scholarly journals The <i>M</i><sub>w</sub> 7.5 Tadine (Maré, Loyalty Islands) earthquake and related tsunami of 5 December 2018: seismotectonic context and numerical modeling

2021 ◽  
Vol 21 (11) ◽  
pp. 3489-3508
Author(s):  
Jean Roger ◽  
Bernard Pelletier ◽  
Maxime Duphil ◽  
Jérôme Lefèvre ◽  
Jérôme Aucan ◽  
...  
Keyword(s):  
Wave Amplitude ◽  
East Coast ◽  
Fault Plane ◽  
New Caledonia ◽  
Integrated System ◽  
Plane Geometry ◽  
Deformation Model ◽  
Tsunami Generation ◽  
Slip Model ◽  
Source Modeling

Abstract. On 5 December 2018, a magnitude Mw 7.5 earthquake occurred southeast of Maré, an island of the Loyalty Islands archipelago, New Caledonia. This earthquake is located at the junction between the plunging Loyalty Ridge and the southern part of the Vanuatu Arc, in a tectonically complex and very active area regularly subjected to strong seismic crises and earthquakes higher than magnitude 7 and up to 8. Widely felt in New Caledonia, it was immediately followed by a tsunami warning, confirmed shortly after by a first wave arrival at the Loyalty Islands tide gauges (Maré and Lifou), and then along the east coast of Grande Terre of New Caledonia and in several islands of the Vanuatu Archipelago. Two solutions of the seafloor initial deformation are considered for tsunami generation modeling, one using a non-uniform finite-source model from USGS and the other being a uniform slip model built from the Global Centroid Moment Tensor (GCMT) solution, with the geological knowledge of the region and empirical laws establishing relationships between the moment magnitude and the fault plane geometry. Both tsunami generation and propagation are simulated using the Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM), an open-source modeling code solving the shallow-water equations on an unstructured grid allowing refinement in many critical areas. The results of numerical simulations are compared to tide gauge records, field observations and testimonials from 2018. Careful inspection of wave amplitude and wave energy maps for the two simulated scenarios shows clearly that the heterogeneous deformation model is inappropriate, while it raises the importance of the fault plane geometry and azimuth for tsunami amplitude and directivity. The arrival times, wave amplitude and polarities obtained with the uniform slip model are globally coherent, especially in far-field locations (Hienghène, Poindimié and Port Vila). Due to interactions between the tsunami waves and the numerous bathymetric structures like the Loyalty and Norfolk ridges in the neighborhood of the source, the tsunami propagating toward the south of Grande Terre and the Isle of Pines is captured by these structures acting like waveguides, allowing it to propagate to the north-northwest, especially in the Loyalty Islands and along the east coast of Grande Terre. A similar observation results from the propagation in the Vanuatu islands, from Aneityum to Efate.

Redescription of Pseudogilquinia pillersi (Southwell, 1929) (Cestoda, Trypanorhyncha) from serranid and lethrinid fishes from New Caledonia and Australia

2007 ◽  
Vol 52 (3) ◽  
Author(s):  
Ian Beveridge ◽  
Claude Chauvet ◽  
Jean-Lou Justine
Keyword(s):  
Sri Lanka ◽  
Host Range ◽  
East Coast ◽  
New Caledonia ◽  
Epinephelus Coioides ◽  
North East ◽  
The North ◽  
Specific Variation ◽  
Epinephelus Malabaricus

AbstractPseudogilquinia pillersi (Southwell, 1929), a poorly known species of trypanorhynch, is redescribed from plerocerci collected from Epinephelus coioides (Hamilton, 1922), Epinephelus malabaricus (Bloch et Schneider, 1801) (Serranidae) and Plectropomus laevis (Lacépède, 1801) (Serranidae) off New Caledonia. These were compared with specimens from Lethrinus atkinsoni Seale, 1910 and Lethrinus miniatus (Forster, 1801) (Lethrinidae) off the north-east coast of Australia as well as syntypes from Protonibea diacantha (Lacépède, 1802) from Sri Lanka. Although size differences were found in parts of the scolex as well as in the sizes of the tentacular hooks, the hook arrangements were identical in all specimens. The differences observed were attributed provisionally to intra-specific variation across a wide geographic and host range.

scholarly journals Fault reactivation by gas injection at an underground gas storage off the east coast of Spain

2019 ◽  
Author(s):  
Antonio Villaseñor ◽  
Robert B. Herrmann ◽  
Beatriz Gaite ◽  
Arantza Ugalde
Keyword(s):  
East Coast ◽  
Fault Plane ◽  
Source Parameters ◽  
Gas Injection ◽  
Focal Depth ◽  
Gas Storage ◽  
Fault Reactivation ◽  
Underground Gas Storage ◽  
Waveform Modeling ◽  
Valencia Trough

Abstract. During September–October of 2013 an intense swarm of earthquakes occurred off the east coast of Spain associated with the injection of the base gas in an offshore underground gas storage. Two weeks after the end of the injection operations, three moderate-sized earthquakes (Mw 4.0–4.1) occurred near the storage. These events were widely felt by the nearby population, leading to the indefinite shut-down of the facility. Here we investigate the source parameters (focal depth and mechanism) of the largest earthquakes in the sequence in order to identify the faults reactivated by the gas injection, and to help understand the processes that caused the earthquakes. Our waveform modeling results indicate that the largest earthquakes occurred at depths of 6–8 km beneath the sea floor, significantly deeper than the injection depth (~ 1800 m). Although we cannot undoubtedly discriminate the fault plane from the two nodal planes of the mechanisms, most evidence seems to favor a NW-SE striking fault plane. We propose that the gas injection reactivated unmapped faults in the Paleozoic basement, with regional orientation possibly inherited from the opening of the Valencia Trough.

scholarly journals Control of fault plane geometry on the formation of a normal fault-related anticline: an experimental approach

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Wei Long ◽  
Zhongquan Li ◽  
Ying Li ◽  
Junliang Chen ◽  
Hongkui Li ◽  
...  
Keyword(s):  
Experimental Approach ◽  
Fault Plane ◽  
Normal Fault ◽  
Plane Geometry

scholarly journals Nonlinear tsunami generation mechanism

2001 ◽  
Vol 1 (4) ◽  
pp. 251-253 ◽  
Author(s):  
M. A. Nosov ◽  
S. N. Skachko
Keyword(s):  
Surface Wave ◽  
Surface Water ◽  
High Frequency ◽  
Water Wave ◽  
Wave Amplitude ◽  
Water Layer ◽  
Generation Mechanism ◽  
Tsunami Generation ◽  
Constant Depth ◽  
Nonlinear Mechanism

Abstract. The nonlinear mechanism of long gravitational surface water wave generation by high-frequency bottom oscillations in a water layer of constant depth is investigated analytically. The connection between the surface wave amplitude and the parameters of bottom oscillations and source length is investigated.

Modelling, Identification and Control of Thermal Deformation of Machine Tool Structures, Part 5: Experimental Verification

1999 ◽  
Vol 121 (3) ◽  
pp. 517-523 ◽  
Author(s):  
S. Fraser ◽  
M. H. Attia ◽  
M. O. M. Osman
Keyword(s):  
Control System ◽  
Machine Tool ◽  
Thermal Deformation ◽  
Transfer Functions ◽  
Integrated System ◽  
Design Stage ◽  
Machining Accuracy ◽  
Deformation Model ◽  
Component Structure ◽  
Artificial Heat

Machining accuracy is more often governed by thermal deformation of the machine tool structure than by static stiffness and dynamic rigidity. Since thermally induced errors cannot completely be eliminated at the design stage, the use of control and compensation systems is an inevitable course of action. Existing control systems are based on two different approaches; the use of empirical compensation function, and on-line execution of numerical simulation models. To overcome the limitations of these methods, a new control system has recently been proposed by the authors. This system, which is based on the concept of generalized modelling, incorporates a realtime inverse heat conduction problem IHCP solver to estimate the transient thermal load applied to the structure. With this information, the relative thermal deformation between the tool and the workpiece is estimated and used as a feedback control signal. In previous parts of this series, computer simulation test cases were carried out to examine the dynamic response, accuracy and stability of the system. In the present study, the performance of various components of the control system, specifically, the IHCP solver, the thermal deformation estimator, and the feedback controller are verified experimentally using a three-component structure. The results showed that the derived generalized thermoelastic transfer functions and algorithms are indeed quite accurate in predicting and controlling the transient thermoelastic response behaviour of a predominantly linear structure. The results showed that the a IHCP solver is inherently stable even when the temperature measurements are contaminated with random errors. The excellent computational efficiency of the integrated system is shown to be well suited for real-time control applications involving multi-dimensional structures, achieving a control cycle of less than 0.5 second. The experimental results showed that in real structures higher modes can be present, and therefore, a fourth order deformation model should be used to improve the prediction accuracy. The proposed PID control system, with feedforward branches, was capable of reducing thermal deformations of the order of 200 μm to levels below ±8 μm. These results also demonstrated the effectiveness of artificial heat sources as a control actuation mechanism, in spite of their inherent limitations, namely, thermal inertia, coupledness, and unidirectionality.

scholarly journals Fault reactivation by gas injection at an underground gas storage off the east coast of Spain

Solid Earth ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 63-74
Author(s):  
Antonio Villaseñor ◽  
Robert B. Herrmann ◽  
Beatriz Gaite ◽  
Arantza Ugalde
Keyword(s):  
East Coast ◽  
Fault Plane ◽  
Source Parameters ◽  
Gas Injection ◽  
Focal Depth ◽  
Gas Storage ◽  
Fault Reactivation ◽  
Underground Gas Storage ◽  
Waveform Modeling ◽  
Valencia Trough

Abstract. During September–October of 2013 an intense swarm of earthquakes occurred off the east coast of Spain associated with the injection of the base gas in an offshore underground gas storage. Two weeks after the end of the injection operations, three moderate-sized earthquakes (Mw 4.0–4.1) occurred near the storage. These events were widely felt by the nearby population, leading to the indefinite shut-down of the facility. Here we investigate the source parameters (focal depth and mechanism) of the largest earthquakes in the sequence in order to identify the faults reactivated by the gas injection and to help understand the processes that caused the earthquakes. Our waveform modeling results indicate that the largest earthquakes occurred at depths of 6–8 km beneath the sea floor, significantly deeper than the injection depth (∼1800 m). Although we cannot undoubtedly discriminate the fault plane from the two nodal planes of the mechanisms, most evidence seems to favor a NW–SE-striking fault plane. We propose that the gas injection reactivated faults in the Paleozoic basement, with regional orientation possibly inherited from the opening of the Valencia Trough.

scholarly journals First assessment of interchange of humpback whales between Oceania and the East coast of Australia

2020 ◽  
pp. 269-274
Author(s):  
Claire Garrigue ◽  
Trish Franklin ◽  
Rochelle Constantine ◽  
Kirsty Russell ◽  
Daniel Burns ◽  
...  
Keyword(s):  
New Zealand ◽  
East Coast ◽  
New Caledonia ◽  
South Pacific ◽  
French Polynesia ◽  
American Samoa ◽  
Individual Identification ◽  
Humpback Whales ◽  
Cook Island ◽  
Breeding Grounds

The interchange of individual humpback whales between the wintering grounds of Oceania (South Pacific) and the east coast of Australia weredocumented by individual identification photographs collected from 1999 to 2004. Interchange was assessed using regional catalogues of flukephotographs, totalling 672 individuals from Oceania (represented by New Zealand, New Caledonia, Vanuatu, Fiji, Samoa, Tonga, Niue, Cook Island,French Polynesia and American Samoa) and 1,242 individuals from Hervey Bay and Byron Bay representing the southbound and the northboundmigration along the east coast of Australia (EA). Overall, there were seven documented movements between EA and Oceania. Four instances ofmovement of four individuals were documented between EA and the closest breeding grounds of New Caledonia. A further three movements wererecorded between EA and a small catalogue (n = 13) from the New Zealand migratory corridor. In contrast, during this same period, 20 cases ofinterchange were documented among nine breeding grounds: French Polynesia, Cook Islands, Niue, American Samoa, Samoa, Tonga, Fiji, Vanuatuand New Caledonia. The low level of interchange between Oceania and the east coast of Australia has important implications for understanding thestock structure and abundance of humpback whales in the South Pacific.

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