Abstract
The seismic attenuation in the Vrancea region (Romania) is investigated from teleseismic recordings of P and pP waves during the four major, intermediate-depth Romanian events that occurred since the onset of digital instrumentation. Most stations are located in Canada and in the United States, being equipped with a variety of sensors, especially short-period ones. The amplitude spectral ratio method is used, assuming no frequency dependence of the Q P factor in the range 0.2–2 Hz. No apparent correlation between the derived attenuation value and the type of recording sensor is observed. Lateral variations of the attenuation are obtained, with a very low Q P area (values down to 33) located in the northwestern part of the Vrancea seismogenic volume. For the stations with different azimuth angles in relation to the epicentral area, Q P values routinely exceed 200. Most likely, the low attenuation values are related to an upwelling mantle material located immediately beneath the crust, but limited in depth to at least 100 km.
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References
Anderson DL, Hart RS (1978) Attenuation models of the Earth. Phys Earth Planet Inter 16:289–306
Bhattacharyya J, Masters G, Shearer P (1996) Global lateral variations of shear wave attenuation in the upper mantle. J Geophys Res 101:22273–22289
Bock G, Clements JR (1982) Attenuation of Short-period P, PcP, ScP and pP Waves in the Earth’s Mantle. J Geophys Res 87:3905–3918
Bonjer K-P, Oncescu MC, Rizescu M, Enescu D, Driad L, Radulian M, Ionescu C, Moldoveanu T (2000) Source- and site-parameters of the April 28, 1999 intermediate depth Vrancea earthquake: first results from the new K2 network in Romania, XXVII General Assembly of the European Seismological Commission, Lisbon, Portugal, Book of Abstracts and Papers, SSA-2-13-O 53
Chalot-Prat F, Gîrbacea R (2000) Partial delamination of continental mantle lithosphere, uplift-related crust–mantle decoupling, volcanism and basin formation: a new model for the Pliocene–Quaternary evolution of the southern East-Carpathians, Romania. Tectonophysics 327:83–107
Cloething SAPL, Burov E, Matenco L, Toussaint G, Bertotti G, Andriessen PAM, Wortel MJR, Spakman W (2004) Thermo-mechanical controls on the mode of continental collision in the SE Carpathians (Romania). Earth Planet Sci Lett 218:57–76
Csontos L (1995) Tertiary tectonic evolution of the Intra-Carpathian area: a review. Acta Vulcanol 7:4–43
Eberhart-Phillips D, Reyners M, Chadwick M, Chiu J-M (2005) Crustal heterogeneity and subduction processes: 3-D V P, V P/V s and Q in the southern North Island, New Zealand. Geophys J Int 162:270–288
Enescu D (1985) Phase change – a possible process involved in preparing the occurrence of Vrancea earthquakes. Rev Roum Geol Géophys Geogr Ser Geophys 29:15–21
Enescu D (2003) Contributions to the understanding of the directivity of Vrancea earthquake foci. Considerations on some results of seismic tomography performed in Romania. Rom J Phys 48:953–969
Enescu D, Enescu B (1993) A new model regarding the subduction process in the Vrancea zone. Rom J Phys 38:321–328
Fan G, Wallace TC, Zhao D (1998) Tomographic imaging of deep velocity structure beneath the Eastern and Southern Carpathians, Romania: implications for continental collision. J Geophys Res 1023:2705–2723
Flanagan MP, Wiens DA (1998) Attenuation of broadband P and S waves in Tonga: observations of frequency dependent Q. Pure Appl Geophys 153:345–375
Fuchs K, Bonjer K-P, Bock G, Cornea I, Radu C, Enescu D, Jianu D, Nourescu A, Merkler G, Moldoveanu T, Tudorache G (1979) The Romanian earthquake of March 4, 1977: II. Aftershocks and migration of seismic activity. Tectonophysics 53:225–247
Gîrbacea R, Frisch W (1998) Slab in the wrong place: lower lithospheric mantle delamination in the last stage of the Eastern Carpathian subduction retreat. Geology 26:611–614
Gvirtzman Z (2002) Partial detachment of a lithospheric root under the southeast Carpathians: toward a better definition of the detachment concept. Geology 30:51–54
Hauser F, Raileanu V, Fielitz W, Bala A, Prodehl C, Polonic G, Schulze A (2001) VRANCEA99 – the crustal structure beneath southeastern Carpathians and Moesian Platform from a seismic refraction profile in Romania. Tectonophysics 340:233–256
Ismail-Zadeh AT (2003) Modelling of the stress and seismicity in the Southeastern Carpathians. In: Beer T, Ismail-Zadeh AT (eds) Risk Science and Sustainability. Kluwer Academic Publishers, Dordrecht, Netherlands, pp149–162
Ivan M (2003a) Short-period QpP–P in Vrancea area, Romania. J Balkan Geophys Soc 6:46–52
Ivan M (2003b) Q S–P in Vrancea and adjacent areas – Romania. St Cerc Geofiz 41:57–63
Kissling E, Ellsworth WL, Eberhart-Phillips D, Kradolfer U (1994) Initial reference models in seismic tomography. J Geophys Res 99:19635–19646
Linzer H-G, Frisch W, Zweigel P, Gîrbacea R, Hann H-P, F Moser F (1998) Kinematic evolution of the Romanian Carpathians. Tectonophysics 297:133–156
Martin M, Ritter JRR, the CALIXTO working group (2005) High-resolution teleseismic body-wave tomography beneath SE Romania – I. Implications for three-dimensional versus one-dimensional crustal correction strategies with a new crustal velocity model. Geophys J Int 162:448–460
Mason PRD, Seghedi I, Szakacs A, Downes H (1998) Magmatic constraints on geodynamic models of subduction in the East Carpathians (Romania). Tectonophysics 297:157–176
Oncescu MC (1980) Multipolar analysis of the March 4, 1977 Vrancea earthquake. Boll Geofiz Teor Appl XXII 88:303–309
Oncescu MC (1984) Deep structure of Vrancea region, Romania, inferred from simultaneous inversion for hypocenters and 3-D velocity structure. Ann Geophys 2:23–28
Popa M, Radulian M, Grecu B, Popescu E, Placinta AO (2005) Attenuation on Southeastern Carpathians area: result of upper mantle inhomogeneity. Tectonophysics 410:235–249
Roth EG, Wiens DA, Dorman LM, Hildebrand J, Webb SC (1999) Seismic attenuation tomography of the Tonga–Fiji region using phase pair methods. J Geophys Res 104:4795–4809
Sailor RV, Dziewonski AM (1978) Measurement and interpretation of normal mode attenuation. Geophys J R Astron Soc 53:559–581
Seghedi I, Balintoni I, Szakacz A (1998) Interplay of tectonics and Neogene post-collisional magmatism in the intra-Carpathian region. Lithos 45:483–497
Sipkin SA, Jordan TH (1980) Regional variation of Q ScS. Bull Seismol Soc Am 70:1071–1102
Sperner B, Lorentz F, Bonjer K-P, Hettel S, Müller B, Wenzel F (2001) Slab break-off – abrupt cut or gradual detachment? New insights from Vrancea region (SE-Carpathians, Romania). Terra Nova 13:172–179
Stearn SD (1975) Digital Signal Analysis. Hayden Book, New Jersey
Sudhaus H, Ritter JRR (2005) High-resolution measurement of the seismic attenuation across the Vrancea region, Romania. Geophys Res Lett 32:L10301 doi: 10.1029/2004GL022148
Wessel P, Smith WHF (1996) A global, self-consistent, hierarchical, high-resolution shoreline database. J Geophys Res 101:8741–8743
Wortel R, Spakman W (2000) Subduction and slab detachment in the Mediterranean–Carpathian region. Science 290:1910–1917
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Ivan, M. Attenuation of P and pP waves in Vrancea area – Romania. J Seismol 11, 73–85 (2007). https://doi.org/10.1007/s10950-006-9038-7
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DOI: https://doi.org/10.1007/s10950-006-9038-7