Site effects in archaeoseismic studies at Mycenaean Tiryns and Midea

• Autores: Klaus-G. Hinzen, Hector R. Hinojosa-Prieto, Tatiana Kalytta
• Localización: Seismological Research Letters, ISSN 0895-0695, ISSN-e 1938-2057, Vol. 87, Nº. 5, 2016, págs. 1060-1074
• Idioma: inglés
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• Resumen

  • The hypothesis that major Mycenaean settlements were devastated by earthquakes at the end of the Late Bronze Age is based on archaeological observations. To test this hypothesis with engineering seismological methods, the local site conditions and their influence on earthquake ground motions should be known. We used active and passive seismic measurements to deduce earthquake site effects at the Mycenaean citadels of Tiryns and Midea in the Argive basin on the eastern Peloponnese.

    At 182 station locations and with six arrays, we recorded ambient noise data from which Rayleigh-wave ellipticity curves and dispersion functions were calculated, respectively. In addition, local earthquake data from a nine-month deployment of 10 stations were used to calculate standard spectral ratios. 1D models were used to calculate amplification functions for the citadels and their surroundings. Although the shallow double limestone knoll of Tiryns, which contained the Mycenaean palace and carries a massive Cyclopean fortification wall, shows only small site amplifications below a factor of 2 at frequencies between 2 and 10 Hz, the soft sediment in the surrounding area where the peasant residences were located has amplifications of 4–6. At the Midea citadel, erected on a 270-m-high hill, the topography results in ground-motion amplifications of a factor of 2–3 at frequencies between 1 and 3 Hz.