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Breathing and Coughing: The Extraordinarily High Degassing of Popocatépetl Volcano Investigated With an SO2 Camera
摘要： How do lava domes release volcanic gases? Studying this problem is crucial to understand, and potentially anticipate, the generation of the sudden and dangerous explosive eruptions that frequently accompany dome extrusions. Since its awakening in 1994, Popocatépetl volcano has produced more than 50 lava domes and has been consistently among the strongest permanent emitters of volcanic gases. In this work, we have characterized the passive and explosive degassing between 2013 and 2016 at a high time resolution using an SO2 camera, to achieve a better understanding of the conduit processes. Our 4-year average SO2 ?ux is 45 kg/s, in line with the long-term average of the whole current eruptive period. We show that Popocatépetl volcano is essentially an open system and that passive degassing, i.e., degassing with no associated emission of lava or ash, dominates >95% of the time. This passive degassing is continuous and sustained, whether the crater contains a lava dome or not. It shows most of the time a strong periodic component, with a pseudo-period of ～5 min, and amplitudes of 30 to 60% of the average value. We could distinguish two types of explosions based on their SO2 ?ux patterns. The ?rst type (E1) occurs in the middle of the normal passive degassing and is followed by a rapid return of the SO2 ?ux down to its pre-explosive level. The second type (E2), which corresponds to the strongest events, is anticipated by a rapid decrease of the SO2 ?ux to abnormally low values and is followed by a return to its normal values. The E2 explosions are probably caused by the accumulation of gas below a rapidly compacting permeable dome. We suggest that transient episodes of gravitational compaction of the usually permeable dome and the upper conduit is the only mechanism that is fast enough to explain the sharp decrease of the SO2 ?ux that anticipates the E2 explosions. Our model is potentially applicable to a large number of andesitic volcanoes that undergo passive degassing interspersed with short-lived explosions.
关键词： volcanic degassing,Popocatépetl,lava dome,permeability,explosions,SO2 camera
更新于2025-09-23 15:22:29
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Laser-induced breakdown spectroscopy characterization of tree rings from the Popocatépetl volcano area, Mexico
摘要： Laser-induced breakdown spectroscopy (LIBS) was used to monitor macro- and micro-nutrients in pine trees exposed to two mayor activity periods of the Popocatépetl volcano in Mexico. Due to the high spatial resolution achieved with LIBS, a separate analysis of earlywood and latewood was performed. An increased concentration of potassium was found in earlywood, while calcium and sodium decreased. Besides, it was observed a similar temporal behavior for elements belonging to the same chemical group. The alkali earth metals Ca, Mg and Sr showed decreasing trends through the investigated years while alkali metals Na and K remain nearly constant. LIBS was able to detect signi?cant changes in Ca, Mg, Na and Sr intensities coincident with the 1919 Popocatépetl's eruptive period and after the volcanic activity starting at the end of 1999. Temporal evolution of the emission intensities is in agreement with the elemental composition obtained with inductively coupled plasma optical emission spectrometry.
关键词： Dendrochemistry,Laser-induced breakdown spectroscopy,Tree rings,Popocatépetl volcano
更新于2025-09-11 14:15:04