The Manawatu region experiences deep tremor and long-term SSEs; however
tremor is adjacent to, and not co-located with, long-term SSEs.
Observations of Episodic tremor and Slip (ETS) elsewhere suggest it is
possible smaller short-term SSEs below the current detection threshold
occur where tremor is observed. Therefore, we sought to determine if
small SSEs occurred with Manawau tremor. We decomposed GNSS data using
times of tremor to assess average surface displacements and performed a
static slip inversion to model the displacement during tremor. The slip
inversion suggested small slow slip partially coincided with tremor and
long-term SSEs may influence these small SSEs by increasing slip rates.
We suggest that the interface below deep long-term SSEs may slip often,
in small ETS-like SSEs that are not individually detectable
geodetically. The question remains as to the nature of the strong
variability in SSE behavior with depth and duration in the southern