Eruptive activity at Turrialba volcano (Costa Rica): Inferences from ³He/⁴He in fumarole gases and chemistry of the products ejected during 2014 and 2015

Abstract

A new period of eruptive activity started at Turrialba volcano, Costa Rica, in 2010 after almost 150 years of quiescence. This activity has been characterized by sporadic explosions whose frequency clearly increased since October 2014. This study aimed to identify the mechanisms that triggered the resumption of this eruptive activity and characterize the evolution of the phenomena over the past 2 years. We integrate 3He/4He data available on fumarole gases collected in the summit area of Turrialba between 1999 and 2011 with new measurements made on samples collected between September 2014 and February 2016. The results of a petrological investigation of the products that erupted between October 2014 and May 2015 are also presented. We infer that the resumption of eruptive activity in 2010 was triggered by a replenishment of the plumbing system of Turrialba by a new batch of magma. This is supported by the increase in 3He/4He values observed since 2005 at the crater fumaroles and by comparable high values in September 2014, just before the onset of the new eruptive phase. The presence of a number of fresh and juvenile glassy shards in the erupted products increased between October 2014 and May 2015, suggesting the involvement of new magma with a composition similar to that erupted in 1864–1866. We conclude that the increase in 3He/4He at the summit fumaroles since October 2015 represents strong evidence of a new phase of magma replenishment, which implies that the level of activity remains high at the volcano.

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

“…Previous diffuse degassing survey would have been necessary to confirm this theory. However, the occurrence of energetic phreatomagmatic eruption in October 2014, March 2015, May and September 2016 and the increase of CO 2 in the plume de Moor et al, 2016a;Rizzo et al, 2016) comforts the idea that magma established open conduits to the surface.…”

“…Other authors have provided evidence of volcanic cycles of Poás volcano (Rymer et al, 2000(Rymer et al, , 2005(Rymer et al, , 2009). But both volcanoes showed significant recent activity changes with episodes of frequent phreatic eruptions at Poás in 2006, 2011, 2014, and 2016 as reported by the Global Volcanism Program (Global Volcanism Program, 2006, 2011, 2013, 2015b, and the occurrence of phreatomagmatic eruptions at Turrialba volcano in 2010 and 2012 and frequent eruptive episodes since 2014 (Global Volcanism Program, 2010, 2012, 2013, 2015aCampion et al, 2012;de Moor et al, 2016a;Rizzo et al, 2016).…”

Plant responses to volcanically elevated CO<sub>2</sub> in two Costa Rican forests

“…Many of the data types that would be useful for this type of study can be acquired from airborne platforms, and remote sensing instruments can quickly produce the massive datasets required to provide more comprehensive answers to these questions. A recent meta-analysis showed that studies at natural CO 2 -producing springs and FACE experiments have found similar results in a variety of plant traits, which significantly strengthens the case that volcanoes are a potentially extremely valuable resource for determining plant responses to elevated CO 2 concentrations (Saban et al, 2019). While the spring studies have yielded valuable results, volcanoes could offer several advantages over springs for future studies.…”

“…Turrialba's CO 2 emissions in areas proximal to the crater were calculated at 113 ± 46 tons d −1 (Epiard et al, 2017). The Falla Ariete (Ariete fault), a major regional fault, runs northeast-southwest through the southern part of Turrialba's central edifice and is one of the largest areas of diffuse CO 2 emissions on Turrialba (Epiard et al, 2017;Rizzo et al, 2016). Atmospheric CO 2 has an average δ 13 C value of −9.2 ‰ at Turrialba, and the volcanic CO 2 released at the Ariete fault has significantly heavier δ 13 C values clustered around −3.4 ‰ (Malowany et al, 2017).…”

Carbon isotope systematics of Turrialba volcano, Costa Rica, using a portable cavity ring‐down spectrometer

“…Turrialba is upwind of the Central Valley in Costa Rica, ∼20 km from the country's densest population center of San Jose, and ∼30 km from the international airport. Eruptions from Turrialba are of concern for their direct impact on local farmland and urban centers [ Reagan et al ., ]; recent eruptions commencing on 29 October 2014 have had substantial impact on the local community and have resulted in local evacuations and airport closures [ de Moor et al ., ; Alvarado et al ., ; Rizzo et al ., ]. Turrialba has had six major phreatic and phreatomagmatic eruptions in the past 3400 years, with the last major period of activity ending in 1866 [ Reagan et al ., ].…”