Revealing the Eruptive History of Volcanoes from Massive Cross-Correlation of Seismic Signal at Global Scale

Abstract:

We propose here a massive cross-correlation technique applied to seismic events located around volcanoes and recorded at teleseismic distance. Multichannel cross-correlations are performed between 2002 to 2012 using seismic templates occurring at the time of moderate to large volcanic eruptions. The volcanic periods are reported from the Global Volcanism Program database while the waveform data are obtained from the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). The temporal distribution of new seismic events, built from the association of teleseismic detections reveals acceleration patterns, which are highly correlated to the past eruptive activities. These newly detected events are relocated using Bayesian approach and leads to preliminary interpretation of the volcanic plumbing system. Two examples are presented. First, the large 2008 eruption (Volcanic Explosivity Index, VEI4) of Kasatochi (Aleutian Islands, 52.10°N/175.31°W) is used to demonstrate that only few seismic templates (~3) help to reveal the time scale of the eruption. Results are compared to hydroacoustic signal, which is highly correlated to the distribution of new seismic events prior and during eruption. We also show that after the peaked seismic activity (i.e., ~ 100 seismic events in 1 hour) the infrasound signal starts and signs the volcanic plume activity. The second case example reveals with success seven past volcanic eruptions of lower magnitude (VEI1 to VEI2) of the Karangetang volcano (Siau Island in Indonesia, 2.46°N/125.24°E). We show the potential of this method to detect volcanic eruptions in isolated areas. This is of special interest especially when there is no volcano observatory to monitor the volcanic activity, or when the last eruptive period is unknown.