IMPORTANCE OF ANELASTICITY IN THE INTERPRETATION OF SEISMIC TOMOGRAPHY

Temperature dependence of seismic wave velocities comes both from anha rmonicity and anelasticity. The contribution from anelasticity is show n to be important in the Earth's mantle particularly for shear waves. In the low Q (Q(mu) approximately 100) regions in the upper mantle, th e correction due to anelasticity will roughly double the temperature d erivatives due to anharmonicity alone. The correction for anelasticity will also be important in the deep mantle where Q is larger, if tempe rature derivatives due to anharmonicity will decrease significantly wi th pressure. These results imply that the temperature anomalies associ ated with low velocity anomalies in the mantle will be significantly s maller than previously considered on the basis of anharmonic effect al one and that the amplitude of velocity anomalies will be significantly larger for shear waves than for compressional waves.