RESULTS OF MONITORING WORK
A) Between 18 April and 1 June 2015 the Ubinas volcano seismicity was characterized by various types of earthquakes (LP low-energy , tremors, some volcanos – tectonic VT, and hybrid). However, as the week of June 2 to 8, significant changes were observed and the number of VT earthquakes has sharply increased. Subsequently, on June 14, very energetic hybrid earthquakes were recorded. The following days and during the month of July the seismicity rose sharply , low energy explosions were recorded (0.3 MJ to 4 MJ), but in increasing numbers, with the issuance of moderate ash volumes. On July 25 at 7:03 p.m. HL explosion which reached 507 MJ of energy was recorded, being the strongest ever held in 2015. Fifteen minutes after the explosion, the fallout of ash and lapilli were observed (rock fragments 2 to 3 mm, and some up to 2 cm in diameter) in the cities of Ubinas and Escacha.
B) Between April 18 and July 16, flows of volcanic SO2 gas remained at high levels. The 17, 18 and 19 July, these flows reached the highest values in 2015, with 4969 t / d, 4872 t / day and 4927 t / d, respectively. On July 19, this flow decreased gradually until July 25 to 589 t / d, indicating that the conduits were closed after the explosion. Between 26 and 29 July these flows were below 1080 t / day.C) During the period from April to mid-June, the height of the plume of gas and ash was less than 1500 m above the top of the volcano, for later increase to 2800 m until mid-July .
On July 25 at 19:03 HL an explosion accompanied by a roar that shook the tin roofs in the town of Ubinas, located 6 km from the crater was observed. The explosion projected glowing rock fragments that have fallen to the east and southeast of the crater. Simultaneously there has been a significant release of ash and gas that rose around 4000 m high, accompanied by lightning. Within a few hours, it was reported in the city of Ubinas, ash of coarse falls (from 2 to 3 mm, and up to 1.5 cm) and sulfur gas characteristic odors.
Summary of eruptive activity:
After nearly two months of relative calm, the Ubinas volcano has shown signs of a growing increase in seismic activity and gas and ash emissions. During the second and third week of July, this increase in activity was more evident, and on July 25 an explosion took place, with calculated energy of 507 MJ, the highest recorded this year. Associated with this explosion, it was issued by the Ubinas a moderate volume of volcanic ash and gas that rose to 4000 m above the top of the volcano. The ash fell mainly on villages in eastern and southeast of the volcano, reaching distances up to 20 km. These particles can cause negative effects on human health and affect agriculture and livestock.
August 01, 2015. Ubinas, Perou :
Source : IGP / Ingemmet.
Photo : Latintimes .