Array-Based Teleseismic Love Wave Tomography

Fundamental mode Love waves from earthquakes can be contaminated by higher modes, which can affect the accuracy of phase velocity measurements. If such contaminations are not well dealt with, models of Earth's interior structures based on Love waves could be significantly biased. In this study, we develop an array-based teleseismic Love wave tomography method that can mitigate higher-mode interference effects and therefore obtain more accurate phase-velocity maps compared to previous studies. By applying our tomography method to synthetic data, we first illustrate the effectiveness of our method in construction phase velocity maps of fundamental Love waves when 30% of Love waves are contaminated by higher modes. In addition, as a case study, we apply our method to field data from the Western United States to construct phase velocity maps at 20-100 s period. By comparing phase velocity maps obtained by our method with those obtained by ambient noise data which do not suffer the interferences of higher modes, we demonstrate our method can obtain Love wave phase velocity maps as accurately as those based on ambient noise data with deviations smaller than 0.5% of the average value of these phase velocity maps, further illustrating the validity of our method in constructing Love wave phase velocity maps. Plain Language SummaryLove waves excited by earthquakes contain different modes, which could interfere with each other, resulting in inaccurate measurements of their propagation speeds. If such interferences are not properly dealt with, the resulting models of Earth's interior structures constructed by Love waves could be significantly biased. In this study, we develop an array-based tomography method, which can circumvent the problem of interferences of Love waves. By applying our method to synthetic and field data, we demonstrate the effectiveness of our method in constructing Love waves phase velocity maps. These maps can be exploited to understand the deformation and evolution of lithosphere and asthenosphere.