Tha autors od this study apply a template matching method to detect and locate pre-eruptive earthquakes at Piton de la Fournaise volcano in 2014 and 2015. This approach enabled the detection of many events and unveiled persistent seismicity features through multiple eruptions.
Piton de La Fournaise - signing of small earthquakes over time, depth and in various orientations - Doc. AGU study references sources.
Shallow earthquakes define a ring shaped structure beneath the main crater. The repetitive occurrence of events along this structure suggests it corresponds to a pre-existing zone of weakness within the edifice. We also show evidence of deep magma transfer in 2015. More than 5000 deep earthquakes define an upward migration immediately followed by the occurrence of shallow events leading to an eruption 20 days later. This suggests the creation of a hydraulic connection between the lower part of the volcanic system and a magma reservoir located near sea level. We can envisage than such replenishments of the shallow reservoir occurred in the past but were undetected because of limited deep earthquake detections.
Source: AGU - Uncovering the hidden signing of a magmatic recharge at Piton de la Fournaise volcano using small earthquakes - By O. Lengline, Z. Duputel, V. Ferrazzini