Purace Volcano in Colombia Marks one Month on Orange Alert with Intense Activity
A month ago, the alert status of the Purace volcano changed from yellow to orange. The volcanic chain of which it is part, Los Coconucos, in the department of Cauca, remains active and keeps the country in a state of constant expectation.
For this reason, the Colombian Geological Service (SGC) once again referred to the hazard map, a tool containing the keys to risk management based on scientific information.
The SGC recalls that the Purace volcano is located in the department of Cauca, 27 kilometers southeast of Popayan, and has a monitoring network made up of 121 stations, 71 of them telemetric, and around 50 sampling points for gases, hot springs and deformation measurements, among others.
The latest version of the Purace volcano hazard map, prepared by SGC scientists, dates from 2014 and has been shared with departmental, municipal and Indigenous authorities, especially the councils of Purace, Paletara and Coconuco, since the area of high and medium hazard influence is mainly Indigenous and peasant.
The map establishes that there are three hazard zones in the event of an eruption of the Purace volcano: high (red), medium (orange) and low (yellow). The boundaries between the three are transitional because volcanic phenomena do not behave uniformly, which is why they are represented with dashed lines.
High hazard zone
It comprises the area closest to the crater, part of the municipalities of Popayan and Purace, especially their rural districts of Campamento, Pululo, Alto Anambio, Chapio, Tabio, Hispala, Cristal, Chiliglo, Patugo and Cobalo. It also includes the basins of the Cocuy, San Francisco, Vinagre and Anambio rivers, and the Agua Blanca creek, among other tributaries of the Cauca River.
In this high hazard zone, during an eruption of the Purace volcano, phenomena such as the fall of pyroclasts and pyroclastic density currents could occur (a mixture of hot gases, ash and rocks that could descend at hundreds of kilometers per hour down the slopes of the volcano), traveling distances of around 10 km from the emission source.
In the same high hazard zone, mudflows could also occur, traveling through the valleys of rivers and streams that originate at the volcano; lava flows that would affect the highest parts of the volcano; bombs and blocks emitted as ballistic projectiles (fragments expelled from the volcano at high speed) with diameters of centimeters or even meters, which may be solid (blocks) or fragments of molten rock that cool upon contact with the air (bombs). Shock waves and earthquakes that could be felt could also occur.
Medium and low hazard zones
But things change in the medium hazard zone, where rural districts such as Hispala and Hato Viejo (in the municipality of Purace); Alto Pasares (in Popayan) and rural districts of the municipality of Timbio, among others, are located.
There, phenomena such as the fall of pyroclasts with accumulations between 10 mm and 1 cm could occur; ballistic projectiles with diameters between 6 and 20 cm; shock waves generated by explosive eruptions, and earthquakes that could be felt.
The low hazard zone includes part of the municipalities of Popayan, Purace, Totoro and El Tambo, among others. In these places, ash could fall with accumulations of 1 cm to 5 mm; as well as seismic activity and shock waves due to the explosive activity of the volcano.
To prepare this map, SGC experts analyzed the eruptive history of the Purace volcano over the last 10,000 years, and currently are integrating the hazard map of the Purace, Curiquinga and Piocollo volcanoes, which are part of the Los Coconucos volcanic chain.
Based on this knowledge, strategies can be developed for proper risk management, the response of different local, departmental and national authorities can be prepared, and territorial planning policies can be guided to preserve the lives of inhabitants living in volcanic influence zones.
The volcano may experience temporary variations
The SGC, through the Popayan Volcanological and Seismological Observatory, monitors this Purace volcano 24/7 and promptly reports any change in its status through its website, social media and permanent communication with local, regional and national authorities.
According to the SGC’s most recent report, several of the monitored parameters have reached some of the highest levels recorded during recent weeks, which is why authorities maintain permanent surveillance of the volcano’s evolution.
“A predominance of seismic signals associated with fluid dynamics in the volcanic conduits remains on record, especially tremor-type signals (TR), which continue to be located beneath the crater of the Purace volcano at depths of less than 1 km,” stated the latest communiqué issued by the agency.
In recent reports, around 80 earthquakes were recorded, located between 10 and 15 kilometers northeast of the volcano, with depths ranging between 7 and 11 kilometers. In addition, a slow process of ground deformation persists in the area between the Purace, Piocollo and Curiquinga volcanoes.
The SGC stated that the volcano’s activity may experience temporary variations, meaning that at certain times it could decrease compared with the levels observed in previous days or weeks. But a temporary reduction does not necessarily mean that Purace has returned to a stable state, so monitoring is maintained for any change in its behavior.
The SGC recommends that the community avoid approaching the craters of the Purace, Piocollo and Curiquinga volcanoes, as well as the headwaters of the rivers that originate in these areas. The agency warned that sudden emissions of gases and ash may occur there, in addition to the ejection of rock fragments, and therefore urged people to maintain precautionary measures.