Monitoring Quiescent Volcanoes by Diffuse CO2 Degassing: Case Study of Mt. Fuji, Japan

Abstract

Absrtract-Since the 8th century, more than seventeen eruptions have been recorded for the Mt. Fuji volcano, with the most recent eruption occurring in 1707 (Hoei eruption). For the past 300 years the volcano has been in a quiescent stage and, since the early 1960s, has exhibited neither fumarolic nor thermal activity. However, the number of low-frequency earthquakes with a hypocentral depth of 10-20 km increased significantly beneath the northeastern flank of Mt. Fuji in 2000-2001, suggesting a possible resumption of magmatic activity. In this study, diffuse CO 2 efflux and thermal surveys were carried out in four areas of the volcano in 2001-2002 in order to detect possible signs of the upward movement of deep magma. At all survey points, the CO 2 efflux was below the detection limit with the exception of a few points with biological CO 2 emission, and ground temperatures at a depth of 20-30 cm were below ambient, indicating no surface manifestations of gas or heat emission. Should magma rise into the subsurface, the diffuse CO 2 efflux would be expected to increase, particularly along the tectonically weakened lineation on the Mt. Fuji volcano, allowing for the early detection of pre-eruptive degassing.

Relationship between Diffuse CO2 Degassing and Volcanic Activity. Case Study of the Poás, Irazú, and Turrialba Volcanoes, Costa Rica

“…By 2012, diffuse degassing had decreased to 0.9 ± 0.5 t/d. By linking these observations, we propose that Poás was at increased diffuse degassing stage (stage 2 in Notsu et al, 2006) …”

“…In our case, Turrialba volcano has experienced a reawakening process which has lasted ∼20 years (Martini et al, 2010;de Moor et al, 2016a) and Poás' activity is particularly variable (Fischer et al, 2015;de Moor et al, 2016b) and seems to have stages of enhanced volcanic activity and stages of quiescence that alternate every 6-12 years (Rymer et al, 2000(Rymer et al, , 2005(Rymer et al, , 2009. Diffuse degassing monitoring could thus be an interesting tool for long term monitoring (Allard et al, 1991;Chiodini et al, 1996Chiodini et al, , 1998Chiodini et al, , 2001Giammanco et al, 1998;Hernández et al, 1998Hernández et al, , 2001Melián et al, 2001Melián et al, , 2010Salazar et al, 2001;Shimoike et al, 2002;Hernández Perez et al, 2003;Carapezza and Granieri, 2004;Galindo et al, 2004;Lewicki et al, 2005;Notsu et al, 2006;Werner and Cardellini, 2006;Carapezza et al, 2009;Viveiros et al, 2010;Peltier et al, 2012;Werner et al, 2014).…”

“…Notsu et al (2006) sampled CO 2 diffuse degassing data on the Fujisan volcano (Japan) and compared them with observations from other volcanoes (for example Mammoth Mountain, USA). Notsu et al (2006) make the hypothesis that magma intrusion to shallow levels might lead to an increase in active degassing but a dramatic decrease in diffuse degassing.…”

“…Notsu et al (2006) sampled CO 2 diffuse degassing data on the Fujisan volcano (Japan) and compared them with observations from other volcanoes (for example Mammoth Mountain, USA). Notsu et al (2006) make the hypothesis that magma intrusion to shallow levels might lead to an increase in active degassing but a dramatic decrease in diffuse degassing. This idea is in accordance with observations made at the Usu-san volcano where a strong decrease in CO 2 diffuse degassing was observed after the start of the 2000-2001 eruption as mentioned above Notsu et al, 2006).…”

“…Notsu et al (2006) make the hypothesis that magma intrusion to shallow levels might lead to an increase in active degassing but a dramatic decrease in diffuse degassing. This idea is in accordance with observations made at the Usu-san volcano where a strong decrease in CO 2 diffuse degassing was observed after the start of the 2000-2001 eruption as mentioned above Notsu et al, 2006). If such a hypothesis is correct, this may lead to interesting and complementary applications in terms of volcanic monitoring.…”