Open AccessSeismic reflections from the Moho ‐ the effect of isostasy
Author(s) -
Warner M. R.
Publication year - 1987
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1987.tb06651.x
Subject(s) - isostasy , geology , crust , lithosphere , seismology , reflection (computer programming) , mantle (geology) , geophysics , geodesy , tectonics , programming language , computer science
Summary Deep seismic reflection profiling has become an established technique for studying the continental lithosphere. The base of the crust can be identified on many deep profiles and it correlates closely with the Moho determined by refraction studies. On many reflection profiles the Moho appears at a rather constant two‐way travel time despite the highly variable structure of the crust above. It is shown that the apparent flatness of the Moho on reflection time sections is an artefact produced when the crust is in local isostatic equilibrium. The true geometry of the Moho can only be determined if accurate and spatially well‐resolved seismic velocities are obtained from the lower crust. The degree of isostatic compensation can be assessed from deep reflection data and an equivalent elastic thickness calculated. The elastic thickness around the UK is very small, only 2–3 km. It is suggested that the many major fault zones visible on the seismic data weaken the lithosphere to produce these low values.