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首页> 外文期刊>Journal of Volcanology and Geothermal Research >Radiative heat power at Stromboli volcano during 2000-2011: Twelve years of MODIS observations
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Radiative heat power at Stromboli volcano during 2000-2011: Twelve years of MODIS observations

机译：2000-2011年Stromboli火山的辐射热能：MODIS观测的十二年

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摘要

Twelve years of night-time MODIS (Moderate Resolution Imaging Spectroradiometer) observations, has been analysed to detect and quantify the radiative heat power emitted by Stromboli volcano (from March 2000 to September 2011). Using an accurate background subtraction of the MODIS signal at 4μm, we were able to discriminate two main regimes of thermal radiation, related to different levels of volcanic activity. Effusive eruptions (occurred on December 28, 2002 and February 27, 2007) radiated at an average of ～186MW with a frequency of alert detection of 50-95%. Conversely, during the typical strombolian activity, an average of～9 MW is radiated, with a frequency of alert detection of 0-45%. Although during the effusive eruptions the radiative power is basically controlled by the lava discharge rate, our results suggest that during non-effusive periods (strombolian regime) both the intensity and the frequency of MODIS alerts are controlled by the height of the magmatic column feeding the activity at the surface. In particular we found that a radiative power of ～50 MW corresponds to a high magma column which is exposed, in the vent area, at the same rate in which the deeper gas-rich magma is typically supplied within the feeding system of Stromboli (～0.3 m~3s~(-1)). In this condition the magmatic system approaches steady state regimes. Above this threshold a transition from strombolian to effusive regimes may occur as shown by the detection of ～50 MW, 8-10 days before the onset of both the last two major flank eruptions. These values were reached after 1-2 months of gradual increase of the radiative power which was likely associated the rising of the magma column within the shallowest portion of the conduit. In addition our data suggest that over the years 2000-2011 several cycles of rise and fall of the magma column have occurred, which however did not culminate into an effusive eruption but only into recurrent episodes of sustained spattering or fountaining and summit overflows. These fluctuations has substantially increased in frequency and intensity after the 2007 eruption thus suggesting that this event has perturbed in some way the shallow plumbing system of Stromboli. We stress that the detection of a radiative power higher than 50 MW is a clear evidence of a very high magma column, which may prelude the onset of an effusive eruption and/or periods of sustained vent activity. In conclusion, we suggest that systematic analysis of MODIS data can be used to detect variations in the intensity of strombolian activity and may considerably improve volcano surveillance at Stromboli, as well as at other open-system volcanoes.
机译：已对12年夜间的MODIS（中等分辨率成像光谱仪）观测进行了分析，以检测和量化Stromboli火山散发的辐射热能（从2000年3月至2011年9月）。通过精确地扣除4μm的MODIS信号的背景，我们能够区分与火山活动水平不同有关的两种主要热辐射方式。散发性喷发（分别发生于2002年12月28日和2007年2月27日）辐射平均〜186MW，警报发现的频率为50-95％。相反，在典型的节段活动期间，平均辐射〜9 MW，警报检测的频率为0-45％。尽管在爆发性喷发期间，辐射功率基本上受熔岩排放速率控制，但我们的研究结果表明，在非爆发性喷发期间（地层运动），MODIS警报的强度和频率均受馈入岩浆的岩浆柱的高度控制。表面活性。尤其是，我们发现〜50 MW的辐射功率对应于一个高的岩浆柱，该柱在通气孔区域以暴露的速率与Stromboli的进料系统内通常提供的较深的富气岩浆相同（〜 0.3 m〜3s〜（-1））。在这种情况下，岩浆系统接近稳态状态。在此阈值之上，从最后两个主要侧面爆发的开始前8-10天检测到〜50 MW可以看出，发生了从节节型向喷出状态的过渡。在辐射功率逐渐增加1-2个月后达到这些值，这很可能与管道最浅部分内的岩浆柱上升有关。此外，我们的数据表明，在2000年至2011年间，岩浆柱发生了数个上升和下降周期，但最终没有形成喷发性喷发，而只是持续的持续飞溅或喷水和山顶溢出。在2007年喷发之后，这些波动的频率和强度大大增加，因此表明该事件以某种方式扰乱了Stromboli的浅层管道系统。我们强调指出，检测到高于50 MW的辐射功率是岩浆柱非常高的明确证据，这可能会导致爆发性喷发和/或持续的喷发活动持续。总而言之，我们建议对MODIS数据进行系统分析可用于检测Strombolian活动强度的变化，并且可能会大大改善Stromboli以及其他开放系统火山的火山监测。

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