Quantifying seismicity associated with slow slip events in the Hikurangi margin, New Zealand

To investigate the relationship between seismicity and slow slip events (SSEs) in the Hikurangi margin we calculate seismicity rates during SSEs using the raw GeoNet earthquake catalogue and a derived sequence catalogue from 2002 through 2011. Most regions have more seismicity during SSEs times; the increase is significant for six out of nine regions. Seismicity regionally accompanying SSEs in the Manawatu and Kapiti regions is part of a cluster of normal faulting earthquakes correlated to a convergence-parallel S-Hmax stress direction. Seismicity accompanies the smallest published SSE in 2009, which suggests that the occurrence of seismicity is independent of the total slip. The Manawatu-Kapiti and East Coast regions have, respectively, 1.3 and 1.5 times the average rate of sequences during SSEs. The link between the rate of earthquakes and the timing of SSEs indicates that understanding the connection between the two is important for future hazard analysis and earthquake forecasts.