Modeling the large runup along a narrow segment of the Kaikoura coast, New Zealand following the November 2016 tsunami from a potential landslide

Significance 

In November 2016 an earthquake of magnitude 7.8 (Mw) hit the South Island of New Zealand. Consequently, it triggered tsunamis with maximum runups of up to 7m, that were witnessed along a narrow segment of the coast close to Kaikoura. Literature has it that ruptures occurred on multiple faults triggering the resulting earth movements. Nonetheless, to date, the debate about the source of the earthquake and the characteristics of the resulting tsunami continues. In fact, researchers have labeled this quake as the “most complex earthquake ever studied”. A complex sequence of ruptures occurred with the hypocentre (the point where the ruptures started) being at a depth of 15 kilometers. In preceding studies, several models have been proposed but none of them has been able to reproduce the large concentrated runup of ∼7 m. To generate the large tsunami peak, such as the one observed in Kaikoura tide gauge record and the observed runup height, offshore seafloor movement is necessary, but the offshore extension of the plate-interface rupture and its type, either seismic rupture or a landslide, is uncertain. In addition, dual source earthquake and submarine landslide tsunamis are a poorly understood hazard, because there are too few well-studied examples.

In a recent publication, a team of scientists, Dr. Mohammad Heidarzadeh from the Brunel University London, Dr. David R. Tappin at the University College London, and Dr. Takeo Ishibe from the Association for the Development of Earthquake Prediction in Japan, presented a study where they carried out a thorough and expert review of the source models for the 2016 Kaikoura tsunami. In particular, they focused on developing numerical models for an additional submarine landslide with the potential to successfully reproduce the near-field observed runup of 7m. As such, they proposed a submarine landslide in addition to the earthquake source. Their work is currently published in the research journal, Ocean Engineering.

Briefly, they proposed submarine landslide was delayed 10–20 minutes after the earthquake rupture as opposed to the offshore plate-interface rupture model. In addition, the location of the submarine landslide source was determined based on the iterative numerical tsunami modeling of various scenarios of dual earthquake-landslide sources.

The authors observed that, notwithstanding the uncertainty over an offshore plate-interface rupture and its location, the proposed submarine landslide offered a viable alternative in comparison to previous models. Moreover, it was established that the proposed model was consistent with tsunami waveforms and field runup data. In fact, the dual source was validated using the obtained data while as the landslide component was seen not produce significant seismic signature on the seismic network.

In summary, in order to explain the large and concentrated runup height of 7m witnessed during the 2016 tsunami, a dual, submarine landslide-earthquake mechanism was proposed by Dr. Mohammad Heidarzadeh and his colleagues as an alternative to previously-proposed offshore plate-interface rupture. The presented model comprised of the earthquake source and a theoretical landslide source located offshore Kaikoura. Altogether, the study highlighted the importance of considering observed runup data for earthquake/tsunami source studies through runup inversions. So far, the dual source model presented for the 2016 Kaikoura tsunami is the only source model that reproduces both tide gauge records and the observed near-field runup heights.

Modeling the large runup along a narrow segment of the Kaikoura coast, New Zealand following the November 2016 tsunami from a potential landslide - Advances in Engineering Modeling the large runup along a narrow segment of the Kaikoura coast, New Zealand following the November 2016 tsunami from a potential landslide - Advances in Engineering

About the author

Dr Mohammad Heidarzadeh is an Assistant Professor of Civil Engineering specializing in Coastal Engineering at the Department of Civil & Environmental Engineering of the Brunel University London (UK). He is an international scientist/engineer on large earthquakes, tsunamis and storms and is a well-known expert on Global-Challenge Researches on extreme geo-environmental hazards worldwide. Dr Heidarzaeh is the PI (Principal Investigator) of the £495K GCRF (Global Challenge Research Fund) projct with Indonesia on earthquakes and tsunamis, a Co-I of another £172K GCRF project with India on tsunamis, and a Co-I of a £51K projct with Dominica (Caribbean Sea) on storms.

Dr Heidarzadeh’s main research areas are: Coastal Engineering, Tsunami, Earthquake, Landslide and Storm surge. Dr. Heidarzadeh received his BSc, MSc and PhD, all in Civil Engineering in 2002, 2004 and 2009, respectively. His PhD major was Coastal Engineering with a PhD disseration on the analysis of earthquake and tsunami hazards on coastal infrastructures. His major research interest is interactions of coastal structures and communities with extreme coastal geo-environmental hazards such as tsunamis, storm surges, earthquakes and landslides. Over the past 15 years, Dr Heidarzadeh has contributed to the understanding and analysis of numerous extreme coastal disasters worldwide; especially in Indonesia, Philippines, Oman, Japan, the Caribbean Sea, Ecuador, Mexico, the Mediterranean Sea, Turkey, Iran, Greece, Paopua New Guinea and Solomon Islands. He has published 56 peer-reviewed journal articles in world’s most prestigous jouirnals (Ocean Eng, GRL, GJI, BSSA, Coastal Eng J, PAGEOPH, Nat Hazards, Int J Civil Eng) along with 170 conference presentations. He is the reciepient of several international awards and fellowships and was elected as a member of the International Tsunami Comittee (ITC) affiliated to IUGG in 2015. Dr Heidarzadeh is a fellow of the Japan Society for the Promotion of Science in Japan, the Alexander von Humboldt Foundation in Germany, the Intergovernmental Oceanographic Commission of the UNESCO (UN), the Partnership for Observation of the Global Ocean (POGO) in UK and a fellow of the European Comission.

Dr Heidarzadeh has extensive engineering experiences and was involved in the design and construction of a number of world-class mega infrastructures while working as a senior consulting engineer with Mahab International Consulting Engineering Company (Iran) and the Port and Airport Research Institute (Japan). These projects include extension of Coastal Seawalls, Mega-Embankment Dams and Reservoirs, Underground Tunnels and Metro Infrastructures. Involvement in such mega-infrastructures has given Dr Heidarzadeh the capability of understanding the complexitis of infrastructures development projects and the associated complicated engineering problems. Some of these complex problems faced during these engineering projects have been outlined in his international peer-reviewed journal articles.

Dr Heidarzadeh is an outstanding engineering lecturer through his constructivist teaching philosophy which combines theory and practice in his teaching of engineering materials. His engineering lectures are well supported by his tremendous engineering practical experience which attracted many students in Brunel University and beyond. Dr Heidarzadeh has achieved the highest teaching qualifications in the United Kingdom and is a Fellow of the Higher Education Academi (FHEA) in the UK.

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Reference

Mohammad Heidarzadeh, David R. Tappin, Takeo Ishibe. Modeling the large runup along a narrow segment of the Kaikoura coast, New Zealand following the November 2016 tsunami from a potential landslide. Ocean Engineering, volume 175 (2019) page 113–121.

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