Lava effusion rates from hand-held thermal infrared imagery: an example from the June 2003 effusive activity at Stromboli

Abstract

A safe, easy and rapid method to calculate lava effusion rates using hand-held thermal image data was developed during June 2003 at Stromboli Volcano (Italy). We used a Forward Looking Infrared Radiometer (FLIR) to obtain images of the active lava flow field on a daily basis between May 31 and June 16, 2003. During this time the flow field geometry and size (where flows typically a few hundred meters long were emplaced on a steep slope) meant that near-vertical images of the whole flow field could be captured in a single image obtained from a helicopter hovering, at an altitude of 750 m and ∼1 km off shore. We used these images to adapt a thermally based effusion rate method, previously applied to low and high spatial resolution satellite data, to allow automated extraction of effusion rates from the hand-held thermal infrared imagery. A comparison between a thermally-derived (0.23-0.87 m 3 s −1 ) and dimensionally-derived effusion rate (0.56 m 3 s −1 ) showed that the thermally-derived range was centered on the expected value. Over the measurement period, the mean effusion rate was 0.38±0.25 m 3 s −1 , which Editorial responsibility: M. Carroll A. Harris ( ) · M. Patrick is similar to that obtained during the 1985-86 effusive eruption and the time-averaged supply rate calculated for normal (non-effusive) Strombolian activity. A short effusive pulse, reaching a peak of ∼1.2 m 3 s −1 , was recorded on June 3, 2003. One explanation of such a peak would be an increase in driving pressure due to an increase in the height of the magma contained in the central column. We estimate that this pulse would require the magma column to attain a height of ∼190 m above the effusive vent, which is approximately the elevation difference between the vent and the floor of the NE crater. Our approach gives an easy-to-apply method that has the potential to provide effusion rate time series with a high temporal resolution.

Satellite and Ground Based Thermal Observation of the 2014 Effusive Eruption at Stromboli Volcano

“…In addition to the atmospheric effects, the data were also corrected for emissivity. For Stromboli, a grey body assumption was applied, with a flat emissivity of 0.95 [4,5].…”

“…However, of course, the main reason is due to the higher sensitivity of the ImageIR for fresh lava radiating through the cracks in the lava crust. If the temperature data from both cameras (Figure 4) are applied to Stefan-Boltzmann's law to estimate first VRP [4,5] and then TADR, we obtain different values (Table 5). In addition, the effective temperature of the lava flow based on the dual band solution provides data for a third version of TADR.…”

“…Continuous effusive activity is uncommon for Stromboli. During the last decades, only three major effusive episodes were recorded: 1985/86 [3], 2002/03 [4,5] and 2007 [6][7][8]. The effusive activity presents no direct hazard to the island's inhabitants.…”

Lava effusion — A slow fuse for paroxysms at Stromboli volcano?

“…Using the model of Harris et al (2005), thermal imagery from both satellite-borne instruments and the helicopter-based survey were used to estimate the minimum and maximum daily effusion rates. Error budgets for the effusion rates are comparable for both the helicopter surveys and satellite imagery (± 40%, [Calvari et al, 2005a] and [Calvari et al, 2005b]).…”

Radon mapping, automatic measurements and extremely high 222Rn emissions during the 2002–2007 eruptive scenarios at Stromboli volcano

“…It can be see that radon emissions are still high at some summit stations but several others, including few stations at the northern edge of the cone and along the NE ridge of Sciara del Fuoco, show values above reference threshold values. This configuration is due to the fact that during the effusive eruption the fracture network was affected by the adjustment of the volcano edifice, and average effusion rates were still moderate (approaching 0.5 m 3 /sec according to Calvari et al, 2005;Harris et al, 2005). It is significant to recall that during January-February 2003 we measured extremely high radon activities along the fractures that were rimming the SW crater (these will be presented in a later section).…”