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Geoffroy Lamarche

Geoffroy Lamarche
Parliamentary Commissioner for the Environment

PhD

About

168
Publications
66,459
Reads
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4,668
Citations
Additional affiliations
December 2019 - present
Parliamentary Commissioner for the Environment
Position
  • Consultant
June 2017 - October 2021
University of Auckland
Position
  • Professor (Associate)
Description
  • 20% position shared with NIWA from 2017 to 2019, now an Honorarium position.
October 1998 - November 2019
National Institute of Water and Atmospheric Research
Position
  • Principal Investigator

Publications

Publications (168)
Article
Full-text available
We investigated the tsunami hazard in the remote French territory of Wallis and Futuna, Southwest Pacific, using the Gerris flow solver to produce numerical models of tsunami generation, propagation and inundation. Wallis consists of the inhabited volcanic island of Uvéa that is surrounded by a lagoon delimited by a barrier reef. Futuna and the isl...
Technical Report
Full-text available
Executive summary Interest in offshore hydrocarbon and minerals exploration is growing rapidly as investors identify the potential economic returns from New Zealand’s rich marine resources. The challenge for management agencies and scientists is how to facilitate development of this natural resources while ensuring environmental sustainability is n...
Article
Full-text available
With the COVID-19 pandemic came what media has deemed the “port congestion pandemic”. Intensified by the pandemic, the commonplace anchoring of high-tonnage ships causes a substantial geomorphologial footprint on the seabed outside marine ports globally, but isn’t yet quantified. We present the first characterisation of the footprint and extent of...
Article
Full-text available
Understanding fluid expulsion is key to estimating gas exchange volumes between the seafloor, ocean, and atmosphere; for locating key ecosystems; and geohazard modelling. Locating active seafloor fluid expulsion typically requires acoustic backscatter data. Areas of very-high seafloor backscatter, or “hardgrounds,” are often used as first-pass indi...
Article
The distribution of benthic ecosystems, dominated by filter-feeding communities, is highly influenced by the seabed geomorphology. However, the spatial variation in settlement of these species is also affected by near-bottom currents and any changes in light, nutrient concentration and food quality often associated with increases of suspended sedim...
Article
Full-text available
The shallow marine environment represents a region of high biological productivity, ecological diversity, and complex oceanographic conditions, and often supports various human activities and industries. Mapping of the seafloor in shallow marine environments reveals seafloor features in detail, shedding light on a range of natural and anthropogenic...
Technical Report
Full-text available
The intended purpose of this document is to serve as a resource to the seafloor mapping community, as a brief report on the innovative geomorphology mapping and analysis tools demonstrated at the 2019 GeoHab pre-conference workshop, here presented as case-studies. We also summarise workshop discussion points on the demands and applications for seaf...
Article
Full-text available
Hydrogeological processes influence the morphology, mechanical behavior, and evolution of subduction margins. Fluid supply, release, migration, and drainage control fluid pressure and collectively govern the stress state, which varies between accretionary and nonaccretionary systems. We compiled over a decade of published and unpublished acoustic d...
Article
Full-text available
An international research group recorded the acoustic signatures of gas bubbles rising from a hydrothermal vent field to gather clues about greenhouse gases escaping into the atmosphere. https://eos.org/science-updates/gas-bubble-forensics-team-surveils-the-new-zealand-ocean
Article
Full-text available
Detailed knowledge of the shape of the seafloor is crucial to humankind. Bathymetry data is critical for safety of navigation and is used for many other applications. In an era of ongoing environmental degradation worldwide, bathymetry data (and the knowledge derived from it) play a pivotal role in using and managing the world’s oceans in a way tha...
Article
Multiple (>20) crustal faults ruptured to the ground surface and seafloor in the 14 November 2016 Mw 7.8 Kaikōura earthquake, and many have been documented in detail, providing an opportunity to understand the factors controlling multifault ruptures, including the role of the subduction interface. We present a summary of the surface ruptures, as we...
Article
Full-text available
Using automated supervised segmentation of multibeam backscatter data to delineate seafloor substrates is a relatively novel technique. Low-frequency multibeam echosounders (MBES), such as the 12-kHz EM120, present particular difficulties since the signal can penetrate several metres into the seafloor, depending on substrate type. We present a case...
Article
Full-text available
Multibeam echosounders are becoming widespread for the purposes of seafloor bathymetry mapping, but the acquisition and the use of seafloor backscatter measurements, acquired simultaneously with the bathymetric data, are still insufficiently understood, controlled and standardized. This presents an obstacle to well-accepted, standardized analysis a...
Article
Full-text available
With the ability of multibeam echo sounders (MBES) to measure backscatter strength (BS) as a function of true angle of insonification across the seafloor, came a new recognition of the potential of backscatter measurements to remotely characterize the properties of the seafloor. Advances in transducer design, digital electronics, signal processing...
Article
Full-text available
Obtaining absolute seafloor backscatter measurements from hydrographic multibeam echosounders is yet to be achieved. We propose a low-cost experiment to calibrate the various acquisition modes of a 30-kHz Kongsberg EM 302 multibeam echosounder in a range of water depths. We use a 38-kHz Simrad EK60 calibrated fisheries split-beam echosounder mounte...
Article
During the 2016 Mw 7.8 Kaikoura earthquake, the Kekerengu fault ruptured the ground surface and produced a maximum of ∼12 m of net displacement (dextral slip with minor reverse slip), one of the largest five coseismic surface-rupture displacements so far observed globally. This study presents the first combined onshore to offshore dataset of coseis...
Article
Full-text available
Although the global flux of sediment and carbon from land to the coastal ocean is well known, the volume of material that reaches the deep ocean—the ultimate sink—and the mechanisms by which it is transferred are poorly documented. Using a globally unique data set of repeat seafloor measurements and samples, we show that the moment magnitude (Mw) 7...
Article
Full-text available
Despite many of years of mapping effort, only a small fraction of the world ocean’s seafloor has been sampled for depth, greatly limiting our ability to explore and understand critical ocean and seafloor processes. Recognizing this poor state of our knowledge of ocean depths and the critical role such knowledge plays in understanding and maintainin...
Article
Full-text available
Ontong Java and Nukumanu atolls sit atop Earth's largest oceanic plateau – the Ontong Java Plateau – in the western equatorial Pacific Ocean. In 2014, scientists aboard the Schmidt Ocean Institute's RV Falkor mapped the seafloor surrounding Ontong Java Atoll (Solomon Islands) and Nukumanu Atoll (Papua New Guinea) for the first time using multibeam...
Article
Full-text available
The New Zealand region contains untapped natural mineral, oil, and gas resources while also supporting globally unique and diverse faunal communities that need to be managed sustainably. In this paper key information from the international literature is reviewed that can underpin an Environmental Mining Management System which includes elements of...
Article
We provide a summary of the surface fault ruptures produced by the Mw7.8 14 November 2016 Kaikōura earthquake, including examples of damage to engineered structures, transportation networks and farming infrastructure produced by direct fault surface rupture displacement. We also provide an overview of the earthquake in the context of the earthquake...
Article
Full-text available
We provide a summary of the surface fault ruptures produced by the Mw7.8 14 November 2016 Kaikōura earthquake, including examples of damage to engineered structures, transportation networks and farming infrastructure produced by direct fault surface rupture displacement. We also provide an overview of the earthquake in the context of the earthquake...
Technical Report
Full-text available
Interest in offshore hydrocarbon and minerals exploration is growing rapidly as investors identify the potential economic returns from New Zealand’s rich marine resources. The challenge for management agencies is how to facilitate development of these natural resources while ensuring environmental sustainability is not compromised. In 2012 the Mini...
Article
Full-text available
Devastating tsunami over the last decade have significantly heightened awareness of the potential consequences and vulnerability of low-lying Pacific islands and coastal regions. Our appraisal of the potential tsunami hazard for the atolls of the Tokelau Islands is based on a tsunami source-propagation-inundation model using Gerris Flow Solver, ada...
Chapter
Making deep-sea benthic habitat maps requires expensive and complex technologies to acquire, process and interpret remotely sensed data. Recent technologies that have advanced the field significantly include side-scan sonar, multibeam echosounders and autonomous underwater vehicles. Acquisition of bathymetric and backscatter data using these tools...
Chapter
Full-text available
This sixth edition of the Submarine Mass Movements and Their Consequences volume, coincident with the seventh eponymous conference includes 61 papers that span a variety of topics and are organized into nine parts as follows: (1) Submarine mass movement in margin construction and economic significance; (2) Failure dynamics from landslide geomorphol...
Chapter
Full-text available
This sixth edition of the Submarine Mass Movements and Their Consequences volume, coincident with the seventh eponymous conference includes 61 papers that span a variety of topics and are organized into nine parts as follows: (1) Submarine mass movement in margin construction and economic significance; (2) Failure dynamics from landslide geomorphol...
Article
Full-text available
We investigated the tsunami hazard in the remote French territory of Wallis and Futuna, Southwest Pacific, using the Gerris flow solver to produce numerical models of tsunami generation, propagation and inundation. Wallis consists of the inhabited volcanic island of Uvéa that is surrounded by a lagoon delimited by a barrier reef. Futuna and the isl...
Article
Full-text available
Devastating tsunami over the last decade have significantly heightened awareness of the potential consequences and vulnerability to tsunami for low-lying Pacific islands and coastal regions. Our tsunami risk assessment for the atolls of the Tokelau Islands was based on a tsunami source–propagation–inundation model using Gerris Flow Solver, adapted...
Article
Full-text available
Devastating tsunamis over the last decade have significantly heightened an awareness of the potential consequences and vulnerability to tsunami for low-lying Pacific islands and coastal regions. The tsunami inundation assessment was based on a tsunami source-propagation-inundation model using Gerris flow solver adapted in the companion study by Lam...
Article
ResumeLes proprietes magnetiques des schistes, gres et calcaires du flysch eocene de la zone dauphinoise ont ete etudiees en relation avec la mineralogie et la structure de ces roches. La susceptibilite magnetique en champ faible est principalement due au paramagnetisme des phyllosilicates (illite et chlorite).L’anisotropie de susceptibilite corres...
Technical Report
Full-text available
Executive summary New Zealand's marine estate contains large untapped natural mineral, oil, and gas resources that comprise a major source of potential wealth for New Zealand. The area also supports a globally unique and diverse biota that contributes important ecosystem services that need to be protected. The Exclusive Economic Zone and Continenta...
Article
Full texte at http://www.insu.cnrs.fr/node/4691 Abstract: A partir de l’analyse détaillée de glissements de terrains sous-marins (turbidites), une équipe franco-néozélandaise1 vient de reconstituer le calendrier des séismes survenus durant plus de 16 500 ans le long de la marge en subduction Nord Hikurangi, en Nouvelle Zélande. Outre le taux de ré...
Article
Full-text available
Active fault traces are a surface expression of permanent deformation that accommodates the motion within and between adjacent tectonic plates. We present an updated national-scale model for active faulting in New Zealand, summarize the current understanding of fault kinematics in 15 tectonic domains, and undertake some brief kinematic analysis inc...
Conference Paper
Full-text available
The NIWA-led programme, Enabling Management of Offshore Mining through improved understanding of environmental impacts (or EMOM), has three main research aims. One research aim is to develop science guidelines for management of offshore environmental impacts. This includes reviewing the international literature and experiences gained from New Zeala...
Article
Full-text available
This special issue of Natural Hazards and Earth System Sciences (NHESS) contains 16 papers that resulted from the European Science Foundation (ESF) Research Conference "Submarine Paleoseismology: The Offshore Search of Large Holocene Earthquakes" that was held at the Universitatszentrum Obergurgl (Austria), from 11 to 16 September 2010 (Pantosti et...