New study of the 1755 earthquake source based on multi-channel seismic survey data and tsunami modeling M. A. Baptista1,2, J. M. Miranda2, F. Chierici3,4, and N. Zitellini3 1Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emdio Navarro, 1, 1900-049 Lisboa, Portugal 2Centro de Geofisica da Universidade de Lisboa, Rua Ernesto de Vasconcelos, Faculdade de Ciências Ed. C8, 6°, 1700 Lisboa, Portugal 3Instituto di Geologia Marina, Via Gobetti, 101, Bologna 40100, Italy 4Istituto di Radioastronomia – Sez. di Matera, Contrada Terlecchia, Matera
Abstract. In the last years, large effort has
been done to carry out multi-channel seismic reflection surveys (MCS) in
SW Iberia to locate the active tectonic structures that could be related
to the generation of the 1755 Lisbon earthquake and the tsunami. The
outcome of these researches led to the identification of a large,
compressive tectonic structure, named Marques de Pombal thrust that, alone
can account for only half the seismic energy released by the 1755 event.
However, these investigations have shown the presence of additional
tectonic structures active along the continental margin of SW Iberia that
are here evaluated to model the tsunami waves observed along the coasts of
Iberia, Morocco and Central Atlantic. In this paper we present a new
reappraisal of the 1755 source, proposing a possible composite source,
including the Marques de Pombal thrust fault and the Guadalquivir Bank.
The test of the source is achieved through numerical modelling of the
tsunami all over the North Atlantic area. The results presented now
incorporate data from the geophysical cruises and the historical
observation along the European coasts and also from the Western Indies.
The results of this study will, hopefully, improve the seismic risk
assessment and evaluation in the Portuguese territory, Spain, Morocco and
Citation: Baptista, M. A., Miranda, J. M., Chierici, F., and Zitellini, N.: New study of the 1755 earthquake source based on multi-channel seismic survey data and tsunami modeling, Nat. Hazards Earth Syst. Sci., 3, 333-340, doi:10.5194/nhess-3-333-2003, 2003.