ESDB200023 20230123200700 Vladimir Kaftan crossref@gcras.ru Geophysical Center of the Russian Academy of Sciences Geophysical Center of the Russian Academy of Sciences Peter Dokukin People's Friendship University of Russia Vladimir Kaftan Geophysical Center RAS Aleksander Manevich Geophysical Center RAS Mining Institute of NUST MISiS Roman Shevchuk Geophysical Center RAS Mining Institute of NUST MISiS Sсhmidt institute of physics of the Earth RAS 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]. 2022 01 2023 Geophysical Center of the Russian Academy of Sciences Moscow, Russia Geophysical Center of the Russian Academy of Sciences Moscow, Russia 10.2205/ESDB-Hikurangi-dilatation 20230123200700 http://esdb.wdcb.ru/doi/2023/esdb-hikurangi-dilatation.html