Галерастың жанартау әрекеті мен қауіпсіздік шаралары

Volcanic mountain in Colombia

Galeras has been an active volcano for at least a million years, with andesite as the dominant product. Elements in the media made the event controversial by suggesting the expedition leader, geologist Stanley Williams, who survived along with four others, had ignored safety procedures. A prediction had been made three days before the eruption based on B Type activity seen on a seismograph. Seismic B types had been used successfully to predict eruptions on other volcanoes. However, the prediction was based simply on the one seismographic printout viewed in the light of previous history of Galeras, without any additional scientific measurements showing any serious activity within the volcano.

Activity at a low level has continued at Galeras, with small explosions occasionally dusting nearby villages and towns with ash. The volcano has continued to be well studied, and predictions of eruptions at the volcano have improved. One phenomenon, which seems to be a reliable precursor to eruptive activity, is a low frequency seismic event known as a tornillo event. These have occurred before about four fifths of the explosions at Galeras, and the number of tornillo events recorded before an eruption is also correlated with the size of the ensuing eruption. More than 100 minor tremors were felt during a major eruption in April 2002, although no damage or injury was reported. An eruption in November 2005 forced an evacuation of the dangerous area surrounding the volcano, and about 9,400 people from nearby villages (most of them farmers) were ordered to leave. The city of Pasto, about from the volcano, was blanketed by a layer of ash after the volcanic explosion, forcing the residents to don goggles and face masks. Numerous minor tremors and ash emissions since March 2006 culminated on 12 July 2006 in three explosive eruptions, producing an ash and gas column reaching an altitude of Rock falls and pyroclastic flows were reported from towns as distant as Consacá, west of the main crater. The Colombian government has repeatedly ordered evacuations to temporary shelters, of more than 8500 people residing in the highest risk areas surrounding the volcano, with hopes of eventual assistance toward permanent relocation. On January 17, 2008, the volcano erupted around 20:06 (local) (01:06 UTC). There were no immediate reports of injuries or serious property damage. Later the experts confirmed partial damage in the national and local TV towers. Then, on February 14, 2009, the volcano erupted around 19:10 (local) (00:10 UTC). Some 8,000 residents were evacuated, and there were no immediate reports of injuries or serious property damage. As in 2005, the city of Pasto was blanketed by a layer of ash after the volcanic explosion (due to the direction of the wind). The local authorities ordered two water treatment plants near Galeras to shut down. On March 13, 2009, Galeras erupted twice at around 15:55 and 17:00 (local time). Ash fell on Pasto and some other towns near the volcano, where an evacuation was ordered but reportedly ignored. No injuries or damage were reported.

The volcano erupted on January 3, 2010, forcing the evacuation of 8,000 people. This was the 10th such eruption of the volcano in the preceding 12 months, and the first of 2010. Colombian authorities also stated that it could remain volatile in the weeks to come. Galeras erupted again on August 25, 2010 with an ash plume visible in the air. The eruption, which was described as non explosive, caused authorities to raise an alert for neighbouring towns. This volcano is monitored by the Deep Earth Carbon Degassing Project.