Classification of seismic-volcanic signals

Volcanic seismology is aimed to study seismic signals originating from volcanoes, in order to discover their relationship and interactions with volcanic eruptions and seismo-tectonic processes. In particular, classification of seismic signals is a critical issue in volcanic seismology for the interpretation, learning and modelling of seismic events. An automatic pattern recognition system is useful to properly classifiy new volcanic-tectonic events —helping the experts in their daily task of interpretating seismograms— and also for detecting anomalies and discovering special events associated to eruption risk. In addition, due to the large and increasing amount of data being produced by the monitoring networks, an automatic and fast classification technique should be considered.

Nevado del Ruiz volcano:

Elevation: 5.389 m (17.784 feet)
Location: Colombia
Range: Andes
Coordinates: 4° 53' 43" N, 75° 19' 21"W
Type:Stratovolcano

Photo: Nevado del Ruiz volcano, as seen from Manizales, Colombia. 2005 (© This picture was taken by my uncle-in-law: Fernando Dávila Arias. Click to enlarge!). See more pictures from INGEOMINAS website: [1][2][3][4].

Ruiz is the northern-most historically active volcano in South America. Because of the high elevation of the summit (17.453 feet, 5.321 m), the volcano is capped by a large volume of snow and ice, its glacier has a volume of about 1200~1500 million cubic meters. Nevado del Ruiz has three craters: Arenas (the active one. Its diameter is 870 x 830 m and the depth is 247 m) and two parasite craters: Olleta (see some pictures: [1][2][3]) and Piraña.
In 1595 and 1845 summit eruptions melted snow and ice and produced mudflows that traveled tens of miles from the volcano. These mudflows were confined to the valleys that drain the volcano. The 1985 eruption of Ruiz, although only moderately explosive, produced mudflows which reached the town of Armero and killed more than 23,000 people. This eruption of Ruiz was the second mostly deadly of the century; Mount Pelee in Martinique was first, killing 29,000 people in its 1902 eruption. (Description from VolcanoWorld and INGEOMINAS website).

Galeras volcano:

Elevation: 4.276 m (14,029 feet)
Location: Colombia
Range: Andes
Coordinates: 1° 13' 43.8"N, 77° 21' 33"W
Type:Stratovolcano

Photo: Galeras volcano, as seen from Pasto, Colombia. 2006 (© INGEOMINAS - Observatorio Vulcanológico y Sismológico de Pasto). See more pictures at Galeras photo gallery.

The Galeras Volcano is an active volcano located in the southwest Colombian Andes near the border of Ecuador. The volcano has erupted more than 20 times since it was first visited by European explorers in the 16th century. One of the most recent eruptions of the volcano occurred in 1993, when nine people on an expedition to the summit were killed. The city of Pasto, Colombia, which has a population of 300,000 inhabitants, is located very close to the volcano (Description from astrographics.com).

Sample signals:
Data are collected by the seismic monitoring network of the Volcanological and Seismological Observatory at Manizales and the Volcanological and Seismological Observatory at Pasto. Nevado del Ruiz volcano is monitored by the first Observatory while Galeras volcano is monitored by the second one. The following are some examples of the signals recorded at Nevado del Ruiz volcano (sampling frequency: 100.16Hz, station: Olleta crater):

Avalanche [sample]	Distant or teleseismic earthquake [sample]
Hybrid earthquake [sample]	Icequake [sample]
Long period earthquake [sample]	Regional earthquake [sample]
Lightning [sample]	Tectonic-local earthquake [sample]
Volcanic tremor [sample]	Volcano-tectonic earthquake [sample]

People involved:

• Mauricio Orozco Alzate
• Marcelo Enrique García Ocampo
• Robert P.W. Duin
• Ricardo Henao
• Mauricio Álvarez
• Germán Castellanos Domínguez

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