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

Abstract

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. ARTICLE HISTORY

Earthquakes and Tremor Linked to Seamount Subduction During Shallow Slow Slip at the Hikurangi Margin, New Zealand

“…Clear seismicity increases do not accompany every shallow SSE along the northern Hikurangi Margin, but significant increases have been identified during the largest shallow SSEs such as the 2004 and 2010 Gisborne SSEs, and the 2011 Cape Turnagain SSE (Bartlow et al, ; Delahaye et al, ; Jacobs et al, ; Wallace, Beavan, et al, ). The 2014 Gisborne SSE has a small increase in seismicity starting at the beginning of the geodetically detected slip that continues for several days with the largest increase in seismicity rate occurring toward the end of the slip event.…”

Tectonic tremor along the northern Hikurangi Margin, New Zealand, between 2010 and 2015

“…Due to the geometry of the coastline, most of the slip is farther from land and the GeoNet seismic and cGPS stations than the northern slip patches. The coastal region extending south of Poverty Bay, along the Mahia Peninsula, and the northern edge of Hawke's Bay is also the site of increased microseismicity observed with SSEs in the Gisborne and Mahia patches [e.g., Delahaye et al ., ; Jacobs et al ., ]. Since the methodology employed skips time windows with substantial correlations in the higher frequency band, the increased presence of microseismicity associated with SSEs adds to the existing geographic complexities with automatically detecting tremor in this region.…”

“…Jacobs et al . [] showed that this swarm is the northernmost in a series of three earthquake sequences that migrated northeast along strike from the Mahia Peninsula in 2007, 2009, and 2010. The largest earthquakes in the 2010 swarm consist of normal mechanisms and are likely intraslab events.…”

“…Journal of Geophysical Research: Solid Earth 10.1002/2016JB013480 the northern edge of Hawke's Bay is also the site of increased microseismicity observed with SSEs in the Gisborne and Mahia patches [e.g., Delahaye et al, 2009;Jacobs et al, 2016]. Since the methodology employed skips time windows with substantial correlations in the higher frequency band, the increased presence of microseismicity associated with SSEs adds to the existing geographic complexities with automatically detecting tremor in this region.…”

Introduction toNZJGGspecial issue in honour of John Beavan's scientific contributions

“…A key result is the high sensitivity of the tsunami impact in Cook Strait to how far ruptures extend across the strait. A contribution from Jacobs et al (2016) outlines the relationships between seismicity and slow-slip events (SSEs) in the Hikurangi margin. The authors calculate seismicity rates during SSEs using the raw GeoNet earthquake catalogue and a derived sequence catalogue from 2002 through 2011.…”