Open AccessMicroearthquakes near the eastern end of St Paul's Fracture Zone
Author(s) -
Francis T. J. G.,
Porter I. T.,
Lilwall R. C.
Publication year - 1978
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.1978.tb03738.x
Subject(s) - geology , ridge , seismometer , seismology , fracture zone , lithosphere , mid atlantic ridge , mid ocean ridge , crust , fracture (geology) , oceanic crust , seafloor spreading , hydrothermal circulation , tectonics , geophysics , paleontology , subduction
Summary . Four ocean‐bottom seismographs were deployed near the eastern end of the St Paul's Fracture Zone in 1974 December. Microearthquakes were observed both along the fracture zone and in the median valley of the Mid‐Atlantic Ridge. Seventy‐six of them have been located and reliable depths obtained for 51. The range of depths observed suggests that the thickness of the lithosphere close to the ridge axis is 7 km. The absence of earthquakes on the ridge axis between 1 and 5 km depth may be the result of a highly cracked crust and thus indicates the depth to which hydrothermal fluids penetrate.