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Volcano dome growth, collapse and coupled processes

Periodic Reporting for period 4 - VOLCAPSE (Volcano dome growth, collapse and coupled processes )

Reporting period: 2020-03-01 to 2021-08-31

The growth and collapse of volcanoes is most dynamic at dome-building volcanoes. Volcanic eruptions at most of these volcanoes are traditionally interpreted to be triggered by deep-seated processes that operate chiefly within magma reservoirs or the conduit(s). During the VOLCAPSE consolidator project evidence is mounting that many different types of external forcing mechanisms play a significant to dominant role in triggering volcanic eruptions, especially at the dome-building volcanoes. These factors include: (a) dynamic or static stress changes caused by e.g. earthquakes, (b) topographic variations, (c) interaction with groundwater or meteorological factors, and (d) internal structure of a volcanic edifice. These factors are being evaluated in the VOLCAPSE project in great detail. The innovative element of the project is to simultaneously monitor slow and fast ground motions by combining satellite radar data with novel ground based webcam arrays placed around a volcano. Both data together allow displacement measurements on multiple temporal and spatial dimensions, covering the rates of motion expected at most dome building volcanoes.
Time-lapse camera systems were placed surrounding active target volcanoes and were also synchronized with satellite radar observations from the TerraSAR-X satellite and complemented by the European Space Agency's Copernicus program. The multi-dimensional data is allowing a view day and night, even through thick volcano eruption plumes and at high resolution. The target volcanoes initially proposed (Colima, Popocatepetl, Chaiten, Lascar, Bezymianny, Merapi) were an ideal choice, regularly visited and measurements realized in the field. Time-lapse camera systems were placed in the field, locally accessed by helicopter or drones. These cameras were also synchronized with satellite radar observations from the TerraSAR-X satellite, allowing a view day and night, even through thick volcano eruption plumes. Deformation data, changes in camera image features, and tracking of moving objects allowd the study of dome growth, its collapse and the early stages of hazardeous pyroclastic flows. An important element of the VOLCAPSE project is the training of early career scientists. Besides the large number if Bachelor, Master and PhD students working in the VOLCAPSE team, student qualification training was further supported by joint supervision and media training at the HI that allows improving communicating results to news/press and television. This became also relevant during volcanic crisis; for instance the ongoing La Palma eruption led to 122 Media Reports (print and television) following VOLCAPSE team member interviews in September / October 2021 allone. Peer review publications were numerous, with increasing impact factor journal papers towards the ending of the VOLCAPSE project. Also earliest careers are attracted, such as the PI wrote 3 children books on Volcanology with important mentioning of dome building volcanoes and modern monitoring approaches.
Within the VOLCAPSE consolidator project evidence is mounting that many different types of external forcing mechanisms play a significant to dominant role in triggering volcanic eruptions, especially at the dome-building volcanoes. These factors include: (a) dynamic or static stress changes caused by e.g. earthquakes, (b) topographic variations, (c) interaction with groundwater or meteorological factors, and (d) internal structure of a volcanic edifice. The innovative element of the project is to simultaneously monitor slow and fast ground motions by combining satellite radar data with ground based webcam arrays situated around a volcano. Both data together allow displacement measurements on multiple temporal and spatial dimensions, covering the rates of motion expected at most dome building volcanoes.
Significant progress has been made related to the technical and geoscientific tasks described in the project.
We now have a better understanding on how dome displacements affect the further magma extrusion position and rates. At our target volcanoes we could realize ideal configurations of instrument networks, and both sites have shown eruptive activity from 2015 to 2020. Results indicate that the development and directivity of domes can be better understood if the conduit stress conditions are investigated.
We studied in detail how large morphology changes in the volcano summit affect dome growth. We have studied photogrammetric data and satellite radar data and determine geomorphological changes caused by summit process. Our publications summarize that the effects at depths within the edifice are large, but then diminish rapidly at depth larger 1 km beneath the summit. Here, especially through numerical models, we could find that the topographic effects are highly significant for directing the path of magma or leading to arrest of an intrusion.
We now have a better understanding on how volcanoes are affected by extrinsic triggers such as tectonic quakes. This question was addressed by a number of our case studies and published in several articles, showing that dome growth intensifies after earthquakes, that domes may fracture following earthquakes and that this fracture follows preferred trend lines, and that some of the explosions follow heavy rainfall episodes.
We conducted detailed research on how overlapping displacement processes such as cooling (contraction), extrusion and gravity driven deformation change the overall morphometric evolution of the volcano. The complexity of displacement patterns is found to be evident and increasing with higher quality data. A case study realized at an arid volcano, Lascar in Chile, allowed generation of a large number of datasets that are not obscured by environmental limits and poor visibility. We generated over 2000 satellite radar interferograms and found that deformation processes involve cooling, thermal contraction, sagging, and gravity sliding. While it is not sure yet whether this overlapping displacement complexity can equally be found at volcanoes elsewhere, this study demonstrates that our previous picture of deforming volcano summits might have been too simplicity.
In the final stages of the project we had to be flexible. The final period of the project fell into the Covid19 pandemy, which is why a stronger focus was given to remote sensing analysis, modelling and online trainings, especially as regular field visits were not possible. We hence studied the shallow interactions between developing domes, their surface geomorphology and the basin in which the domes have formed are be investigated in great detail. Furthermore, time lapse camera systems and image analyzing software technologies developed within the course of this project are continued to be used by volcano observatories and our science partner network that developed during the VOLCAPSE project worldwide.
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