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El Chichón volcano is the most active volcano in the state of Chiapas, México, and experienced its last Plinian eruption (VEI = 5) in 1982. To better assess its volcanic hazard, we studied its readiness to erupt by estimating changes in its internal stress state. These stress changes are difficult to calculate accurately, for example in the absence of focal mechanisms, but their existence can be indirectly revealed by the presence of volcano-tectonic earthquakes, for example following a large tectonic earthquake. We show that the seismic rate recorded at El Chichón volcano increased slightly after the large Mw8.2 Tehuantepec earthquake of 8 September 2017, Chiapas. However, this rate quickly returned to its background level after only 2 months, without any external volcanic manifestations, suggesting that the volcano is not ready to erupt in the near future. Previous observations of slight increases in the volcanic seismicity rate following large earthquakes have been explained by the presence of active hydrothermal systems in the vicinity of the volcano. We propose a similar explanation for El Chichón volcano which is known for its large hydrothermal system. Furthermore, the characteristics of the 2017 seismicity (spatial and magnitude distributions), and the horizontal-to-vertical spectral ratio also confirm the presence of high amounts of water near the volcano. We show that the 2017 volcano-tectonic seismicity is of hydrothermal rather than magmatic origin, in agreement with recent independent geochemical and aeromagnetic studies. [ABSTRACT FROM AUTHOR]

Lava domes exhibit highly unpredictable and hazardous behavior, which is why imaging their morphological evolution to decipher the underlying governing mechanisms remains a major challenge. Using high-resolution satellite radar imagery enhanced with deep-learning, we image the repetitive dome construction-subsidence cycles at Popocatépetl volcano (Mexico) with very high temporal and spatial resolution. We show that these cycles resemble gas-driven rise and fall of the upper magma column, where buoyant bubble-rich magma is extruded from the conduit (in ~hours-days), and successively drained back (in ~days-months) as magma degasses and crystallizes. These cycles are superimposed on a progressive decadal crater deepening, accompanied by heat and gas flux decrease, which could be partially explained by gas depletion within the magma plumbing system. Results reinforce the idea that gas retention and escape from the magma column play a key role in the short- and long-term morphological evolution of low-viscosity lava domes and their associated hazards., (© 2023. The Author(s).)

We present a MATLAB App aimed to characterize the degree of erosion of monogenetic scoria cones from two independent sets of morphometric parameters. One quantifies the shape and size of undulations in DEM level contours through a novel parameter, the Average Erosion Index ( AEI ), using Elliptical Fourier Descriptors to calculate the wavelength spectra of undulations in selected contours over an ample range of resolutions of the database. The other is a more conventional set of parameters characterizing the vertical profiles of cones. This algorithm permits correcting those parameters for terrain inclination.•These methods aim for a consistent assessment of the erosion-related relative ages of volcanoes in extensive monogenetic fields, from DEM data.•The age-related degree of erosion is revealed by two main parameters: The Average Erosion Index ( AEI ), calculated from the Elliptic Fourier Descriptor spectrum of a scoria cone contour lines; and the aspect ratio of a scoria cone vertical profile, considering terrain inclinations, if it is assumed that all cones acquired the same morphology at the time of their formation eruptions.•The Method provides erosion metrics from a sizable range of DEM resolutions. For age-related applications, it is recommended to use resolutions better than 12 m., (© 2021 The Authors. Published by Elsevier B.V.)