
Eruptions continue in November 2008. Light ashfall was reported in Pillate (8 km W) and part of Riobamba (about 30 km S) on 4th November.
Phreatic eruptions began at Tungurahua volcano in August and September 1999. This was followed by magmatic activity which produced vulcanian and strombolian eruptions with ash emissions. The eruptions threatened the tourist town of Banos on the northern side of the volcano, and other villages in the area. Between October 1999 and October 2006, Tungurahua alternated between explosive periods, characterized by both Strombolian and Vulcanian activity, and relatively quiet intervals with weak steam and ash emissions or total quiescence.
On 16th February 1916 mild tremors were felt at Banos. Beginning the last week of February for 2 weeks there were underground noises heard at Tungurahua volcano. At 6am on 2nd March a large column of gas and ash was emitted, with incandescent bombs and lightning. A Formidable eruption began at 5:30 pm. Choking smell of sulphur, and a bridge was destroyed in the east. During the night explosions occurred every 2-3 minutes. Ash from this eruption reached the sea at Caráquez Bay. Complete darkness occurred on 6th February at 4pm. On 7th February a formidable eruption was preceded by a huge cannon explosion. Thousands of bombs were ejected and pyroclastic flows reached the lower part of the volcano. Activity continued until April 1916.
On 20th December 1917 pyroclastic flows, bombs and lightning, occurred for 36 consecutive hours. Explosions caused glass breakage. On 30th December 1917 at 5am a powerful explosion rattled doors and windows, and broke glass. Repeated cannon-like eruptions occurred at intervals of 5 to 8 minutes. During periods of clear weather, burning vegetation was observed.
At 18:30 hr on April 5 1918 a large eruption produced a 25 km high column. On 16th November 1918 a considerable column of ash and gas was emitted from Tungurahua volcano. Large pyroclastic flows were produced. The volcanic plume reached Quito, where fine ash fell. Small eruptions occurred up until 1925.
At 9:30 am on 11th January 1886 muffled thunder and prolonged eruption started. Column of gray smoke rose rapidly, with each eruption followed by another without interruption. The eruption column reached a height of 16 km. Volcanic storm produced thousands of lightning strikes, which persisted throughout the day and the following. Permanent underground noises. Lava flowed down NW flank. Pyroclastic flows descended several directions. By 3:30 pm darkness occurred at Puel. About 1 metre of ash was deposited at Cotala. Melting snow produced lahars which destroyed bridges atLligua, Rio Verde and Agoyán Chico. A lake was formed by damming the Patate and is about 6 km long by 300 m wide, and 30 m deep. Damage covered 25 miles around the volcano. On 25th February Tungurahua entered a period of activity much greater than before. Eruptions decreased on 3rd March and intermittent activity persisted until July 1886.
In 1773 an eruption of Tungurahua produced a large debris flow that descended the Vazcún valley, narrowly missing Baños. On 23rd April “belching fire, lightning, sand, dirt, ash, water and thick smoke” reported at the volcano. The eruption dammed Pastaza River. The eruption formed small hills called El Calvario and Panteón-barrer, and the lava flow of Juiví Grande. On 24th April Earthquakes and subterranean noises continued.