TY - JOUR

T1 - Porosity, strength, and alteration – Towards a new volcano stability assessment tool using VNIR-SWIR reflectance spectroscopy

AU - Kereszturi, Gabor

AU - Heap, Michael J.

AU - Schaefer, Lauren N.

AU - Darmawan, Herlan

AU - Deegan, Frances M.

AU - Kennedy, Ben

AU - Komorowski, Jean Christophe

AU - Mead, Stuart

AU - Rosas-Carbajal, Marina

AU - Ryan, Amy

AU - Troll, Valentin R.

AU - Villeneuve, Marlene

AU - Walter, Thomas R.

N1 - Funding Information: This research was supported by Natural Hazard Research Platform (“Too big to fail? A multidisciplinary approach to predict collapse and debris flow hazards from Mt. Ruapehu”; MAU-01-NHRP-31118 ) and partially through GK's Rutherford Discovery Fellowship (“Caught in action - volcano surveillance with hyperspectral remote sensing”; RDF-MAU2003 ). This work was supported in part by ANR grant MYGALE (“Modelling the phYsical and chemical Gradients of hydrothermal ALteration for warning systems of flank collapse at Explosive volcanoes”; ANR-21-CE49-0010 ), awarded to MJH, and by the Indonesia-German SUNDAARC agreement and represents a contribution to the programme GEOTECHNOLOGIEN by BMBF and DFG (Grant 03G0578A ). MJH also acknowledges support from the Institut Universitaire de France (IUF) and FMD and VRT acknowledge support from the Swedish Research Council and the Section for Natural Resources and Sustainable Development (NRHU) at Uppsala University . BK and GK additionally acknowledges Ministry of Business, Innovation & Employment -funded National Science Challenges – Resilience to Nature's Challenges programme (“Āhea riri ai ngā maunga puia? When will our volcanoes become angry?”; GNS-RNC047 ). Funding Information: This research was supported by Natural Hazard Research Platform (“Too big to fail? A multidisciplinary approach to predict collapse and debris flow hazards from Mt. Ruapehu”; MAU-01-NHRP-31118) and partially through GK's Rutherford Discovery Fellowship (“Caught in action - volcano surveillance with hyperspectral remote sensing”; RDF-MAU2003). This work was supported in part by ANR grant MYGALE (“Modelling the phYsical and chemical Gradients of hydrothermal ALteration for warning systems of flank collapse at Explosive volcanoes”; ANR-21-CE49-0010), awarded to MJH, and by the Indonesia-German SUNDAARC agreement and represents a contribution to the programme GEOTECHNOLOGIEN by BMBF and DFG (Grant 03G0578A). MJH also acknowledges support from the Institut Universitaire de France (IUF) and FMD and VRT acknowledge support from the Swedish Research Council and the Section for Natural Resources and Sustainable Development (NRHU) at Uppsala University. BK and GK additionally acknowledges Ministry of Business, Innovation & Employment-funded National Science Challenges – Resilience to Nature's Challenges programme (“Āhea riri ai ngā maunga puia? When will our volcanoes become angry?”; GNS-RNC047). Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Publisher Copyright: © 2022 The Author(s)

PY - 2023/1/15

Y1 - 2023/1/15

N2 - Volcano slope stability analysis is a critical component of volcanic hazard assessments and monitoring. However, traditional methods for assessing rock strength require physical samples of rock which may be difficult to obtain or characterize in bulk. Here, visible to shortwave infrared (350–2500 nm; VNIR–SWIR) reflected light spectroscopy on laboratory-tested rock samples from Ruapehu, Ohakuri, Whakaari, and Banks Peninsula (New Zealand), Merapi (Indonesia), Chaos Crags (USA), Styrian Basin (Austria) and La Soufrière de Guadeloupe (Eastern Caribbean) volcanoes was used to design a novel rapid chemometric-based method to estimate uniaxial compressive strength (UCS) and porosity. Our Partial Least Squares Regression models return moderate accuracies for both UCS and porosity, with R2 of 0.43–0.49 and Mean Absolute Percentage Error (MAPE) of 0.2–0.4. When laboratory-measured porosity is included with spectral data, UCS prediction reaches an R2 of 0.82 and MAPE of 0.11. Our models highlight that the observed changes in the UCS are coupled with subtle mineralogical changes due to hydrothermal alteration at wavelengths of 360–438, 532–597, 1405–1455, 2179–2272, 2332–2386, and 2460–2490 nm. These mineralogical changes include mineral replacement, precipitation hydrothermal alteration processes which impact the strength of volcanic rocks, such as mineral replacement, precipitation, and/or silicification. Our approach highlights that spectroscopy can provide a first order assessment of rock strength and/or porosity or be used to complement laboratory porosity-based predictive models. VNIR-SWIR spectroscopy therefore provides an accurate non-destructive way of assessing rock strength and alteration mineralogy, even from remote sensing platforms.

AB - Volcano slope stability analysis is a critical component of volcanic hazard assessments and monitoring. However, traditional methods for assessing rock strength require physical samples of rock which may be difficult to obtain or characterize in bulk. Here, visible to shortwave infrared (350–2500 nm; VNIR–SWIR) reflected light spectroscopy on laboratory-tested rock samples from Ruapehu, Ohakuri, Whakaari, and Banks Peninsula (New Zealand), Merapi (Indonesia), Chaos Crags (USA), Styrian Basin (Austria) and La Soufrière de Guadeloupe (Eastern Caribbean) volcanoes was used to design a novel rapid chemometric-based method to estimate uniaxial compressive strength (UCS) and porosity. Our Partial Least Squares Regression models return moderate accuracies for both UCS and porosity, with R2 of 0.43–0.49 and Mean Absolute Percentage Error (MAPE) of 0.2–0.4. When laboratory-measured porosity is included with spectral data, UCS prediction reaches an R2 of 0.82 and MAPE of 0.11. Our models highlight that the observed changes in the UCS are coupled with subtle mineralogical changes due to hydrothermal alteration at wavelengths of 360–438, 532–597, 1405–1455, 2179–2272, 2332–2386, and 2460–2490 nm. These mineralogical changes include mineral replacement, precipitation hydrothermal alteration processes which impact the strength of volcanic rocks, such as mineral replacement, precipitation, and/or silicification. Our approach highlights that spectroscopy can provide a first order assessment of rock strength and/or porosity or be used to complement laboratory porosity-based predictive models. VNIR-SWIR spectroscopy therefore provides an accurate non-destructive way of assessing rock strength and alteration mineralogy, even from remote sensing platforms.

KW - advanced argillic alteration

KW - debris avalanche

KW - hydrothermal alteration

KW - hyperspectral remote sensing

KW - phyllosilicates

KW - uniaxial compressive strength

UR - http://www.scopus.com/inward/record.url?scp=85143132729&partnerID=8YFLogxK

U2 - 10.1016/j.epsl.2022.117929

DO - 10.1016/j.epsl.2022.117929

M3 - Article

AN - SCOPUS:85143132729

VL - 602

JO - Earth and planetary science letters

JF - Earth and planetary science letters

SN - 0012-821X

M1 - 117929

ER -