Abstract

This paper examines moderate shallow‐focus repeating earthquakes along the Tonga–Kermadec–Vanuatu subduction zones by cross‐correlating teleseismically recorded waveforms. A total of 23 clusters and 31 doublets are identified with an average cross‐correlation coefficient of >0.8. A master‐event algorithm is used to determine the precise relative locations. I then estimate and superpose the source areas among these event pairs. This analysis reveals that most of these correlated pairs are repeating earthquakes, which have similar seismic moments (M0) and completely overlapping source areas. Most of the moderate repeating earthquakes were quasi‐periodic with a recurrence interval (Tr) on the order of years, and occurred at the plate interface. The repeating earthquakes are used to study spatial–temporal variations in fault‐slip rate (forumla) and interplate coupling. Apart from spatial variations in forumla, a temporal acceleration in forumla is observed, associated with large interplate earthquakes in the Vanuatu region. Interplate coupling is weak for most of the study areas, except the northern section 15°–19° S of the Tonga arc. Strong coupling in the northern Tonga interplate region appears to be at odds with the decoupling expected of a region associated with active back‐arc extension. Repeating earthquakes are also used to examine the scaling relationship between M0 and Tr derived from the San Andreas fault (SAF). The TrM0 scaling relationship derived from the SAF can adequately account for the normalized Tr for the Kermadec, Vanuatu, and Tonga interplate regions where it is decoupled, suggesting that the convergence rate is the predominant influence on the recurrence interval in a repeating earthquake sequence.

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