The 2007 eruptions and caldera collapse of the Piton de la Fournaise volcano (La Réunion Island) from tilt analysis at a single very broadband seismic station

Abstract

Seismic records from La Réunion Island very broadband Geoscope station are investigated to constrain the link between the 2007 eruptive sequence and the related caldera collapse of the Piton de la Fournaise volcano. Tilt estimated from seismic records reveals that the three 2007 eruptions belong to a single inflation-deflation cycle. Tilt trend indicates that the small-volume summit eruption of 18 February occurred during a phase of continuous inflation that started in January 2007. Inflation decelerated 24 days before a second short-lived, small-volume eruption on 30 March, almost simultaneous with a sudden, large-scale deflation of the volcano. Deflation rate, which had stabilized at relatively low level, increased anew on 1 April while no magma was erupted, followed on 2 April by a major distal eruption and on 5 April by a summit caldera collapse. Long-term tilt variation suggests that the 2007 eruptive succession was triggered by a deep magma input.

Rift zones and magma plumbing system of Piton de la Fournaise volcano: How do they differ from Hawaii and Etna?

“…This shallow system, which is intermittently recharged by deep magmas Fontaine et al, 2014), feeds short-lived eruptions in the Enclos Fouqué caldera that are preceded by an increase in the shallow seismicity and summit inflation Roult et al, 2012). Geophysical and geochemical data suggest that the shallow magma path is characterised by several levels of magma storage mostly organised in small pockets/sills rather than in a single large and chemically zoned magma reservoir (Albarède et al, 1997;Prôno et al, 2009;Massin et al, 2011;Di Muro et al, 2014).…”

Seismic anisotropy and its precursory change before eruptions at Piton de la Fournaise volcano, La Réunion

“…This eruption was preceded by widespread flank movement occurring with injection of magma a few days prior to the eruption [ Clarke et al ., ]. Eruption of shallow‐seated magmas (above sea level) and part of the intrusive olivine‐rich complex was triggered by a new input of deeper magma [ Di Muro et al ., ; Fontaine et al ., ]. In general, the extrusion of shallow‐seated magmas at PdF is triggered by magma emplacement at greater depths (Figure ).…”

Collapse-driven large eruptions

“…In four of the five caldera collapses that have been documented instrumentally, little or no eruptions occurred within the caldera. These are (1) the 1912 caldera collapse in Katmai in Alaska (Wood and Kienle, 1992;Hildreth and Fierstein, 2012); (2) the 1968 caldera collapse in Fernandina in the Galapagos (Filson et al, 1973); (3) the 2000 collapse of Myiakejima in Japan (Geshi et al, 2002); and (4) the 2007 collapse of Piton de la Fournaise in Reunion (Fontaine et al, 2014). Only the 1991 collapse of Pinatubo in the Philippines was associated with a moderate eruption at the site of the caldera, the magma-volume involved being about 4 km 3 (Newhall et al, 1997).…”

“…The caldera volume at Katmai, however, is 5-6 km 3 , and thus much smaller than the estimated magma volume. Similarly, there were dyke intrusions and small eruptions outside the calderas during the collapses in Myiakejima (Geshi et al, 2002) and Piton de la Fournaise (Fontaine et al, 2014), but none is known in association with the collapse of Fernandina.…”