Paleoseismological investigations along the Kera fault zone, Western Crete: implications for seismic hazard assessment


Δημοσιευμένα: Jan 1, 2001
V. MOUSLOPOULOU
C. ANDREOU
Κ. ATAKAN
I. FOUNTOULIS
Περίληψη

The island of Crete is the principal landmass in the Aegean arc system. Collision of the Euroasian plate in the north and the African plate in the south gives rise to the subduction related deformation along the Hellenic arc. As a result of the complex deformation, the area is characterized by high seismic activity. Paleoseismic investigations performed along the Kera fault scarp, which is part of a N-S oriented fault system along the Spatha peninsula (NW-Crete), show clear evidence of repeated normal faulting events. Five distinct episodes of faulting are observed. The first two are probably of Middle-Miocene or younger age representing older tectonic episodes, whereas the last three indicate co-seismic displacements most likely during the Pleistocene and Holocene. This is in good agreement with the previous estimates of Holocene average slip rate and the recurrence time estimate of large earthquakes in the order of ca. lmm/yr and 3000yrs, respectively. The Kera fault represents a NE-SW oriented bend in a N-S fault system and therefore has a minor left-lateral strike-slip component. During the 1980's at least three earthquakes could be associated with the Kera fault. More recently, in 1999, there were three small (with magnitudes between 3.0-4.5) offshore events that are probably associated with the same fault system in the offshore extension (to the north) of the N-S oriented faults along the Spatha peninsula. The existence of these earthquakes as well as the recent paleoseismic results clearly demonstrates the need of revising the seismic hazard assessment of the area. The length of the N-S oriented fault system, where the Kera fault represents the middle segment, reaches to a total of 30 km., and is capable of generating an earthquake of magnitude in the range 6.0-6.7. Such a (shallow) earthquake occurring at a short distance to the densely populated north-western coast of Crete is likely to have significant consequences.

Λεπτομέρειες άρθρου
  • Ενότητα
  • Σεισμολογία
Λήψεις
Τα δεδομένα λήψης δεν είναι ακόμη διαθέσιμα.
Αναφορές
ANDREOU C, 2000. Seismic Hazard Analysis Of Western Crete And Kythira Strait, Institute of Solid Earth Physics, University of Bergen, pp. 1-180.
ARMIJO, R., LYONCAEN, H., PAPANASTASSIOU, D., 1992. East-West extension and Holocene normal-fault scarps in the Hellenic arc. Geology, vol. 20, Nr. 6, 491-494.
DRAKOPOULOS, J., FYTROLAKIS, N., DELIBASIS, N. AND MAKROPOULOS, K., 1983. The seismotectonic map of Crete. Pubi, by Technical Chamber of Greece, Div. East and West Crete, 26 pp. (in Greek).
HALL, R., AUDLEY-CHARLES, M.G AND CARTER, D.J., 1984. The significance of Crete for the evolution of eastern Mediterranean. In: J.E. Dixon and A.H.F. Robertson (Editors), The Geological Evolution of eastern Mediterranean, Spec. Iss., Geol. Soc. London, 499-516.
KNAPMEYER, M AND HARJES, H-P, 2000. Imaging crustal discontinuities and the downgoing slab beneath western Crete. Geophys. J.Int., 143, 1-21.
LE PICHON, X. AND ANGELIER, J., 1979. The Hellenic arc and trench system: a key to the neotektonic evolution of the eastern Mediterranean area. Tectonophysics, 60, 1-42.
LYON-CAEN, H., ARMIJO, R., DRAKOPOULOS, J., BASKOUTASS, J., DELIBASSIS, N., GAULON, R., KOUSKOUNA, V., LATOUSSAKIS, J., MAKROPOULOS, K, PAPADIMITRIOU, P., PAPANASTASSIOU, D., AND PEDOTTI, G, 1988. The 1986 Kalamata (South Peloponnesus) earthquake: Detailed study of a normal fault, evidences for east-west extension in the Hellenic arc: Journal of Geophysical Research, v.93, p. 14967-15000.
McCALPIN, J., 1996. Paleo seismology, 1-585 p., Edit, by Academic press.
MAKRIS, J. 1977. Geophysical investigations of the Hellenides. Hamp. Geoph. Einz, R.A. 34, 1-124.
MANAKOU, M.V. AND TSAPANOS, T.M., 2000. Seismicity and seismic hazard parameters evaluation in the island of Crete and the surrounding area inferred from mixed data files. Tectonophysics, 321, 157-178.
MARIOLAKOS, I. AND PAPANIKOLAOU, D., 1987. Deformation pattern and relation between deformation and seismicity in the Hellenic arc. Bull. Geol. Soc. Greece, vol. XIX, p.p. 59-76, Athens.
MOUSLOPOULOU,V., 1999. Active tectonics in Western Crete and Paleoseismological investigations along the Kera fault zone. Cand. Scient. Thesis, Bergen, Norway.
PAPADOPOULOS, GA. AND KIJKO, Α., 1991. Maximum likehood estimation of earthquake hazard parameters in the Aegean area from mixed data. Tectonophysics, 185, 277-294.
PAPANIKOLAOU, D., 1999. The subduction zone along the Hellenic arc: A unique location of backward moving margins in convergent lithospheric plates. In: Scientific American (Greek version), vol.A., pp. 25-29.
PAVLAKIS, P., 1993. The strike slip tectonic regime at Southern Aegean sea as implied by combined marine geophysical survey. Bull. Geol. Soc. Greece, vol. XXVIII/3, 253-273.
PIRAZZOLI, P.A., Tho mmeret, J., Thommeret, Y, Laborel, J. and Montagionni, L.E, 1982. Crustal block movements from Holocene shorelines: Crete and Antikythira (Greece). Tectonophysics, 86, 27-43.
WELLS, D.L. AND COPPERSMITH, K.J., 1994. Empirical relationships among magnitude, rupture length, rupture area, and surface displacement. Bull. Seismo. Soc. Am. 84, 974-1784.
Τα περισσότερο διαβασμένα άρθρα του ίδιου συγγραφέα(s)