Publication Date:
2013-02-07
Description:
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 ( M 0 ) and completely overlapping source areas. Most of the moderate repeating earthquakes were quasi-periodic with a recurrence interval ( T r ) 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 ( ) and interplate coupling. Apart from spatial variations in , a temporal acceleration in 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 M 0 and T r derived from the San Andreas fault (SAF). The T r – M 0 scaling relationship derived from the SAF can adequately account for the normalized T r 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.
Print ISSN:
0037-1106
Electronic ISSN:
1943-3573
Topics:
Geosciences
,
Physics
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