pure and applied geophysics

, Volume 125, Issue 6, pp 883–917 | Cite as

Seismic sources and attenuation properties at the Campi Flegrei volcanic area

  • G. De Natale
  • G. Iannaccone
  • M. Martini
  • A. Zollo
Article

Abstract

Microearthquake digital data collected at Campi Flegrei during the recent (1982–1985) ground uplift episode have been analyzed in order to infer source and medium seismic properties. The main results obtained from these analyses are:
  1. 1.

    Hypocenter distribution and the size of the seismic zone do not change with time and do not depend on the ground uplift rate. Events occurred clustered in time with no simple causal relations between the cluster occurrences and their energy.

     
  2. 2.

    Anelastic attenuation does not depend strongly on frequency, showing a constant pattern at high frequencies. The observed values of low and high frequency attenuation, due to the short source receiver distances, do not seriously affect the spectral content of signals radiated by the sources.

     
  3. 3.

    A constant Brune stress drop pattern (∼4–5 bars) as a function of seismic moment is observed. This indicates that the manner of fracturing is almost independent on magnitude of earthquakes (hypothesis of self-similarity (Aki, 1967)). Seismic processes in a prefractured medium can explain the observed small stress drop values.

     
  4. 4.

    Focal mechanisms from moment tensor estimates show that radiation patterns are mostly well interpreted in terms of double couple source models.

     
  5. 5.

    The scaling of peak ground motion parameters (Amax andVmax vs seismic moment) can be explained by an ω2 source model (constant stress drop) multiplied by an exponential function with a small decay parameter, which takes into account the measured attenuation.

     

These results support the hypothesis of earthquakes generated by simple shear fractures along prefractured structures as a response to changes in the stress field due to the ground deformation.

Key words

Campi Flegrei Volcanic earthquakes Attenuation Source parameters Moment tensor 

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References

  1. Aki, K. (1967),Scaling law of seismic spectrum. J. Geophys. Res.72, 1217–1231.Google Scholar
  2. Aki, K. (1986),Physical theory of earthquakes. Proceedings of Strasbourg, 1986 Summer School on ‘Seismic hazard in mediterranean regions’ (in press).Google Scholar
  3. Aki, K. andChouet, B. (1975),Origin of coda waves: source, attenuation, and scattering effects. J. Geophys. Res.80, 3332–3342.Google Scholar
  4. Aki, K., andRichards, P. G. (1980),Quantitative seismology: theory and methods. (W. H. Freeman and Co., S. Francisco, CA).Google Scholar
  5. Anderson, J. G. andHough, S. (1984),A model for the shape of the Fourier amplitude spectrum of acceleration at high frequencies. Bull. Seism. Soc. Am.74, 1969–1994.Google Scholar
  6. Archuleta, R. J., Cranswick, E., Mueller, C. andSpudich, P. (1982),Source parameters of the 1980 Mammoth Lakes, California earthquake sequence. J. Geophys. Res.87, 4595–4607.Google Scholar
  7. Aster, R. (1987),Hypocenter locations and velocity structure in Phlegraean Fields, Italy. Master Sc. (Geophysics) Thesis, U. Wisconsin, Madison USA.Google Scholar
  8. Barberi, F., Innocenti, F., Lirer, L., Munno, R., Pescatore, T. andSantacroce, R. (1978),The campanian ignimbrite: a major prehistoric eruption in the neapolitan area (Italy). Bull. Volc.41, 1–22.Google Scholar
  9. Berrino, G., Corrado, G., Luongo, G. andToro, B. (1984),Ground deformation and gravity changes accompanying the 1982 Pozzuoli uplift. Bull. Volc.47 (2), 187–200.Google Scholar
  10. Boatwright, J. (1978),Detailed spectral analysis of two small New York State earthquakes. Bull. Seism. Soc. Am.68, 1117–1131.Google Scholar
  11. Boatwright, J. (1980),A spectral theory for circular seismic sources: simple estimates of source dimension, dynamic stress drop and radiated energy. Bull. Seism. Soc. Am.71, 69–94.Google Scholar
  12. Boore, D. M. (1983),Stochastic simulation of high frequency ground motions based on seismological models of the radiated spectra. Bull. Seism. Soc. Am.73, 1865–1894.Google Scholar
  13. Boore, D. M. andBoatwright, J. (1984),Average body wave radiation coefficients. Bull. Seism. Soc. Am.74, 1615–1621.Google Scholar
  14. Brune, J. N. (1970),Tectonic stress and the spectra of seismic shear waves from earthquakes. Bull. Seism. Soc. Am.60, 4997–5009.Google Scholar
  15. Castellano, M., Del Pezzo, E., De Natale, G. andZollo, A. (1984).Seismic coda Q and turbidity coefficient at the Phlegraean Fields volcanic area: preliminary results. Bull. Volc.47, 219–224.Google Scholar
  16. Chouet, B., Aki, K. andTsujura, M. (1978),Regional variation of the scaling law of earthof earthquake source spectra. Bull. Seism. Soc. Am.68, 49–80.Google Scholar
  17. Chouet, B. (1979),Sources of seismic events in the cooling lava lake of Kilauea Iki, Hawaii. J. Geophys. Res.84, 2315–2330.Google Scholar
  18. Clearbout, J. (1976),Fundamentals of geophysical data processing (McGraw Hill, S. Francisco, 1976).Google Scholar
  19. Corrado, G., Guerra, I., Lo Bascio, A., Luongo, G. andRampoldi, R. (1976),Inflation and microearthquake activity at Phlegraean Fields, Italy. Bull. Volc.40, 1–20.Google Scholar
  20. Crosson, R. S. (1981),LQUAKE: a computer program for hypocenter locations. Techn. Rep. Univ. Wash. (Seattle).Google Scholar
  21. Crosson, R. S. andBame, D. A. (1986),A spherical source model for low frequency volcanic earthquakes. J. Geophys. Res.92, 10237–10247.Google Scholar
  22. Dainty, A. M. (1981),Scattering model to explain seismic Q observations in the litosphere between 1 and 30 Hz. Geophys. Res. Lett.8, 1126–1128.Google Scholar
  23. Del Pezzo, E., De Natale, G. andZollo, A. (1984),Space-Time distribution of small earthquakes at Phlegraean Fields. Bull. Volc.47, 201–207.Google Scholar
  24. Del Pezzo, E., De Natale, G., Scarcella, G. andZollo, A. (1985),Q c of three component seismograms of volcanic microearthquakes at Campi Flegrei volcanic area, Southern Italy. PAGEOPH123, 683–696.Google Scholar
  25. Del Pezzo, E., De Natale, G., Martini, M. andZollo, A. (1987),Source parametersoof microearthquakes at Phlegraean Fields (Southern Italy) volcanic area. Phys. Earth Pla. Int.47, 25–42.Google Scholar
  26. De Natale, G., Iannaccone, G. andZollo, A. (1986),Un metodo per la determinazione del meccanismo focale dal tensore momento. Boll. Soc. Geol. It. (in press).Google Scholar
  27. De Natale, G., Madariaga, R., Scarpa, R. andZollo, A. (1987a),Source parameter analysis from strong motion records of the Friuli (Italy) earthquake sequence (1976–1977). Bull. Seism. Soc. Am.77, 1127–1146.Google Scholar
  28. De Natale, G., Faccioli, E. andZollo, A. (1987b),Scaling of peak, ground motions from digital recordings of small earthquakes at Campi Flegrei, Southern Italy. PAGEOPH (in press).Google Scholar
  29. De Natale G. andZollo, A. (1986),Statistical analysis and clustering features of the Phlegraean Fields earthquake sequence (May 1983–May 1984). Bull. Seism. Soc. Am.76, 801–814.Google Scholar
  30. Di Vito, M., Lirer, L., Mastrolorenzo, G., Rolandi, G. andScandone, R. (1985),Volcanological map of Campi Flegrei (Edited by Dipartimento di Geofisica e Vulcanologia, Universitá di Napoli).Google Scholar
  31. Fehler, M. andChouet, B. (1982),Operation of digital seismic network on Mt. St. Helens volcano and observations of long period seismic events that originate under the volcano. Geophys. Res. Letters9, 1017–1020.Google Scholar
  32. Gao, L. S., Lee, L. C., Biswas, N. N. andAki, K. (1983),Comparison of the effects between single and multiple scattering on coda waves for local earthquakes. Bull. Seism. Soc. Am.74, 337–389.Google Scholar
  33. Gaudiosi, G. andIanaccone, G. (1984),Preliminary study of stress pattern at Phlegraean Fields as inferred from focal mechanisms. Bull. Volcan.47, 225–231.Google Scholar
  34. Hanks, T. C. (1982),F max. Bull. Seism. Soc. Am.72, 1867–1879.Google Scholar
  35. Julian, B. R. andSipkin, S. (1985),Earthquake processes in the Long Valley Caldera area, California. J. Geophys. Res.90, 11155–11170.Google Scholar
  36. Keilis-Borok, V. I. (1959),On estimation of the displacement in an earthquake source dimensions. Ann. Geophys.12, 205–214.Google Scholar
  37. Lawson, C. L. andHanson, R. J. (1974),Solving least squares problems (Prentice Hall, Englewood Cliff, New Jersey, 1974).Google Scholar
  38. Madariaga, R. (1976),Dynamics of an expanding circular fault. Bull. Seism. Soc. Am.66, 639–666.Google Scholar
  39. Oncescu, M. C. (1986),Relative seismic moment tensor determination for Vrancea intermediate depth earthquakes. PAGEOPH (in press).Google Scholar
  40. Quareni, F., Bonafede, M. andDragoni, M. (1985),A viscoelastic model for ground deformation and seismic activity at Campi Flegrei, Italy. Geophys. J.R. Ast. Soc. (submitted).Google Scholar
  41. Rautian, T. G. andKhalturin, V. I. (1978),The use of coda for determination of the earthquake source spectra. Bull. Seism. Soc. Am.68, 49–80.Google Scholar
  42. Rosi, M., Sbrana, A. andPrincipe, C. (1983),The Phlegraean Fields: structural evolution, volcanic history and eruptive mechanisms. J. Volc. Geoth. Res.17, 237–288.Google Scholar
  43. Scarcella, G. (1984),Metodi di inversione di dati sismici: applicazione nel Basso Tirreno e nei Campi Flegrei. Degree in Physics, Thesis University of Naples, Italy.Google Scholar
  44. Strelitz, R. A. (1978),Moment tensor inversions and source models. Geophys. J.R. Astr. Soc.52, 359–364.Google Scholar
  45. St. Laurence, W. andQamar, A. (1979),Hydraulic transients: a seismic source in volcanoes and glaciers. Science203, 654–656.Google Scholar

Copyright information

© Birkhäuser Verlag 1987

Authors and Affiliations

  • G. De Natale
    • 1
  • G. Iannaccone
    • 2
  • M. Martini
    • 1
  • A. Zollo
    • 1
  1. 1.Osservatorio VesuvianoNapoliItaly
  2. 2.Dipartimento di Geofisica e VulcanologiaNapoliItaly

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