The average QES value is consistent with the previous results obtained in some back-arc regions such as Japan Sea and may suggest a similar termination age of spreading process. However, since the distribution of 90 ray paths can be roughly classified into two directions, northeast-southwest (NE-SW) and northwest-southeast (NW-SE), the average Q values of these two directions are derived to be QNE-SW = 455±109 and QNW-SE = 133±50, respectively. |