Tides in Earth's crust trigger small, deep quakes
Sam Wormley
> Tides in Earth's crust trigger small, deep quakes
> http://www.sciencenews.org/view/generic/id/51459/title/Tides_in_Earths_crust_trigger_small%2C_deep_quakes
> Study of one portion of the San Andreas fault finds that just a little added stress from crustal tides makes a quake more likely.
Mike Jr
> > Tides in Earth's crust trigger small, deep quakes
> > Study of one portion of the San Andreas fault finds that just a little added stress from crustal tides makes a quake more likely.
"The fault’s extreme sensitivity to small changes in stress suggests
that the deep portions of the fault where these small quakes occur is
well lubricated, probably by water that is under exceedingly high
pressure, the researchers suggest."
Maybe, and maybe not. From http://www.geos.ed.ac.uk/homes/scrampin/opinion/Crampin_etal.%282009%29.pdf
"the recognition that almost all in situ rocks, certainly in the
crust, and the seismogenic parts of the mantle are pervaded by self-
organised scale-invariant systems of fractures ranging from open fluid-
saturated grain-boundary microcracks and preferentially-oriented pore
space from sub-millimetre to millimetre scales to plate-boundaries at
scales of thousands of kilometres (Crampin and Peacock, 2008; Heffer
and Bevan, 1990). In the crust, the fluids are usually water-based
salt solutions, but may be hydrocarbons, and in the upper mantle,
‘fluids’ are likely to be intergranular films of hydrologised melt
(Crampin et al., 1986; Crampin, 2003a) Shear-wave splitting shows that
the cracks are so closely spaced they verge on fracturing and are
critical-systems (Crampin, 2006), and are a New Physics (Davis, 1989),
or New Geophysics. The criticality, particularly of small-scale
microcracks, is the underlying reason for rocks’ extreme sensitivity
to small disturbances."
--Mike Jr.