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
The accumulation of vertical displacements and horizontal vectors of internal displacements at permanent points of the New Zealand GNSS network is analyzed. The data of daily determinations of coordinates in the interval 2008/01/01–2021/06/21 were used . The accumulated displacements were calculated, digital and graphical models of their spatial distribution were constructed. Internal displacements were obtained by subtracting the average values of the coordinates for each day from the IGS14 coordinate frame. The resulting images (frames) are combined into a synoptic animation. Tracking the evolution of accumulated displacements in connection with the development of the seismic process made it possible to see the following important features. Up to the first strong seismic event Darfield (September 03, 2010, M 7.1), no anomalous changes in horizontal and vertical motions were detected. But due to a strong aftershock in Pegasus Bay M 6.2, the first significant horizontal displacement of about 20 cm was recorded and an uplift extremum of more than 5 cm was formed. This uplift area expanded over time and reached the position of the epicenters of future strong earthquakes M>6 in the Cook Strait and in the Lake Grassmere area. Simultaneously, there was an increase in horizontal displacement up to 30 cm in the area of Pegasus Bay. The most powerful earthquake of 2016 Kaikoura M 7.8 , close in strength to a mega-earthquake on the qualitative Richter scale, formed a vast uplift in the area of the Kaikoura Triple Junction (KTJ). This elevation is consistent with the area of maximum dilatation deformation . It should be noted that in this case, the maximum coseismic horizontal shift occurred, contrary to expectations, not at the epicenter of the strongest shock, but in the previously fractured zone near the Cook Strait area. The relaxation process continued the growth of horizontal displacement vectors at the continental boundary of the uplift area. The maximum shift of one of the points in the Cook Strait area reached 2.8 m. The pattern of horizontal and vertical displacements can be explained by the underthrusting of the oceanic crust under the island crust in the area of KTJ and the location of the mantle superplume . In this case, it is very important to understand the role of the ascending mantle flow in the pattern of observed movements and deformations of the upper crust. An interesting fact that requires explanation is the eddy character of the horizontal movements of GPS points in the southern part of the North Island of New Zealand.
Database creation date: 2022; Publication date: 23 January 2023
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)
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-movement
- Blewitt, G., Hammond, W. C., Kreemer C. Harnessing the GPS data explosion for interdisciplinary science. Eos, 99 (2018) https://doi.org/10.1029/2018EO104623.
- 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.
- Dokukin P. A., Kaftan V. I., Manevich A. I., Shevchuk R. V. Evolution of the seismic process and horizontal dilatation strain (2008–2021) under the influence of the Hikurangi mantle superplume. ESDB repository, GCRAS, Moscow, 2023 https://doi.org/10.2205/ESDB-Hikurangi-dilatation
- 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: This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
- Hits: 35