eruption occurred. On May 21, 2013, at 08:52, a gas explosion widened several openings near the main crater that appeared in 2010 and 2012. In July 2013 researchers found that tremors around the area increased from about twenty earthquakes a day, to up to thirty per hour. On October 17, 2014, the quantity of tremors increased from around 50-100 a day, to 200 a day. On October 29, 2014, at around 10:10, a tremor started and kept constant, until a phreatic eruption occurred around 23:10 at the west opening that appeared in January 2012. This eruption sent a large amount of volcanic material to areas up to away. Many citizens reported ash falling on their properties and a strong odor of sulphur in the cantons of Vázquez de Coronado, Goicoechea, Moravia, Desamparados, Aserrí, Escazú, Santa Ana, Montes de Oca, Tibás, Alajuelita, Puriscal, San José in the province of San José, La Union in the province of Cartago and Santo Domingo and Heredia, in the province of Heredia. March 2015 On March 12, 2015, eruptions at around 11:00 and 14:12 sent ashes through all the Central Valley, it is regarded as the most significant activity since 1996. The Juan Suantamaría and Tobías Bolaños international airports were closed due to visibility being less than 100 meters. On March 13, 2015, an eruption occurred at 21:07. May 2015 On May 4, 2015, an eruption occurred at 15:24. May 2016 An eruption occurred on May 21, 2016. It was characterized by one resident as the largest since 2010. Ash fell as far away as the capital, San Jose, and at least 500 people went to hospitals complaining of breathing problems. Flights into San Jose were cancelled due to concerns about ash. September 2016 On September 19, at 02:54 an eruption lasting around fifteen minutes was the first event of many through the day that eventually covered the metropolitan area with ash. There were events at 11:30, 14:40, 15:34. The events continued through September 20 with an eruption at 06:20. Airports in the metropolitan area were closed. See also List of volcanoes in Costa Rica References External links Costa Rican Vulcanologic and Seismologic Observatory: Turrialba Webcam of the Vulcanological and Seismological Observatory of National University of Costa Rica. Stratovolcanoes of Costa Rica Active volcanoes Mountains of Costa Rica Geography of Cartago Province