Open AccessA microearthquake survey at the junction of the East Pacific Rise and the Wilkes (9°S) fracture zone
Author(s) -
Lilwall R. C.,
Francis T. J. G.,
Porter I. T.
Publication year - 1981
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.1981.tb05962.x
Subject(s) - microearthquake , geology , seismology , seismometer , crest , magma chamber , crust , fracture zone , magma , induced seismicity , volcano , geophysics , physics , quantum mechanics
Summary. An ocean bottom seismograph survey of the junction of the East Pacific Rise and the Wilkes fracture zone detected only three microearthquakes beneath the rise crest during seven days of recording. In contrast, during the same period 41 events were detected on the fracture zone, all at distances greater than 10 km from the junction. These results suggest that near the rise crest the thin crust can support sufficient stress only to generate infrequent small earthquakes and that most faulting may take place by aseismic slip. At 10 km from the rise axis part of the crest has become competent enough to support stress, resulting in earthquakes probably at depths of up to 5 km below the sea‐bed. Gear 5‐waves on the seismometer records indicate that a magma chamber, if it exists near the junction, is less than 10 km across.