The pre-Tertiary basement of central and south Vietnam is affected by pervasive strike-slip and
normal faulting, which appears to control the shape of the present continental margin of eastern Indochina.
Using remote sensing and field studies, we show the existence of two superposed strike-slip fault systems
which were probably active during the Paleogene and early Neogene, respectively. The older system
consists of large NW-SE left-lateral strike-slip faults, parallel to the Red River Fault, compatible with an EW
maximum shortening axis.
