Evolution of the seismic process and horizontal dilatation strain (2008–2021) under the influence of the Hikurangi mantle superplume
1 People's Friendship University of Russia, Moscow, Russia
2 Geophysical Center RAS, Moscow, Russia
3 Mining Institute of NUST MISiS, Moscow, Russia
4 Sсhmidt institute of physics of the Earth RAS, Moscow, Russia
Abstract
The accumulation of horizontal dilatation strain in the triangles of the New Zealand GNSS network is analyzed. The data of daily determinations of coordinates in the interval 2008/01/01–2021/06/21 [1] were used. The accumulated dilatation strains were calculated and digital and graphical models of their spatial distribution were constructed. The resulting images (frames) are combined into a synoptic animation. Observation of the evolution of the deformation process in connection with the development of seismicity made it possible to see the following important features. It is noteworthy that in the period under study, before the start of the seismic-deformation process, two moderate earthquakes occurred near the Kaikoura Triple Junction (KTJ). At the same time, the accumulation of significant dilatation deformation was not detected, apparently due to a short observation period of about 10 months. In the area of location of the Darfield earthquake (September 03, 2010, M 7.1), no significant dilatation is also observed until its occurrence, which indicates the primacy of shear deformations in this area. More than six months later, the strongest M 6.2 aftershock on the coast of Pegasus Bay served as the beginning of the formation and growth of the main extremum of extensions in the KTJ region. As it became clear later, this extremum underwent intensive development. When the stretch level of 10-5 was reached, two strong earthquakes occurred in the Cook Strait and near Lake Grassmere, forming a series of moderate shocks, after which the stretch zone increased significantly and reached a deformation of 1.5×10-5. The subsequent strongest Kaikoura earthquake (November 14, 2016, M 7.8) and the combination of its aftershocks, often reaching M>6, formed a huge expanding zone up to extraordinary values of 15×10-4 [2]. Over the next six years, the dilatation showed stabilization, indicating the exhaustion of the previously accumulated elastic energy that generates a set of such powerful seismic events. The observed evolution of dilatation deformation links the deformation process with the activity of the Hikuranga superplume and its role in the development of the seismic process [3].
Database creation date: 2022; Publication date: 23 January 2023
Contributor:
Geophysical Center of the Russian Academy of Sciences, Moscow, Russia
Institution: Geophysical Center of the Russian Academy of Sciences, Moscow, Russia
Publisher: Geophysical Center of the Russian Academy of Sciences (GC RAS), Moscow, Russia (http://www.gcras.ru/eng/)
Data format: .mov (QuickTime File Format)
doi: 10.2205/ESDB-Hikurangi-dilatation
Citation: Dokukin P. A., Kaftan V. I., Manevich A. I., Shevchuk R. V. (2023) Evolution of the seismic process and horizontal dilatation strain (2008–2021) under the influence of the Hikurangi mantle superplume. ESDB repository, GCRAS, Moscow, https://doi.org/10.2205/ESDB-Hikurangi-dilatation
References:
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- Shi X., Tapponnier P., Wang T., Wei S., Wang Y., Wang X., Jiao L. Triple junction kinematics accounts for the 2016 Mw 7.8 Kaikoura earthquake rupture complexity. Proceedings of the National Academy of Sciences, 2019, 116 (52), 26367-2637. https://doi.org/10.1073/pnas.1916770116.
- Stern T., Lamb S., Moore J. D. P., Okaya D., Hochmuth K. High mantle seismic P-wave speeds as a signature for gravitational spreading of superplumes. Sci. Adv. 2020; 27 May 2020, Vol. 6, Issue 22, https://doi.org/10.1126/sciadv.aba7118.
License: 
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URL for downloading: http://esdb.wdcb.ru/doi/2023/ESDB-Hikurangi-dilatation/2022_Dokukin_Kaftan_Dilatation.mov
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