@article {iwasaki_continuous_2022,
	title = {Continuous Tremor Activity With Stable Polarization Direction Following the 2014 Large Slow Slip Event in the Hikurangi Subduction Margin Offshore New Zealand},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {127},
	number = {2},
	year = {2022},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2021JB022161},
	month = {11/2021},
	pages = {e2021JB022161},
	abstract = {Many types of slow earthquakes have been discovered at subduction zones around the world. However, the physical process of these slow earthquakes is not well understood. To monitor offshore slow earthquakes, a marine seismic and geodetic experiment was conducted at the Hikurangi subduction margin from May 2014 to June 2015. During this experiment, a large slow slip event (Mw 6.8) occurred directly beneath the ocean bottom seismometer (OBS) network. In this study, S-wave splitting and polarization analysis methods, which have been previously used on onshore data to investigate tremor and anisotropy, are applied to continuous OBS waveform data to identify tremors that are too small to detect by the envelope cross correlation method. Continuous tremor activity with stable polarization directions is detected at the end of the 2014 slow slip event and continued for about 2 weeks. The tremors are generated around a southwest bend in the slow slip contours and at the landward edge of a subducted seamount. Our findings corroborate a previous interpretation, based on burst-type repeating earthquakes and intermittent tremor, that localized slow slip and tremor around the seamount was triggered by fluid migration following the large plate boundary slow slip event and indicate tremor occurred continuously rather than as isolated and sporadic individual events.},
	keywords = {New Zealand, polarization, S-wave splitting, Seamount, slow slip, tremor},
	issn = {2169-9356},
	doi = {10.1029/2021JB022161},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021JB022161},
	author = {Iwasaki, Yuriko and Mochizuki, Kimihiro and Ishise, Motoko and Todd, Erin K. and Schwartz, Susan Y. and Zal, Hubert and Savage, Martha K. and Henrys, Stuart and Sheehan, Anne F. and Ito, Yoshihiro and Wallace, Laura M. and Webb, Spahr C. and Yamada, Tomoaki and Shinohara, Masanao}
}
@article {yarce_seismicity_2019,
	title = {Seismicity at the Northern Hikurangi Margin, New Zealand, and Investigation of the Potential Spatial and Temporal Relationships With a Shallow Slow Slip Event},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {124},
	number = {5},
	year = {2019},
	note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2018JB017211},
	pages = {4751{\textendash}4766},
	abstract = {In 2014{\textendash}2015, the Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip experiment deployed seafloor absolute pressure gauges and ocean bottom seismometers directly above a large slow slip event, allowing examination of the relationship between slow slip and earthquakes in detail. Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip data were combined with nearby existing land stations to create a catalog of microseismicity consisting of 2,300 earthquakes ranging in magnitude between 0.5 and 4.7 that is complete to magnitude 1.5, yielding almost twice as many events as detected by the onshore networks alone. This greatly improves the seismicity catalog for this active subduction zone margin, especially in the offshore portion that was difficult to study using only the inland permanent seismic network. The new locations for the events within the footprint of the offshore network show that earthquakes near the trench are systematically shallower than and NW (landward) of their locations using only land-based stations. Our results indicate that Hikurangi seismicity is concentrated in two NE-SW bands, one offshore beneath the outer forearc wedge, one onshore beneath the eastern Raukumara Peninsula, and the majority of earthquakes are within the subducting Pacific plate with a smaller percent at the plate interface. We find a 20-km wide northeast trending gap in microseismicity between the two bands and beneath the inner forearc wedge and this gap in seismicity borders the downdip edge of a slow slip patch.},
	keywords = {gap, Hikurangi, ocean bottom seismometers, seismicity, slow slip},
	issn = {2169-9356},
	doi = {10.1029/2018JB017211},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018JB017211},
	author = {Yarce, J. and Sheehan, A. F. and Nakai, J. S. and Schwartz, S. Y. and Mochizuki, K. and Savage, M. K. and Wallace, L. M. and Henrys, S. A. and Webb, S. C. and Ito, Y. and Abercrombie, R. E. and Fry, B. and Shaddox, H. and Todd, E. K.}
}
@article {todd_earthquakes_2018,
	title = {Earthquakes and Tremor Linked to Seamount Subduction During Shallow Slow Slip at the Hikurangi Margin, New Zealand},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {123},
	number = {8},
	year = {2018},
	note = {_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2018JB016136},
	pages = {6769{\textendash}6783},
	abstract = {Shallow slow slip events have been well documented offshore Gisborne at the northern Hikurangi subduction margin, New Zealand, and are associated with tectonic tremor downdip of the slow slip patch and increases in local microseismicity. Tremor and seismicity on the shallow subduction interface are often poorly resolved due to their distance from land-based seismic and geodetic networks. To address this shortcoming, the Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip experiment deployed 24 absolute pressure gauges and 15 ocean bottom seismometers on the seafloor above the Gisborne slow slip patch to investigate the spatial and temporal extent of slow slip and associated tremor and earthquake activity. We present a detailed spatiotemporal analysis of the seismic signatures of various interplate slip processes associated with the September/October 2014 Gisborne slow slip event. Tectonic tremor begins toward the end and continues after the geodetically constrained slow slip event and is localized in the vicinity of two subducted seamounts within and updip of the slow slip patch. The subsequent, rather than synchronous occurrence of tremor suggests that tremor may be triggered by stress changes induced by slow slip. However, Coulomb failure stress change models based on the slow slip distribution fail to predict the location of tremor, suggesting that seamount subduction plays a dominant role in the stress state of the shallow megathrust. This and the observed interplay of seismic and aseismic interplate slip processes imply that stress changes from slow slip play a secondary role in the distribution of associated microseismicity.},
	keywords = {earthquake, New Zealand, Seamount, slow slip, subduction, tremor},
	issn = {2169-9356},
	doi = {10.1029/2018JB016136},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018JB016136},
	author = {Todd, Erin K. and Schwartz, Susan Y. and Mochizuki, Kimihiro and Wallace, Laura M. and Sheehan, Anne F. and Webb, Spahr C. and Williams, Charles A. and Nakai, Jenny and Yarce, Jefferson and Fry, Bill and Henrys, Stuart and Ito, Yoshihiro}
}
