Geodetic measurements reveal at least 25-yr-long postseismic displacement following the 1989 class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0012821X15007815&_mathId=si6.gif&_user=111111111&_pii=S0012821X15007815&_rdoc=1&_issn=0012821X&md5=1f85f86de755735a2d9ca2d5627e685a" title="Click to view the MathML source">M_wclass="mathContainer hidden">class="mathCode">$M_w$ 6.9 Loma Prieta earthquake.

Postseismic displacement rates fell from >4 cm/yr in the first year to millimeter-per-year levels since 2000.

Afterslip dominates the early period postseismic deformation (1989–1994).

Viscoelastic relaxation dominates the later period postseismic deformation since 1994.

Viscous upper mantle (class="mathmlsrc">title="View the MathML source" class="mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0012821X15007815&_mathId=si7.gif&_user=111111111&_pii=S0012821X15007815&_rdoc=1&_issn=0012821X&md5=97735fe58addc85bee9f243299c8300a">class="imgLazyJSB inlineImage" height="16" width="163" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S0012821X15007815-si7.gif">class="mathContainer hidden">class="mathCode">$\eta =3\times {10}^{18}\text{–}2\times {10}^{19}\text{Pa}\text{s}$) and lower crust (class="mathmlsrc">title="View the MathML source" class="mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0012821X15007815&_mathId=si8.gif&_user=111111111&_pii=S0012821X15007815&_rdoc=1&_issn=0012821X&md5=6b7d484c843b14e2c4720ad48acf8a29">class="imgLazyJSB inlineImage" height="16" width="104" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S0012821X15007815-si8.gif">class="mathContainer hidden">class="mathCode">$\eta =6\times {10}^{18}\text{Pa}\text{s}$) can best describe the viscoelastic relaxation.