A low QScS anomaly near the South Pacific superswell

Abstract

We analyzed multiple ScS waves from Tonga-Fiji deep events recorded at the IRIS and SPANET broadband stations to determine lateral variation in attenuation (Q) of the mantle in the South Pacific. We measured average Q values of ScS waves in the mantle between earthquakes and each station, and between two stations. The results of the measurement show that the average Q in the South Pacific is 140. We obtain a very low Q of 70-80 for multiple ScS waves traveling in the South Pacific Superswell, suggesting the existence of higher temperature anomalies in the entire mantle in hot spot regions.