The power of intuition (Selwyn’s that is). Selwyn’s career goal #__: What does the asthenosphere...
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The power of intuition (Selwyn’s that is). Selwyn’s career goal #__: What does the asthenosphere have to do with earthquakes, crustal motions, and mantle
Time (years) Elastic crust Viscoelastic asthenosphere
Viscoelastic upper mantle Steve Cohen Cohen (1992) Far field Near
field Horizontal Stress
Slide 12
Physics says that the lower crust and upper mantle have to
relax the coseismic stresses imparted by an earthquake
Slide 13
A significant correlation is found, in both space and time,
between the intraplate (land) and interplate (sea, thrust zone
only) earthquakes in Tohoku, NE Japan that has persisted since the
times of reliably reported events in AD 1600. The correlation peaks
at a land-lead of about 36 yr... Earthquake-pattern inference of
rheology Rydelek and Sacks (1990) Paul Rydelek
Slide 14
Rydelek and Sacks (1990) 7.5-7.9 6.5-6.9 Magnitude 7.0-7.4
Slide 15
Rydelek and Sacks (1990)
Slide 16
Post-earthquake mantle relaxation (1896 Riku-U eq.) Rydelek and
Sacks (1990)
Slide 17
Paradigm shift in Earths continental tectonics, from
Time-independent crustal deformation, punctuated only by crustal
earthquakes and associated localized brittle/plastic deformation,
to Time-dependent crustal deformation, involving deep-seated,
ductile flow and associated broadscale deformation
Slide 18
Pollitz, F. F., and I. S. Sacks, Modeling of postseismic
relaxation following the Great 1857 Earthquake, southern
California, Bull. Seismol. Soc. Am., 82, 454-480, 1992. Pollitz, F.
F., and I. S. Sacks, Fault model of the 1891 Nobi earthquake from
historic triangulation and leveling, J. Phys. Earth, 42, 1-43,
1994. Pollitz, F. F., and I. S. Sacks, Consequences of stress
changes following the 1891 Nobi earthquake, Japan, Bull. Seismol.
Soc. Am., 85, 796-807, 1995. Pollitz, F. F., and I. S. Sacks,
Viscosity structure beneath northeast Iceland, J. Geophys. Res,
101, 17,771-17,793, 1996. Pollitz, F. F., and I. S. Sacks, The 1995
Kobe, Japan earthquake: A long-delayed aftershock of the offshore
1944 Tonankai and 1946 Nankaido earthquakes, Bull. Seismol. Soc.
Am., 87, 1- 10, 1997. Pollitz, F. F., and I. S. Sacks, Stress
triggering of the 1999 Hector Mine earthquake by transient
deformation following the 1992 Landers earthquake, Bull. Seismol.
Soc. Am. 92, 1487-1496, 2002.
Slide 19
Slide 20
Slide 21
Asthenosphere relaxation must lead to long-range transfer of
crustal stress from one fault to another
Slide 22
Slide 23
Slide 24
Slide 25
Reduced friction 1995 earthquake triggering
Slide 26
1944/1646 to 1995 postseismic stress change bars
Slide 27
Pollitz and Sacks (1997)Heinze and Sacks (1979)
Slide 28
Geodetic inference of rheology
Slide 29
1999 M7.1 Hector Mine earthquake
Slide 30
Freed and Burgmann (2004) Post-earthquake (M7.1 1999 Hector
Mine eq.) Andy Freed (Purdue Univ.)
Slide 31
Post-earthquake (M7.5 1959 Hebgen Lake, Idaho, earthquake)
Nishimura and Thatcher (2003)
Slide 32
Post-lake-filling (1935: Lake Mead, Nevada) Kaufmann and
Amelung (2000) 200 mm subsidence from 1935-1950
Slide 33
Gourmelen and Amelung (2005) Post-earthquake (1915-1954;
Central Nevada Seismic Zone)
Bills et al. (1994) Post-lacustrine unloading (Paleolake
Bonneville, Utah)
Slide 41
James et al. (2000) Post-glacial rebound
Slide 42
Modified from Dixon et al. (2004) Jacqueline DixonTim
Dixon
Slide 43
Goes and van der Lee (2002)
Slide 44
Paradigm shift in Earths continental tectonics, from
Time-independent crustal deformation, punctuated only by crustal
earthquakes and associated localized brittle/plastic deformation,
to Time-dependent crustal deformation, involving deep-seated,
ductile flow and associated broadscale deformation
Slide 45
Rheology of the Lower Crust and Upper Mantle: Evidence from
Rock Mechanics, Geodesy and Field Observations, Annu. Rev. Earth
Planet. Sci. (2008) Roland BurgmannGeorg Dresen
Slide 46
American Geophysical Union 2010 Fall Meeting Linking Geodetic
Observations to Mechanical Properties of the Lithosphere: New
Methods and Models I, II Wayne ThatcherLiz HearnEric HetlandSylvain
BarbotYuri Fialko
Slide 47
SCEC Workshop on Ductile Rheology of the Southern California
Lithosphere (May 1-2, 2013) Wayne ThatcherLiz HearnGreg Hirth