# Unrest at Domuyo Volcano, Argentina, Detected by Geophysical and Geodetic Data and Morphometric Analysis

^{1}

^{2}

^{3}

^{*}

## Abstract

**:**

^{2}, from 2014 to at least March 2018, which can be explained by an inflating sill model located 7 km deep. The Bouguer anomaly reveals a negative density contrast of ~35 km wavelength, which is spatially coincident with the InSAR pattern. Our 3D density modeling suggests a body approximately 4–6 km deep with a density contrast of –550 kg/m

^{3}. Therefore, the geophysical and geodetic data allow identification of the plumbing system that is subject to inflation at these shallow crustal depths. We compared the presence and dimensions of the inferred doming area to the drainage patterns of the area, which support long-established incremental uplift according to morphometric analysis. Future studies will allow us to investigate further whether the new unrest is hydrothermal or magmatic in origin.

## 1. Introduction

## 2. Tectonic Setting and Geology of the Domuyo Volcanic Center

## 3. Materials and Methods

#### 3.1. Seismic Data

#### 3.2. InSAR Data

#### 3.3. Gravimetry Data

^{2}) throughout the results and figures.

#### 3.4. Magnetic Data

#### 3.5. Data Modeling

#### 3.5.1. Source Modeling from InSAR

^{−4}for the ascending data, resulting in 232 points, and a quadtree of 2.5 × 10

^{−4}for the descending interferogram, resulting in 82 points (see Appendix A).

^{6}iterations using posterior probability density functions to constrain the input parameters for the different geometries mentioned above.

#### 3.5.2. D Density Modeling from Bouguer Anomalies

^{3}. In the present work, we used a density contrast of –550 kg/m

^{3}to fit the gravimetric contrast of almost 20 mGal.

#### 3.6. Morphometric Analysis

## 4. Results

#### 4.1. Seismic Data

#### 4.2. InSAR Data

_{sentinel-1}= 5.54 cm).

#### 4.3. Gravimetry Mapping Results

_{1}= 26 km, was hosted in the lower crust, and was south of the Domuyo summit. The shorter anomaly had a wavelength λ

_{2}= 15 km, was shallower, and was positioned to the northeast.

#### 4.4. Magnetic Maps

#### 4.5. Source Modeling Results

#### 4.5.1. Modeling from InSAR Data

^{2}(see Appendix A), but the horizontal sill was located 0.8 km deeper than the dipping sill (6.7 km depth). To resolve which sill model better represented the deformation source, we tested both depths during modeling of gravity data, and we determined that the dipping sill better reproduced the lower anomaly. Therefore, from all of the geometries tested for the inversion, the InSAR data-set can be best explained by a rectangular sill geometry of around 7.5 × 10 km

^{2}and 0.5 m of opening with strike N58°E, and a dip orientation of 10° toward the west, according to the RMS and WRSS criteria and to the 3D density modeling.

#### 4.5.2. D Modeling from Gravity Data

^{3}) according to the predominant rhyolitic products. The differences between the modeled and the original Bouguer anomalies were minor but revealed short wavelength residuals in the southwest and in the east of the DVC (Figure 10c,d). Also, the absolute values of the residuals did not exceed 5 mGal, except for the deeper body, which differed by 10 mGal for the measured minimum anomaly value.

#### 4.6. Morphometric Results

## 5. Discussion

^{2}[13]. Understanding the details of new unrest at such volcanoes is important for generating a clearer picture of the volcanic plumbing system and for assessing potential hazards.

^{2}and 0.5 m of opening, with a strike of N58°E, with a dip of 10° to the west and a depth of 7 km from the surface.

#### Implications

## 6. Conclusions

^{2}with a 20 km diameter. The seismicity was concentrated to the southwest and was found in an area of hydrothermal activity. The area affected by deformation was also well-defined in the Bouguer gravity anomaly maps and revealed a circular-shaped, negative anomaly that was possibly associated with a reservoir at depth. We modeled the InSAR data and constructed an inflating subhorizontal sill model that may explain the observations. These geometric parameters were used to constrain the 3D density modeling that suggested a reservoir body approximately 4–6-km deep with a density contrast of –550 kg/m

^{3}, consistent with a predominantly rhyolitic magma. In a conceptual model, we compared the different data sets and models and inferred that the current unrest at the DVC is an episode of a much larger and longer-lived volcanic crustal structure located at depth. This conceptual model for Domuyo highlights the transient nature of volcanoes and/or geothermal activities of large-scale unrest episodes at volcanoes elsewhere.

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## Appendix A

**Table A1.**Inversion results for the tried geometries. R: ratio, a and b correspond to the major and minor semi-axes of the prolate spheroid; DV: volume change; DP/mu = dimensionless excess pressure (pressure change/shear modulus); Op.: opening of dislocation plane; Z: depth of one edge of rectangular source in meters (positive downwards); The coordinates X and Y have the coordinate system centered in the geographic position (−70.42° −36.62°); Strike: angle of horizontal edge with respect to North (0°/360° = N; 90° = E; 180° = S; 270° = W); Dip: angle with respect to horizontal (0° = horizontal; −90° or 90° = vertical); Width: second dimension of rectangular source, and finally Length: first dimension of rectangular source.

Model Geometry | Mogi Point Source | Rectangular Dipping Source | Penny-shaped Sill-Like Source | Prolate Spheroid Source | Horizontal Rectangular Sill |
---|---|---|---|---|---|

Ratio (km) | - | - | 1.2 | a: 2.4 with an inclination of 1.28°. b: 0.12 | - |

DV (m^{3}) | 5.107 | - | - | - | - |

DP/mu | - | - | 0.01 | 0.31 | - |

Op. (m) | - | 0.4 | - | - | 0.4 |

Z (km) | 7.9 | 6.7 | 10 | 8.7 | 7.5 |

Y (km) | 0.5 | −4.3 | 0.5 | 0.8 | −1.7 |

X (km) | 10 | 1.9 | −0.8 | −0.9 | −4.2 |

Strike (°) | - | 59 | - | 238 | 145.6 |

Dip (°) | - | -10 | - | - | - |

Width (km) | - | 10.8 | - | - | 8.2 |

Length (km) | - | 8 | - | - | 10.5 |

**Table A2.**Inversion results for the model of a rectangular dipping source. Dip: angle with respect to horizontal (0° = horizontal; −90° or 90° = vertical); Strike: angle of horizontal edge with respect to North (0°/360° = N; 90° = E; 180° = S; 270° = W); The coordinates X and Y have the coordinate system centered in the geographic position (−70.42° −36.62°); Z: depth of one edge of the rectangular source in meters (positive downwards); Opening: opening of dislocation plane.

Rectangular Dipping Source | |||||
---|---|---|---|---|---|

Model Parameters Number of iterations: 107 | Optimal | Mean | Median | 2.5% | 97.5% |

Length (km) | 8.079 | 7.772 | 7.762 | 6.141 | 9.671 |

Width (km) | 10.814 | 10.204 | 10.272 | 8.694 | 1.1492 |

Z Depth (km) | 6.673 | 6.951 | 6.946 | 5.982 | 7.958 |

Dip (°) | −9.916 | −10.517 | −10.4749 | −17.173 | −3.984 |

Strike (°) | 58.609 | 55.5027 | 56.0426 | 27.280 | 84.179 |

X (km) | 1.970 | 2.046 | 2.116 | −0.323 | 3.798 |

Y (km) | −4.287 | −3.830 | −3.972 | −4.967 | −1.969 |

**Figure A1.**Posterior probability density functions of the model parameters of a rectangular dipping source. The red line indicates the maximum a posteriori probability solution. See the description of Table 2. for parameters details.

**Figure A2.**Subsampled used for the InSAR modeling. (

**a**) Ascending subsampled (quadtree = 2 × 10

^{−4}); (

**b**) descending subsampled data (quadtree = 2.5 × 10

^{−4}).

## Appendix B

**Figure A3.**Seismic data. (

**a**) Latitude and longitude uncertainties of the seismic events. (

**b**) Depth vs. longitude positions. The red line indicates the threshold used for this work. (

**c**) Cumulative chart of seismic events per month.

## Appendix C

**Figure A4.**(

**a**) Magnetic anomaly in the Domuyo Volcanic Center (DVC) and the surrounding area, delineated by contour lines. Note a semicircular anomaly with values above 70 nT placed over the summit of the DVC which is interpreted as associated with the silicic magmatism represented by the central dome. (

**b**) Geologic map of the Domuyo Volcanic Center (DVC) and black contour lines that delineate magnetic anomalies with values above 0 nT. Note peripheral-to-the-central dome positive magnetic anomalies interpreted as magmatic material intruding the Mesozoic rocks at depth, potentially connected with the rims of a collapsed calder.

## Appendix D

**Figure A5.**Geologic map of the Domuyo Volcanic Center (DVC). The topographic swath profiles 5–8 correspond to numbered rivers marked in white in the map. The rivers 1–4 are located where the magmatic products cover the area homogeneously and no major compositional changes exist.

## References

- Coleman, D.; Gray, W.; Geology, A.G. Rethinking the Emplacement and Evolution of Zoned Plutons: Geochronologic Evidence for Incremental Assembly of the Tuolumne Intrusive Suite, California. Geology
**2004**, 32, 433–436. [Google Scholar] [CrossRef] - Annen, C. From Plutons to Magma Chambers: Thermal Constraints on the Accumulation of Eruptible Silicic Magma in the Upper Crust. Earth Planet. Sci. Lett.
**2009**, 284, 409–416. [Google Scholar] [CrossRef] - Schöpa, A.; Annen, C. The Effects of Magma Flux Variations on the Formation and Lifetime of Large Silicic Magma Chambers. J. Geophys. Res. Solid Earth
**2013**, 118, 926–942. [Google Scholar] [CrossRef] - Sparks, R.S.J.; Annen, C.; Blundy, J.D.; Cashman, K.V.; Rust, A.C.; Jackson, M.D. Formation and dynamics of magma reservoirs. Philos. Trans. R. Soc. A Math. Phys. Eng. Sci.
**2019**, 377, 20180019. [Google Scholar] [CrossRef] [PubMed] [Green Version] - Morgan, S.; Horsman, E.; Tikoff, B.; de Saint-Blanquat, M.; Habert, G. Sheet-like emplacement of satellite laccoliths, sills and bysmaliths of the Henry Mountains, southern Utah. In Interior Western United States Field Guide 6; Pederson, J., Dehler, C.M., Eds.; The Geological Society of America: Boulder, CO, USA, 2005; pp. 283–309. [Google Scholar]
- Menand, T. Physical Controls and Depth of Emplacement of Igneous Bodies: A Review. Tectonophysics
**2011**, 500, 11–19. [Google Scholar] [CrossRef] - Edmonds, M.; Cashman, K.V.; Holness, M.; Jackson, M. Architecture and dynamics of magma reservoirs. Philos. Trans. R. Soc. A Math. Phys. Eng. Sci.
**2019**, 377. [Google Scholar] [CrossRef] [PubMed] - Bachmann, O.; Miller, C.F.; De Silva, S.L. The volcanic–plutonic connection as a stage for understanding crustal magmatism. J. Volcanol. Geotherm. Res.
**2007**, 167, 1–23. [Google Scholar] [CrossRef] - Smith, R.L. Ash-Flow Magmatism. Geol. Soc. Am. Spec. Pap.
**1979**, 180, 5–27. [Google Scholar] - Jellinek, A.M.; DePaolo, D.J. A Model for the Origin of Large Silicic Magma Chambers: Precursors of Caldera-Forming Eruptions. Bull. Volcanol.
**2003**, 65, 363–381. [Google Scholar] [CrossRef] - Pritchard, M.E.; De Silva, S.L.; Michelfelder, G.; Zandt, G.; Mcnutt, S.R.; Gottsmann, J.; West, M.E.; Blundy, J.; Christensen, D.H.; Finnegan, N.J. Synthesis: PLUTONS: Investigating the Relationship between Pluton Growth and Volcanism in the Central Andes. Geosphere
**2018**, 14, 954–982. [Google Scholar] [CrossRef] - De Silva, S. Arc magmatism, calderas, and supervolcanoes. Geology
**2008**, 36, 671–672. [Google Scholar] [CrossRef] - Ruch, J.; Anderssohn, J.; Walter, T.; Motagh, M. Caldera-Scale Inflation of the Lazufre Volcanic Area, South America: Evidence from InSAR. J. Volcanol. Geotherm. Res.
**2008**, 174, 337–344. [Google Scholar] [CrossRef] - Fialko, Y.A.; Pearse, J. Sombrero uplift above the Altiplano-Puna magma body: Evidence of a ballooning mid-crustal diapir. Science
**2012**, 338, 250–252. [Google Scholar] [CrossRef] [PubMed] - Singer, B.S.; Andersen, N.L.; Le Mével, H.; Feigl, K.L.; DeMets, C.; Tikoff, B.; Thurber, C.H.; Jicha, B.R.; Cardona, C.; Córdova, L.; et al. Dynamics of a Large, Restless, Rhyolitic Magma System at Laguna Del Maule, Southern Andes, Chile. GSA Today
**2014**, 24, 4–10. [Google Scholar] [CrossRef] - Pritchard, M.E.; Simons, M. An InSAR-Based Survey of Volcanic Deformation in the Central Andes. Geochem. Geophys. Geosystems
**2004**, 5. [Google Scholar] [CrossRef] - Froger, J.-L.; Remy, D.; Bonvalot, S.; Legrand, D. Two Scales of Inflation at Lastarria-Cordon Del Azufre Volcanic Complex, Central Andes, Revealed from ASAR-ENVISAT Interferometric Data. Earth Planet. Sci. Lett.
**2007**, 255, 148–163. [Google Scholar] [CrossRef] - Chiodini, G.; Liccioli, C.; Vaselli, O.; Calabrese, S.; Tassi, F.; Caliro, S.; Caselli, A.; Agusto, M.; D’Alessandro, W. The Domuyo Volcanic System: An Enormous Geothermal Resource in Argentine Patagonia. J. Volcanol. Geotherm. Res.
**2014**, 274, 71–77. [Google Scholar] [CrossRef] - VOGRIPA. SI_VNUM 357067. Available online: http://www.bgs.ac.uk/vogripa/searchVOGRIPA.cfc?method=detail&id=2209 (accessed on 16 September 2019).
- Galetto, A.; García, V.; Caselli, A. Structural Controls of the Domuyo Geothermal Field, Southern Andes (36°38′S), Argentina. J. Struct. Geol.
**2018**, 114, 76–94. [Google Scholar] [CrossRef] - Hildreth, W.E.S.; Grunder, A.L.; Drake, R.E. The Loma Seca Tuff and the Calabozos Caldera: A Major Ash-Flow and Caldera Complex in the Southern Andes of Central Chile. Geol. Soc. Am. Bull.
**1984**, 95, 45–54. [Google Scholar] [CrossRef] - Hildreth, W.; Fierstein, J.; Godoy, E.; Drake, R.E.; Singer, B. The Puelche Volcanic Field: Extensive Pleistocene Rhyolite Lava Flows in the Andes of Central Chile. Rev. Geol. Chile
**1999**, 26, 275–309. [Google Scholar] [CrossRef] - Hildreth, W. Laguna Del Maule Volcanic Field: Eruptive History of a Quaternary Basalt-to-Rhyolite Distributed Volcanic Field on the Andean Rangecrest in Central Chile; Servicio Nacional de Geología y Minería-Chile: Providencia, Chile, 2010. [Google Scholar]
- Llambías, E.J.; Leanza, H.A.; Galland, O.; Arregui, C.; Carbone, O.; Danieli, J.C.; Vallés, J.M. Agrupamiento Volcánico Tromen-Tilhue. In Geología y Recursos Naturales de la Provincia de Neuquén: XVIII Congreso Geológico Argentino; Asociación Geológica Argentina: Neuquén, Argentina, 2011; pp. 627–636. [Google Scholar]
- Folguera, A.; Zapata, T.; Ramos, V.A. Late Cenozoic Extension and the Evolution of the Neuquén Andes. Evol. an Andean Margin a Tecton. Magmat. View from Andes to Neuquén Basin (35°–39°S lat). Geol. Soc. Am. Spec. Pap.
**2006**, 407, 267–285. [Google Scholar] [CrossRef] - Søager, N.; Holm, P.M.; Llambías, E.J. Payenia Volcanic Province, Southern Mendoza, Argentina: OIB Mantle Upwelling in a Backarc Environment. Chem. Geol.
**2013**, 349, 36–53. [Google Scholar] [CrossRef] - Pesicek, J.D.; Engdahl, E.R.; Thurber, C.H.; Deshon, H.R.; Lange, D. Mantle Subducting Slab Structure in the Region of the 2010 M8.8 Maule Earthquake (30–40°S), Chile. Geophys. J. Int.
**2012**, 191, 317–324. [Google Scholar] [CrossRef] - Rojas Vera, E.A.; Folguera, A.; Zamora Valcarce, G.; Bottesi, G.; Ramos, V.A. Structure and Development of the Andean System between 36° and 39°S. J. Geodyn.
**2014**, 73, 34–52. [Google Scholar] [CrossRef] - Burd, A.I.; Booker, J.R.; Mackie, R.; Favetto, A.; Pomposiello, M.C. Three-Dimensional Electrical Conductivity in the Mantle beneath the Payun Matru Volcanic Field in the Andean Backarc of Argentina. Geophys. J. Int.
**2014**, 198, 812–827. [Google Scholar] [CrossRef] - Astort, A.; Colavitto, B.; Sagripanti, L.; García, H.; Echaurren, A.; Soler, S.; Ruíz, F.; Folguera, A. Crustal and Mantle Structure Beneath the Southern Payenia Volcanic Province Using Gravity and Magnetic Data. Tectonics
**2019**, 38, 144–158. [Google Scholar] [CrossRef] - Brousse, R.; Pesce, A.H. Cerro Domo: Un volcán Cuartario con posibilidades geotermicas. Provincia del Neuquén. In Proceedings at the 5th Congreso Latinoamericano de Geología: Buenos Aires; Servicio Geológico Nacional, Subsecretaria de Minería: Buenos Aires, Argentina, 1982; Volume 4, pp. 197–208. [Google Scholar]
- Japan International Cooperation Agency (JICA). Interim Report on the Northern Neuquén Geothermal Development Project, Argentine Republic; Japan International Cooperation Agency: Tokyo, Japan, 1983. [Google Scholar]
- Miranda, F.J. Caracterización Petrográfica y Geoquímica Del Cerro Domuyo. Pcia. de Neuquén, Argentina. Bachelor’s Thesis, Universidad de Buenos Aires, Buenos Aires, Argentina, 1996. [Google Scholar]
- Miranda, F.; Folguera, A.; Leal, P.; Naranjo, J.; Pesce, A. Upper Pliocene to Lower Pleistocene Volcanic Complexes and Upper Neogene Deformation in the South-Central Andes (36°30’–38°S). Geol. Soc. Am. Spec. Pap.
**2006**, 407, 287–298. [Google Scholar] [CrossRef] - Pesce, A. The Domuyo Geothermal Area, Neuquén, Argentina. GRC Trans.
**2010**, 37, 309–314. [Google Scholar] - Llambías, E.J.; Palacios, M.; Danderfer, J.C.; Brogioni, N. Las Rocas Ígneas Cenozoicas Del Volcán Domuyo y Áreas Adyacentes, Provincia Del Neuquén. In 7th Congreso Geológico Argentino; Asociación Geológica Argentina: Neuquén, Argentina, 1978; pp. 569–584. [Google Scholar]
- Japan International Cooperation Agency (JICA). Final Report on the Northern Neuquen Geothermal Development Project, Argentine Republic; Third Phase Survey, No 25; Japan International Cooperation Agency: Tokyo, Japan, 1984. [Google Scholar]
- Folguera, A.; Introcaso, A.; Giménez, M.; Ruiz, F.; Martinez, P.; Tunstall, C.; García Morabito, E.; Ramos, V.A. Crustal Attenuation in the Southern Andean Retroarc (38°–39°30′S) Determined from Tectonic and Gravimetric Studies: The Lonco-Luán Asthenospheric Anomaly. Tectonophysics
**2007**, 439, 129–147. [Google Scholar] [CrossRef] - Pesce, A. Evaluación Geotérmica Del Area Cerro Domuyo, Provincia Del Neuquén. República Argentina. Rev. Bras. Geofísica
**1987**, 5, 283–299. [Google Scholar] - Sparks, R.S.J.; Biggs, J.; Neuberg, J.W. Monitoring volcanoes. Science
**2012**, 335, 1310–1311. [Google Scholar] [CrossRef] [PubMed] - White, R.; McCausland, W. Volcano-Tectonic Earthquakes: A New Tool for Estimating Intrusive Volumes and Forecasting Eruptions. J. Volcanol. Geotherm. Res.
**2016**, 309, 139–155. [Google Scholar] [CrossRef] - Dzurisin, D. Volcano Deformation: Geodetic Monitoring Techniques; Blondel, P., Ed.; Spriger-Praxis Books in Geophysical Sciences: Berlin/Heildelberg, Germany, 2006. [Google Scholar]
- Lockwood, J.P.; Harzlett, R.W. Volcanoes: Global Prespectives; John Wiley & Sons: Hoboken, NJ, USA, 2010. [Google Scholar]
- Havskov, J.; Ottemoller, L. SEISAN: The Earthquake Software, 2001.
- Lienert, B.; Berg, E.; Ln, F. HYPOCENTER: An Earthquake Location Method Using Centered, Scaled, and Adaptively Damped Least Squares. Bull. Seism. Soc. Am.
**1986**, 76, 771–783. [Google Scholar] - Lienert, B.R.; Havskov, J. A Computer Program for Locating Earthquakes both Locally and Globally. Seismol. Res. Lett.
**1995**, 66, 26–36. [Google Scholar] [CrossRef] - Correa-Otto, S.; Nacif, S.; Pesce, A.; Nacif, A.; Gianni, G.; Furlani, R.; Giménez, M.; Francisco, R. Intraplate Seismicity Recorded by a Local Network in the Neuquén Basin, Argentina. J. S. Am. Earth Sci.
**2018**, 87, 211–220. [Google Scholar] [CrossRef] - Valade, S.; Ley, A.; Massimetti, F.; D’Hondt, O.; Laiolo, M.; Coppola, D.; Loibl, D.; Walter, T.R. Towards Global Volcano Monitoring Using Multisensor Sentinel Missions and Artificial Intelligence: The MOUNTS Monitoring System. Remote Sens.
**2019**, 11, 1528. [Google Scholar] [CrossRef] - Pinel, V.; Poland, M.P.; Hooper, A. Volcanology: Lessons Learned from Synthetic Aperture Radar Imagery. J. Volcanol. Geotherm. Res.
**2014**, 289, 81–113. [Google Scholar] [CrossRef] - Feigl, K.L.; Le Mével, H.; Tabrez Ali, S.; Córdova, L.; Andersen, N.L.; DeMets, C.; Singer, B.S. Rapid uplift in Laguna del Maule volcanic field of the Andean Southern Volcanic zone (Chile) 2007–2012. Geophys. J. Int.
**2013**, 196, 885–901. [Google Scholar] [CrossRef] - Arnold, D.W.D.; Biggs, J.; Wadge, G.; Mothes, P. Using satellite radar amplitude imaging for monitoring syn-eruptive changes in surface morphology at an ice-capped stratovolcano. Remote Sens. Environ.
**2018**, 209, 480–488. [Google Scholar] [CrossRef] [Green Version] - Goldstein, R.M.; Werner, C.L. Radar Interferogram Filtering for Geophysical Applications. Geophys. Res.
**1998**, 25, 4035–4038. [Google Scholar] [CrossRef] - Chen, C.W.; Zebker, H.A. Network Approaches to Two-Dimensional Phase Unwrapping: Intractability and Two New Algorithms. JOSA A
**2000**, 17, 401–414. [Google Scholar] [CrossRef] - Chen, C.W.; Zebker, H.A. Two-Dimensional Phase Unwrapping with Use of Statistical Models for Cost Functions in Nonlinear Optimization. JOSA A
**2001**, 18, 338–351. [Google Scholar] [CrossRef] [PubMed] - Chen, C.W.; Zebker, H.A. Phase Unwrapping for Large SAR Interferograms: Statistical Segmentation and Generalized Network Models. IEEE Trans. Geosci. Remote Sens.
**2002**, 40, 1709–1719. [Google Scholar] [CrossRef] - Lundgren, P.; Girona, T.; Samsonov, S.; Realmuto, V.; Liang, C. Under the radar: New Activity beneath the “Roof of Patagonia” Domuyo volcano, Argentina. In Proceedings of the 19th General Assembly of WEGENER, Grenoble, France, 10–13 September 2018. [Google Scholar]
- Peltzer, G.; Crampé, F.; Rosen, P. The Mw 7.1, Hector Mine, California earthquake: Surface rupture, surface displacement field, and fault slip solution from ERS SAR data. Comptes Rendus L'académie Sci. Ser. IIA-Earth Planet. Sci.
**2001**, 333, 545–555. [Google Scholar] [CrossRef] - Wright, T.; Parsons, B.; Fielding, E. Measurement of interseismic strain accumulation across the North Anatolian Fault by satellite radar interferometry. Geophys. Res. Lett.
**2001**, 28, 2117–2120. [Google Scholar] [CrossRef] - Wright, T.J.; Parsons, B.E.; Lu, Z. Toward mapping surface deformation in three dimensions using InSAR. Geophys. Res. Lett.
**2004**, 31. [Google Scholar] [CrossRef] - Fialko, Y. Interseismic strain accumulation and the earthquake potential on the southern San Andreas fault system. Nature
**2006**, 441, 968. [Google Scholar] [CrossRef] - Biggs, J. InSAR Observations of the Earthquake Cycle on the Denali Fault, Alaska. Ph.D. Thesis, University of Oxford, Oxford, UK, 2007. [Google Scholar]
- Jo, M.J.; Jung, H.S.; Won, J.S. Detecting the source location of recent summit inflation via three-dimensional InSAR observation of Kīlauea volcano. Remote Sens.
**2015**, 7, 14386–14402. [Google Scholar] [CrossRef] - Deplus, C.; Bonvalot, S.; Dahrin, D.; Diament, M.; Harjono, H.; Dubois, J. Inner Structure of the Krakatau Volcanic Complex (Indonesia) from Gravity and Bathymetry Data. J. Volcanol. Geotherm. Res.
**1995**, 64, 23–52. [Google Scholar] [CrossRef] - Furuya, M.; Okubo, S.; Sun, W.; Tanaka, Y.; Oikawa, J.; Watanabe, H.; Maekawa, T. Spatiotemporal Gravity Changes at Miyakejima Volcano, Japan: Caldera Collapse, Explosive Eruptions and Magma Movement. J. Geophys. Res
**2003**, 108, 2219. [Google Scholar] [CrossRef] - Miller, C.A.; Williams-Jones, G.; Fournier, D.; Witter, J. 3D Gravity Inversion and Thermodynamic Modelling Reveal Properties of Shallow Silicic Magma Reservoir beneath Laguna Del Maule, Chile. Earth Planet. Sci. Lett.
**2017**, 459, 14–27. [Google Scholar] [CrossRef] - Gotze, H.J.; Kirchner, A. Interpretation of gravity and geoid in the Central Andes between 20 degrees and 29 degrees S. J. S. Am. Earth Sci.
**1997**, 10, 179–188. [Google Scholar] [CrossRef] - Potro, R.; Díez, M.; Blundy, J.; Camacho, A.G.; Gottsmann, J. Diapiric ascent of silicic magma beneath the Bolivian Altiplano. Geophys. Res. Lett.
**2013**, 40, 2044–2048. [Google Scholar] [CrossRef] [Green Version] - Blakely, R.J. Potential Theory in Gravity and Magnetic Applications; Cambridge University Press: Cambridge, UK, 1996. [Google Scholar]
- LaFehr, T.R. Standardization in Gravity Reduction. Geophysics
**1991**, 56, 1170–1178. [Google Scholar] [CrossRef] - Nagy, D. The Gravitational Attraction of a Right Rectangular Prism. Geophysics
**1966**, 31, 362–371. [Google Scholar] [CrossRef] - Johnston, M.J.S. Review of electric and magnetic fields accompanying seismic and volcanic activity. Surv. Geophys.
**1997**, 18, 441–475. [Google Scholar] [CrossRef] - Li, X. Understanding 3D Analytic Signal Amplitude. Geophysics
**2006**, 71, L13–L16. [Google Scholar] [CrossRef] - Miller, C.A.; Williams-Jones, G. Internal Structure and Volcanic Hazard Potential of Mt Tongariro, New Zealand, from 3D Gravity and Magnetic Models. J. Volcanol. Geotherm. Res.
**2016**, 319, 12–28. [Google Scholar] [CrossRef] - Paoletti, V.; Passaro, S.; Fedi, M.; Marino, C.; Tamburrino, S.; Ventura, G. Subcircular Conduits and Dikes Offshore the Somma-Vesuvius Volcano Revealed by Magnetic and Seismic Data. Geophys. Res. Lett.
**2017**, 43, 9544–9551. [Google Scholar] [CrossRef] - Bagnardi, M.; Hooper, A. Inversion of Surface Deformation Data for Rapid Estimates of Source Parameters and Uncertainties: A Bayesian Approach. Geochem. Geophys. Geosyst.
**2018**, 19, 2194–2211. [Google Scholar] [CrossRef] - Okada, Y. Surface deformation due to shear and tensile faults in a half-space. Bull. Seismol. Soc. Am.
**1985**, 75, 1135–1154. [Google Scholar] - Yang, X.; Davis, P.M.; Dieterich, J.H. Deforlnation from Inflation of a Dipping Finite Prolate Spheroid in an Elastic Half-Space as a Model for Volcanic Stressing. J. Geophys. Res. Solid Earth
**1988**, 93, 4249–4257. [Google Scholar] [CrossRef] - Fialko, Y.; Khazan, Y.; Simons, M. Deformation due to a pressurized horizontal circular crack in an elastic half-space, with applications to volcano geodesy. Geophys. J. Int.
**2001**, 146, 181–190. [Google Scholar] [CrossRef] [Green Version] - Mogi, K. Relations between the eruptions of various volcanoes and the deformations of the ground surfaces around them. Earthq. Res. Inst.
**1958**, 36, 99–134. [Google Scholar] - Akaike, H. On the statistical estimation of the frequency response function of a system having multiple input. Ann. Inst. Stat. Math.
**1965**, 17, 185–210. [Google Scholar] [CrossRef] - Pepe, S.; D’Auria, L.; Castaldo, R.; Casu, F.; De Luca, C.; De Novellis, V.; Sansosti, E.; Solaro, G.; Tizzani, P. The Use of Massive Deformation Datasets for the Analysis of Spatial and Temporal Evolution of Mauna Loa Volcano (Hawai’i). Remote Sens.
**2018**, 10, 968. [Google Scholar] [CrossRef] - Pepe, S.; Castaldo, R.; De Novellis, V.; D’Auria, L.; De Luca, C.; Casu, F.; Sansosti, E.; Tizzani, P. New insights on the 2012–2013 uplift episode at Fernandina Volcano (Galapagos). Geophys. J. Int.
**2017**, 211, 637–685. [Google Scholar] [CrossRef] - Götze, H.J. Über Den Einsatz Interaktiver Computergraphik Im Rahmen 3-Dimensionaler Interpretationstechniken in Gravimetrie Und Magnetik. Ph.D. Thesis, Technische Universität Clausthal, Clausthal-Zellerfeld, Germany, 1984. [Google Scholar]
- Götze, H.J. Potential Methods and Geoinformation Systems. In Handbook of Geomathematics; Springer: Berlin, Germany, 2014. [Google Scholar]
- Götze, H.-J.; Lahmeyer, B. Application of Three-dimensional Interactive Modeling in Gravity and Magnetics. Geophysics
**1988**, 53, 1096–1108. [Google Scholar] [CrossRef] - Schmidt, S.; Götze, H.-J. Interactive Visualization and Modification of 3D-Models Using GIS-Functions. Phys. Chem. Earth
**1998**, 23, 289–295. [Google Scholar] [CrossRef] - Breunig, M.; Cremers, A.B.; Götze, H.J.; Schmidt, S.; Seidemann, R.; Shumilov, S.; Siehl, A. Geological Mapping Based on 3D Models Using an Interoperable GIS. GIS-Heidelberg
**2000**, 13, 12–18. [Google Scholar] - Schmidt, S.; Plonka, C.; Götze, H.-J.; Lahmeyer, B. Hybrid Modelling of Gravity, Gravity Gradients and Magnetic Fields. Geophys. Prospect.
**2011**, 59, 1046–1051. [Google Scholar] [CrossRef] - Alvers, M.R.; Götze, H.J.; Barrio-Alvers, L.; Schmidt, S.; Lahmeyer, B.; Plonka, C. A novel warped-space concept for interactive 3D-geometry-inversion to improve seismic imaging. First Break
**2014**, 32, 4. [Google Scholar] - Alvers, M.R.; Barrio-Alvers, L.; Bodor, C.; Gotze, H.J.; Lahrneyer, B.; Plonka, C.; Schmidt, S. Quo vadis inversión? First Break
**2015**, 33, 65–74. [Google Scholar] - Götze, H.J.; Schmidt, S.; Menzel, P. Integrative Interpretation of Potential Field Data by 3D-Modeling and Visualization. Oil Gas Eur. Mag.
**2017**, 43, 202–208. [Google Scholar] - Keller, E.A.; Gurrola, L.; Tierney, T.E. Geomorphic Criteria to Determine Direction of Lateral Propagation of Reverse Faulting and Folding. Geology
**1999**, 27, 515–518. [Google Scholar] [CrossRef] - Pazzaglia, F.J.; Gardner, T.W.; Merritts, D.J. Bedrock Fluvial Incision and Longitudinal Profile Development over Geologic Time Scales Determined by Fluvial Terraces. In Rivers Over Rock: Fluvial Processes in Bedrock Channels; Geophysical Monograph Series; American Geophysical Union: Washington, DC, USA, 1998; Volume 107, pp. 207–235. 107p. [Google Scholar]
- Wobus, C.; Whipple, K.X.; Kirby, E.; Snyder, N.; Johnson, J.; Spyropolou, K.; Crosby, B.; Sheehan, D. Tectonics from Topography: Procedures, Promise, and Pitfalls. Tecton. Clim. Landsc. Evol. Geol. Soc. Am. Spec. Pap.
**2006**, 398, 55–74. [Google Scholar] [CrossRef] - Kirby, E.; Whipple, K.X. Expression of Active Tectonics in Erosional Landscapes. J. Struct. Geol.
**2012**, 44, 54–75. [Google Scholar] [CrossRef] - Molin, P.; Fubelli, G.; Nocentini, M.; Sperini, S.; Ignat, P.; Grecu, F.; Dramis, F. Interaction of Mantle Dynamics, Crustal Tectonics, and Surface Processes in the Topography of the Romanian Carpathians: A Geomorphological Approach. Glob. Planet. Chang.
**2012**, 90–91, 58–72. [Google Scholar] [CrossRef] - Sagripanti, L.; Rojas Vera, E.A.; Gianni, G.M.; Folguera, A.; Harvey, J.E.; Farías, M.; Ramos, V.A. Neotectonic Reactivation of the Western Section of the Malargüe Fold and Thrust Belt (Tromen Volcanic Plateau, Southern Central Andes). Geomorphology
**2015**, 232, 164–181. [Google Scholar] [CrossRef] - Schwanghart, W.; Kuhn, N.J. TopoToolbox: A Set of Matlab Functions for Topographic Analysis. Environ. Model. Softw.
**2010**, 25, 770–781. [Google Scholar] [CrossRef] - Schwanghart, W.; Scherler, D. Short Communication: TopoToolbox MATLAB Based Software for Topographic Analysis and Modeling in Earth Surface Sciences. Earth Surf. Dyn.
**2014**, 2, 1–7. [Google Scholar] [CrossRef] - Hooper, A.; Zebker, H.; Segall, P.; Kampes, B. A new method for measuring deformation on volcanoes and other natural terrains using InSAR persistent scatterers. Geophys. Res. Lett.
**2004**, 31. [Google Scholar] [CrossRef] - Crosetto, M.; Monserrat, O.; Cuevas-González, M.; Devanthéry, N.; Crippa, B. Persistent scatterer interferometry: A review. ISPRS J. Photogramm. Remote Sens.
**2016**, 115, 78–89. [Google Scholar] [CrossRef] - Walter, T.R.; Motagh, M. Deflation and Inflation of a Large Magma Body beneath Uturuncu Volcano, Bolivia? Insights from InSAR Data, Surface Lineaments and Stress Modelling. Geophys. J. Int.
**2014**, 198, 462–473. [Google Scholar] [CrossRef]

**Figure 1.**Location of the Domuyo Volcanic Center (DVC) in the Andean Southern Volcanic Zone.

**(a)**The DVC belongs to a belt of bimodal activity that is located between the arc front and the Payenia flood basalts shown in gray (see text for further details). Blue triangles indicate seismic stations, and dashed black lines delimit the Loncopue (LT) and Las Loicas troughs (LLT), two extensional depocenters that formed in the last 5 My. (

**b**) A zoomed-in view of the study area with principal mountain peaks and the Plio-Pleistocene volcanic centers (light red shade) surrounding the DVC. Red circles indicate known sites of thermal activity [18], concentrated on the west side of the DVC, and the small, inverted black triangles represent the gravity and magnetic measurement network that was used in this work. Measurements were made approximately every 1000 m. (

**c**) The inset figure shows South America, and the red triangles indicate, from north to south, the locations of the Uturuncu, Lazufre, Laguna del Maule, and Domuyo volcanoes that represent the selected and recently detected large-scale inflation sites.

**Figure 2.**Differential interferometric synthetic aperture radar (d-InSAR) maps allow relating the number of fringes (y axis) versus the temporal baseline (x axis). From the 27 data pairs, we deduced a linear trend of ~12 cm/year for the DVC deformation.

**Figure 3.**Yellow dots and squares indicate the measured seismic events over the DVC area (yellow squares represent a group of seismic events located over the summit of the DVC). The black dashed lines correspond to identified neotectonic extensional faults [20]. Red dots indicate associated thermal activity.

**Figure 4.**Sentinel-1 Interferograms. (

**a**) Ascending 5 May 2017 to 1 March 2018. (

**b**) Descending 10 May 2017 to 30 March 2018. An uplift in the LOS direction towards the satellite for both products indicates an uplift of 14 cm (λ

_{sentinel-1}= 5.54).

**Figure 5.**Deformation velocities (unwrapped interferograms/time span, in cm/year) used to create a stack. The images with labels (

**a1**–

**a6**) and (

**b1**–

**b6**) correspond to six products each, in ascending and descending configurations, respectively (see Table 1). Each product has been normalized to a one-year period for the stacking process; see Table 1 for more details. Images (

**a7**) and (

**b7)**correspond to the mean velocities for each satellite configuration; on average, the deformation velocity was 11 cm/year for the ascending products (

**a7**) and 13 cm/year for the descending products (

**b7**).

**Figure 6.**Bouguer anomaly map from terrestrial data. (

**a**) Bouguer anomaly without filtering, (

**b**) regional Bouguer anomaly from an upward continuation of 20 km, and (

**c**) residual Bouguer anomaly map calculated by removing the fitted data (shown in panel

**b**) from the original data (shown in panel

**a**) calculated at 20 km depth. The wavelengths λ

_{1}and λ

_{2}indicate the two principal negative anomalies. These can be interpreted as the expressions of fluid-bearing reservoirs at depth. Red dots correspond to thermal activity. The black dashed line corresponds to the deformed area identified from the InSAR data, and the black triangles show the main mountain peaks.

**Figure 7.**Magnetic anomalies in nT, (

**a**) total magnetic anomaly, (

**b**) reduced-to-the pole anomalies, and (

**c**) analytic signal. The black dashed circle indicates the deformed area as shown by InSAR products, red dots represent the areas of hydrothermal activity, black triangles correspond to the main mountain peaks, and the black dashed lines delineate the principal neotectonic extensional structures over the area.

**Figure 9.**Images (

**a**) and (

**d**) correspond to the ascending and descending Sentinel-1 interferogram products, respectively, for the May 2017 to March 2018 period. Images (

**b**) and (

**e**) correspond to the modeling results from GBIS software, using a rectangular dipping source [76]. Images (

**c**) and (

**f**) are the corresponding residuals.

**Figure 10.**3D density-modeled Bouguer anomalies from the two tested geometries: (

**a**) the modeled body located at 4 km depth. (

**b**) The geometry adjusted to the InSAR modeling that is located at 6 km depth. (

**c**) The corresponding residuals from (

**a**). (

**d**) The corresponding residuals from (

**b**) that present higher values at the center of the anomaly.

**Figure 11.**Source deformation models. From top to bottom: (

**a**) The deformation pattern from InSAR data superimposed on a digital elevation model of the DVC, below a rectangular dipping sill at 7 km depth from the surface with dimensions of 7.5 × 10 km

^{2}and a 0.5 m opening, with a dipping orientation of 10° toward northwest and a northeast–southwest strike of N58°E, obtained from GBIS modeling of the InSAR data. (

**b**) Modeled Bouguer anomaly map (IGMAS +) from a 3D density model with a geometry of similar dimensions as (

**a**) but was slightly longer and only at 4 km depth from the surface. Finally, (

**c**) modeled Bouguer anomaly map (IGMAS +) following the dimensions of the GBIS modeling, with a mean depth of 7 km from the surface.

**Figure 12.**Digital elevation model of the DVC showing the deformation pattern from the InSAR data and the fluvial network with the watershed boundaries shown as gray lines (1–8). Topographic swath profiles 1–4 of the main trunks of the basins draining the western slope of the DVC are marked in white on the map. Red stars over the swath profiles represent changes in the topography of the trunk valleys, indicating changes in relief that nucleate through the first two fringes derived from the InSAR products (the abscissa axis of the swath profiles starts downstream and goes up to the headwaters).

**Table 1.**Details of the Sentinel-1 datasets used in the stacking process corresponding to Single Look Complex (SLC) product types with Interferometric Wide (IW) beam mode. B

_{⊥}refers to the perpendicular baseline. Bt refers to the time baseline between data sets. The code refers to the interferograms results presented in Section 4.2.

Date 1 | Date 2 | Track Number | B_{⊥} (m) | Bt (day) | Configuration | Code |
---|---|---|---|---|---|---|

10/02/16 | 11/01/17 | 18 | 94.7 | 336 | Ascending | a1 |

05/05/17 | 01/03/18 | 18 | 27.1 | 300 | Ascending | a2 |

10/02/16 | 01/03/18 | 18 | 79.59 | 750 | Ascending | a3 |

10/02/16 | 05/05/17 | 18 | 37.45 | 450 | Ascending | a4 |

23/11/14 | 31/10/16 | 18 | 43 | 708 | Ascending | a5 |

29/04/17 | 01/03/18 | 18 | 73.44 | 306 | Ascending | a6 |

10/01/17 | 30/03/18 | 83 | 10.61 | 444 | Descending | b1 |

10/05/17 | 30/03/18 | 83 | 50.6 | 324 | Descending | b2 |

17/12/16 | 30/03/18 | 83 | 71.9 | 468 | Descending | b3 |

22/03/16 | 10/01/17 | 83 | 42.62 | 294 | Descending | b4 |

28/04/17 | 12/12/17 | 83 | 35.06 | 228 | Descending | b5 |

10/12/14 | 22/03/16 | 83 | 53.91 | 468 | Descending | b6 |

**Table 2.**Statistical values between the different source geometries tasted in the InSAR modeling for the descending and ascending interferograms. The RMS corresponds to the root mean square of the residual, and the WRSS corresponds to the residual sum squares weighted with the covariance. The DOF corresponds to the degree of freedom of the model, and finally, the AIC denotes coefficients.

Model | RMS (asc) | RMS (desc) | WRSS (asc) | WRSS (desc) | DOF | AIC (asc) | AIC (desc) |
---|---|---|---|---|---|---|---|

Mogi Point source | 0.0166 | 0.0118 | 6590.04 | 1105.00 | 0 | 776.406 | 213.272 |

Rectangular dipping sill | 0.0141 | 0.0109 | 6513.18 | 1061.53 | 4 | 781.684 | 217.981 |

Penny-shaped sill-like | 0.0148 | 0.0113 | 6576.59 | 1097.66 | 1 | 777.931 | 214.725 |

Prolate spheroid source | 0.0146 | 0.0118 | 6554.62 | 1081.22 | 4 | 783.155 | 219.488 |

Horizontal rectangular sill | 0.0143 | 0.0133 | 6527.24 | 1072.97 | 3 | 780.184 | 216.860 |

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Astort, A.; Walter, T.R.; Ruiz, F.; Sagripanti, L.; Nacif, A.; Acosta, G.; Folguera, A.
Unrest at Domuyo Volcano, Argentina, Detected by Geophysical and Geodetic Data and Morphometric Analysis. *Remote Sens.* **2019**, *11*, 2175.
https://doi.org/10.3390/rs11182175

**AMA Style**

Astort A, Walter TR, Ruiz F, Sagripanti L, Nacif A, Acosta G, Folguera A.
Unrest at Domuyo Volcano, Argentina, Detected by Geophysical and Geodetic Data and Morphometric Analysis. *Remote Sensing*. 2019; 11(18):2175.
https://doi.org/10.3390/rs11182175

**Chicago/Turabian Style**

Astort, Ana, Thomas R. Walter, Francisco Ruiz, Lucía Sagripanti, Andrés Nacif, Gemma Acosta, and Andrés Folguera.
2019. "Unrest at Domuyo Volcano, Argentina, Detected by Geophysical and Geodetic Data and Morphometric Analysis" *Remote Sensing* 11, no. 18: 2175.
https://doi.org/10.3390/rs11182175