Observing Etna volcano dynamics through seismic and deformation patterns

Geophysical data provide the chance to investigate a volcano's dynamics; considerable information can especially be gleaned on the stress and strain patterns accompanying the internal processes and the effect of magma ascent on the main structures triggering earthquakes. Here, we analysed in detail the seismicity recorded over the last two decades on Etna volcano (southern Italy), focusing on earthquakes distribution and focal mechanism clustering; the ground deformation pattern affecting the volcanic edifice with the inflation and deflation phases was also examined. Analysed data were compared in order to shed light on possible relationships with the volcanic activity and to better understand the internal dynamics of the volcano over time. Significant steps during or shortly before major eruptions in the seismic strain release and ground deformation temporal series highlight a straightforward relationship between seismicity occurring at shallow level, inflation/deflation and volcanism. Furthermore, at depths greater than 5-7 km, down to about 20 km, the orientation of the P- and T-axes clearly indicate the existence of a pressure source in the central part of the volcano. All the results underline that the stress field related to the volcano plumbing system interferes with the regional field, partly overriding it.

INGV-Ricerca Libera 2021
INGV-IMPACT

1. Hill, D. P., Pollitz, F. & Newhall, C. Earthquake-volcano interactions. Phys. Today 55, 41–47. https:// doi. org/ 10. 1063/1. 15350 06
(2002).
2. Walter, T. R., Acocella, V., Neri, M. & Amelung, F. Feedback processes between magmatic events and flank movement at Mount
Etna (Italy) during the 2002–2003 eruption. J. Geophys. Res. Solid Earth 110, B10205. https:// doi. org/ 10. 1029/ 2005J B0036 88 (2005).
3. Alparone, S., Barberi, G., Bonforte, A., Maiolino, V. & Ursino, A. Evidence of multiple strain fields beneath the eastern flank of
Mt. Etna volcano (Sicily, Italy) deduced from seismic and geodetic data during 2003–2004. Bull. Volcanol. 73, 869–885. https://
doi. org/ 10. 1007/ s00445- 011- 0456-1 (2011).
4. Patane, D. & Privitera, E. Seismicity related to 1989 and 1991–93 Mt. Etna (Italy) eruptions: Kinematic constraints by fault plane
solution analysis. J. Volcanol. Geotherm. Res. 109, 77–98. https:// doi. org/ 10. 1016/ S0377- 0273(00) 00305-X (2001).
5. Sanchez, J. J., Wyss, M. & McNutt, S. R. Temporal-spatial variations of stress at Redoubt volcano, Alaska, inferred from inversion
of fault plane solutions. J. Volcanol. Geotherm. Res. 130, 1–30. https:// doi. org/ 10. 1016/ S0377- 0273(03) 00224-5 (2004).
6. Roman, D. C., Neuberg, J. & Luckett, R. R. Assessing the likelihood of volcanic eruption through analysis of volcanotectonic
earthquake fault-plane solutions. Earth Planet. Sci. Lett. 248, 244–252. https:// doi. org/ 10. 1016/j. epsl. 2006. 05. 029 (2006).
7. Terakawa, T. et al. Monitoring eruption activity using temporal stress changes at Mount Ontake volcano. Nat. Commun. 7, 10797.
https:// doi. org/ 10. 1038/ ncomm s10797 (2016).
8. Dzurisin, D. Volcano Deformation: Geodetic Monitoring Tecniques (Springer, 2007).
9. Bruno, V. et al. Ground deformations and volcanic processes as imaged by CGPS data at Mt. Etna (Italy) between 2003 and 2008.
J. Geophys. Res. Solid Earth 117, B07208. https:// doi. org/ 10. 1029/ 2011J B0091 14 (2012).
10. Cannavò, F. et al. Real time tracking of magmatic intrusions by means of ground deformation modeling during volcanic crises.
Sci. Rep. 5, 10970. https:// doi. org/ 10. 1038/ srep1 0970 (2015).
11. Bonaccorso, A. & Aloisi, M. Tracking magma storage: New perspectives from 40 years (1980–2020) of ground deformation source
modeling on Etna Volcano. Front. Earth Sci. 9, 638742. https:// doi. org/ 10. 3389/ feart. 2021. 638742 (2021).
12. Lengliné, O. et al. Seismicity and deformation induced by magma accumulation at three basaltic volcanoes. J. Geophys. Res. Solid
Earth 113, B12305. https:// doi. org/ 10. 1029/ 2008J B0059 37 (2008).
13. Cesca, S. et al. Drainage of a deep magma reservoir near Mayotte inferred from seismicity and deformation. Nat. Geosci. 13, 87–93.
https:// doi. org/ 10. 1038/ s41561- 019- 0505-5 (2020).
14. del Fresno, C. et al. Magmatic plumbing and dynamic evolution of the 2021 La Palma eruption. Nat. Commun. 14, 358. https://
doi. org/ 10. 1038/ s41467- 023- 35953-y (2023).
15. Doglioni, C., Innocenti, F. & Mariotti, S. Why Mt. Etna?. Terra Nova 13(1), 25–31. https:// doi. org/ 10. 1046/j. 1365- 3121. 2001.
00301.x (2001).
16. Barreca, G. et al. Slab detachment, mantle flow, and crustal collision in eastern Sicily (Southern Italy): Implications on Mount Etna
volcanism. Tectonics 39, e2020TC006188. https:// doi. org/ 10. 1029/ 2020T C0061 88 (2020).
17. Monaco, C. et al. The seismogenic source of the 2018 December 26th earthquake (Mt. Etna, Italy): A shear zone in the unstable
eastern flank of the volcano. J. Geodyn. 143, 101807. https:// doi. org/ 10. 1016/j. jog. 2020. 101807 (2021).
18. Barberi, G., Cocina, O., Maiolino, V., Musumeci, C. & Privitera, E. Insight into Mt. Etna (Italy) kinematics during the 2002–2003
eruption as inferred from seismic stress and strain tensors. Geophys. Res. Lett. 31, L21614. https:// doi. org/ 10. 1029/ 2004G L0209
18 (2004).
19. Scarfì, L., Messina, A. & Cassisi, C. Sicily and Southern Calabria focal mechanism database: A valuable tool for the local and
regional stress-field determination. Ann. Geophys. 56(1), D0109. https:// doi. org/ 10. 4401/ ag- 6109 (2013).
20. Alparone, S. et al. Seismological constraints on the 2018 Mt. Etna (Italy) flank eruption and implications for the flank dynamics
of the volcano. Terra Nova 32, 334–344. https:// doi. org/ 10. 1111/ ter. 12463 (2020).
21. Solaro, G. et al. Anatomy of an unstable volcano from InSAR: Multiple processes affecting flank instability at Mt. Etna, 1994–2008.
J. Geophys. Res. Solid Earth 115, B10405. https:// doi. org/ 10. 1029/ 2009J B0008 20 (2010).
22. Bonforte, A., Guglielmino, F., Coltelli, M., Ferretti, A. & Puglisi, G. Structural assessment of Mount Etna volcano from permanent
scatterers analysis. Geochem. Geophys. Geosyst. 12, Q02002. https:// doi. org/ 10. 1029/ 2010G C0032 13 (2011).
23. Apuani, T., Corazzato, C., Merri, A. & Tibaldi, A. Understanding Etna flank instability through numerical models. J. Volcanol.
Geotherm. Res. 251, 112–126. https:// doi. org/ 10. 1016/j. jvolg eores. 2012. 06. 015 (2013).
24. Harris, A., Steffke, A., Calvari, S. & Spampinato, L. Thirty years of satellite-derived lava discharge rates at Etna: Implications for
steady volumetric output. J. Geophys. Res. Solid Earth 116, B08204. https:// doi. org/ 10. 1029/ 2011J B0082 37 (2011).
25. Behncke, B. et al. Lidar surveys reveal eruptive volumes and rates at Etna, 2007–2010. Geophys. Res. Lett. 43, 4270–4278. https://
doi. org/ 10. 1002/ 2016G L0684 95 (2016).
26. Andronico, D., Cannata, A., Di Grazia, G. & Ferrari, F. The 1986–2021 paroxysmal episodes at the summit craters of Mt. Etna:
Insights into volcano dynamics and hazard. Earth Sci. Rev. 220, 103686. https:// doi. org/ 10. 1016/j. earsc irev. 2021. 103686 (2021).
27. Bruno, V. et al. The most intense deflation of the last two decades at Mt. Etna: The 2019–2021 evolution of ground deformation
and modelled pressure sources. Geophys. Res. Lett. 49, e2021GL095195. https:// doi. org/ 10. 1029/ 2021G L0951 95 (2022).
28. Bonforte, A., Bonaccorso, A., Guglielmino, F., Palano, M. & Puglisi, G. Feeding system and magma storage beneath Mt. Etna as
revealed by recent inflation/deflation cycles. J. Geophys. Res. Solid Earth 113, B05406. https:// doi. org/ 10. 1029/ 2007J B0053 34 (2008).
29. Aloisi, M. et al. Imaging the multi-level magma reservoir at Mt. Etna volcano (Italy). Geophys. Res. Lett. 38, L16306. https:// doi.
org/ 10. 1029/ 2011G L0484 88 (2011).
30. Aloisi, M., Bonaccorso, A., Cannavò, F. & Currenti, G. M. Coupled short- and medium-term geophysical signals at Etna volcano:
Using deformation and strain to infer magmatic processes from 2009 to 2017. Front. Earth Sci. 6, 109. https:// doi. org/ 10. 3389/
feart. 2018. 00109 (2018).
31. Patanè, D., Barberi, G., Cocina, O., De Gori, P. & Chiarabba, C. Time-resolved seismic tomography detects magma intrusions at
Mount Etna. Science 313(5788), 821–823. https:// doi. org/ 10. 1126/ scien ce. 11277 24 (2006).
32. Bertiger, W. et al. GipsyX/RTGx, a new tool set for space geodetic operations and research. Adv. Space Res. 66(3), 469–489. https://
doi. org/ 10. 1016/j. asr. 2020. 04. 015 (2020).
33. Barreca, G., Corradino, M., Pepe, F. & Monaco, C. Active tectonics along the south east offshore margin of Mt. Etna: New insights
from high-resolution seismic profiles. Geosciences 8(2), 62. https:// doi. org/ 10. 3390/ geosc ience s8020 062 (2018).
34. Gonzalez, P. J. & Palano, M. Mt. Etna 2001 eruption: New insights into themagmatic feeding system and the mechanical response
of the western flankfrom a detailed geodetic dataset. J. Volcanol. Geotherm. Res. 274, 108–121. https:// doi. org/ 10. 1016/j. jvolg eores.
2014. 02. 001 (2014).
35. Palano, M. Episodic slow slip events and seaward flank motion at Mt. Etna volcano (Italy). J. Volcanol. Geotherm. Res. 324, 8–14.
https:// doi. org/ 10. 1016/j. jvolg eores. 2016. 05. 010 (2016).
36. Palano, M., Viccaro, M., Zuccarello, F. & Gresta, S. Magma transport and storage at Mt. Etna (Italy): A review of geodetic and
petrological data for the 2002–03, 2004 and 2006 eruption. J. Volcanol. Geotherm. Res. 347, 149–164. https:// doi. org/ 10. 1016/j.
jvolg eores. 2017. 09. 009 (2017).
37. Alparone, S. C. et al. Mt. Etna Seismic Catalog 2000–2010. Istituto Nazionale di Geofisica e Vulcanologia (INGV); https:// doi. org/
10. 13127/ etnasc/ 2000_ 2010 (2015).
38. Alparone, S. C. et al. Mt. Etna Seismic Catalog 2011–2013 (Version 1). Istituto Nazionale di Geofisica e Vulcanologia (INGV); https://
doi. org/ 10. 13127/ ETNASC/ 2011_ 2013 (2020).
39. Alparone, S. C. et al. Mt. Etna Seismic Catalog 2014–2016 (Version 1). Istituto Nazionale di Geofisica e Vulcanologia (INGV); https://
doi. org/ 10. 13127/ ETNASC/ 2014_ 2016 (2020).
40. Alparone, S. C. et al. Mt. Etna Seismic Catalog 2017–2019 (Version 1). Istituto Nazionale di Geofisica e Vulcanologia (INGV); https://
doi. org/ 10. 13127/ ETNASC/ 2017_ 2019 (2022).
41. Barberi, G. et al. Mt. Etna Revised Seismic Catalog from 2020 (EtnaRSC2020) (Version 1). Istituto Nazionale di Geofisica e Vulcanologia
(INGV); https:// doi. org/ 10. 13127/ ETNASC/ ETNAR SC2020 (2020).
42. Zhang, H., Thurber, C. & Bedrosian, P. Joint inversion for Vp, Vs, and Vp/Vs at SAFOD, Parkfield, California. Geochem. Geophys.
Geosyst. 10, Q110032. https:// doi. org/ 10. 1029/ 2009G C0027 09 (2009).
43. Firetto Carlino, M. et al. Frequency-magnitude distribution of earthquakes at Etna volcano unravels critical stress changes along
magma pathways. Commun. Earth Environ. 3, 68. https:// doi. org/ 10. 1038/ s43247- 022- 00398-6 (2022).
44. Lavecchia, G., Ferrarini, F., de Nardis, R., Visini, F. & Barbano, S. Active thrusting as a possible seismogenic source in Sicily
(Southern Italy): Some insights from integrated structural-kinematic and seismological data. Tectonophysics 445(3–4), 145–167.
https:// doi. org/ 10. 1016/j. tecto. 2007. 07. 007 (2007).
45. De Guidi, G. et al. Geological, seismological and geodetic evidence of active thrusting and folding south of Mt. Etna (eastern Sicily):
Revaluation of “seismic efficiency” of the Sicilian Basal Thrust. J. Geodyn. 90, 32–41. https:// doi. org/ 10. 1016/j. jog. 2015. 06.
001 (2015).
46. Richter, C. F. Elementary Seismology (W. H. Freeman & Company, 1958).
47. Scarfì, L., Langer, H., Messina, A. & Musumeci, C. Tectonic regimes inferred from clustering of focal mechanisms and their distribution
in space: Application to the Central Mediterranean Area. J. Geophys. Res. Solid Earth 126, e2020JB020519. https:// doi.
org/ 10. 1029/ 2020J B0205 19 (2021).
48. Cesca, S., Sen, A. T. & Dahm, T. Seismicity monitoring by cluster analysis of moment tensors. Geophys. J. Int. 196(3), 1813–1826.
https:// doi. org/ 10. 1093/ gji/ ggt492 (2014).
49. Alparone, S. et al. Intrusive mechanism of the 2008–2009 Mt. Etna eruption: Constraints by tomographic images and stress tensor
analysis. J. Volcanol. Geotherm. Res. 229–230, 50–63. https:// doi. org/ 10. 1016/j. jvolg eores. 2012. 04. 001 (2012).
50. Alparone, S. et al. Seismological features of the Pernicana-Provenzana Fault System (Mt. Etna, Italy) and implications for the
dynamics of northeastern flank of the volcano. J. Volcanol. Geotherm. Res. 251, 16–26. https:// doi. org/ 10. 1016/j. jvolg eores. 2012.
03. 010 (2013).
51. Musumeci, C., Scarfì, L., Palano, M. & Patanè, D. Foreland segmentation along an active convergent margin: New constraints in
southeastern Sicily (Italy) from seismic and geodetic observations. Tectonophysics 630, 137–149. https:// doi. org/ 10. 1016/j. tecto.
2014. 05. 017 (2014).
52. Scarfì, L., Barberi, G., Musumeci, C. & Patanè, D. Seismotectonics of Northeastern Sicily and Southern Calabria (Italy): New constraints
on the tectonic structures featuring in a crucial sector for the Central Mediterranean geodynamics. Tectonics 35, 812–832.
https:// doi. org/ 10. 1002/ 2015T C0040 22 (2016).
53. Reasenberg, P. & Oppenheimer, D. H. FPFIT, FPPLOT and FPPAGE: FORTRAN computer programs for calculating and displaying
earthquake fault-plane solutions. U.S. Geol. Surv., Open File Rep., 85–739; https:// doi. org/ 10. 3133/ ofr85 739 (1985).
54. Messina, A. & Langer, H. Pattern recognition of volcanic tremor data on Mt. Etna with KKAnalysis—A software program for
unsupervised classification. Comput. Geosci. 37(7), 953–961. https:// doi. org/ 10. 1016/j. cageo. 2011. 03. 015 (2011).
55. Langer, H., Falsaperla, S. & Hammer, C. Advantages and pitfalls of pattern recognition: Selected cases in geophysics. In Computational
Geophysics Vol. 3 (Elsevier, 2020).
56. Kagan, Y. Y. Simplified algorithm for calculating double-couple rotation. Geophys. J. Int. 171(1), 411–418. https:// doi. org/ 10. 1111/j.
1365- 246X. 2007. 03538.x (2007).
57. Barreca, G., Scarfì, L., Cannavò, F., Koulakov, I. & Monaco, C. New structural and seismological evidence and interpretation of
a lithospheric-scale shear zone at the southern edge of the Ionian subduction system (central-eastern Sicily, Italy). Tectonics 35,
1489–1505. https:// doi. org/ 10. 1002/ 2015T C0040 57 (2016).
58. Barberi, G., Cocina, O., Neri, G., Privitera, E. & Spampinato, S. Volcanological inferences from seismic strain tensor computations
at Mt. Etna Volcano, Sicily. Bull. Volcanol. 62, 318–330. https:// doi. org/ 10. 1007/ s0044 50000 101 (2000).
59. Paonita, A. et al. Intense overpressurization at basaltic open-conduit volcanoes as inferred by geochemical signals: The case of the
Mt. Etna December 2018 eruption. Sci. Adv. https:// doi. org/ 10. 1126/ sciadv. abg62 97 (2021).
60. Ryan, W. B. F. et al. Global Multi-Resolution Topography (GMRT) synthesis data set. Geochem. Geophys. Geosyst. 10, Q03014.
https:// doi. org/ 10. 1029/ 2008G C0023 32 (2009).