Geodynamic evaluation of the pacific tectonic model for chortis block evolution using 3D numerical models of subduction

2021 ◽  
pp. 103604
Author(s):  
Erika Jessenia Moreno ◽  
Marina Manea
Keyword(s):  
Numerical Models ◽  
Tectonic Model ◽  
The Pacific

Supplemental material: Cenozoic to Recent plate configurations in the Pacific Basin: Ridge subduction and slab window magmatism in western North America

2006 ◽  
Author(s):  
J.K. Madsen ◽  
D.J. Thorkelson ◽  
R.M. Friedman ◽  
D.D. Marshall
Keyword(s):  
North America ◽  
Pacific Basin ◽  
Western North America ◽  
File Size ◽  
Tectonic Model ◽  
Ridge Subduction ◽  
The Pacific ◽  
Northwestern North America ◽  
Slab Window

Geosphere, February 2006, v. 2, p. 11-34, doi: 10.1130/GES00020.1. Movie 1 - Tectonic model for the Pacific Basin and northwestern North America from 53 Ma to 39 Ma. The file size is 1.3 MB.

A model for Archean tectonism. Part 2. Numerical models of vertical tectonism in greenstone belts

1980 ◽  
Vol 17 (1) ◽  
pp. 60-71 ◽  
Author(s):  
Jean-Claude Mareschal ◽  
Gordon F. West
Keyword(s):  
Numerical Models ◽  
Volcanic Eruptions ◽  
Crustal Rocks ◽  
Tectonic Model ◽  
Mechanical Evolution ◽  
Accumulated Strain ◽  
Lava Sequence ◽  
Order Of Magnitude ◽  
Greenstone Belts ◽  
Horizontal Temperature Gradients

A tectonic model that attempts to explain common features of Archean geology is investigated. The model supposes the accumulation, by volcanic eruptions, of a thick basaltic pile on a granitoid crust. The thermal blanketing effect of this lava raises the temperature of the granitic crust and eventually softens it enough that gravitational slumping and downfolding of the lava follows.Numerical models of the thermal and mechanical evolution of a granitoid crust covered with a thick lava sequence indicate that such an evolution is possible when reasonable assumptions are made about the temperature dependence of the viscosity in crustal rocks. These models show the lava sinking in relatively narrow regions while wider granite diapirs appear in between. The convection produces strong horizontal temperature gradients that may cause lateral changes in metamoprhic facies. A one order of magnitude drop in accumulated strain occurs between the granite–basalt interface and the center of the granite diaper at a depth of 10–15 km.

Roles of Hydrothermal Circulations on Heat Flow in the Fore-arc, Northeast Japan Subduction Zone, A Numerical Modeling Study.

2021 ◽  
Author(s):  
Dongwoo Han ◽  
Changyeol Lee
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Oceanic Crust ◽  
Numerical Models ◽  
Accretionary Prism ◽  
High Heat ◽  
Pacific Plate ◽  
Model Calculations ◽  
The Pacific ◽  
Japan Subduction Zone

<p>Heat flow in the fore-arc, Northeast Japan shows characteristic highs and lows in the seaward and landward regions of the trench axis, respectively, compared to 50 mW/m<sup>2</sup> that is constrained from the corresponding half-space cooling model (135 Ma). For example, the high average of 70 mW/m<sup>2</sup> at the 150-km seaward region from the trench was observed while the low average of 30 mW/m<sup>2</sup> at the 50-km landward region was. To explain the differences between the constraints and observations of the heat flow, previous studies suggested that the high heat flow in the seaward region results from the reactivated hydrothermal circulations in the oceanic crust of the Pacific plate along the developed fractures by the flexural bending prior to subduction. The low heat flow is thought to result from thermal blanket effect of the accretionary prism that overlies the cooled subducting slab by the hydrothermal circulations. To understand heat transfer in the landward region of the trench, a series of two-dimensional numerical models are constructed by considering hydrothermal circulations in the kinematically thickening accretionary prism that overlies the converging oceanic crust of the Pacific plate where hydrothermal circulations developed prior to subduction. The model calculations demonstrate no meaningful hydrothermal circulations when the reasonable bulk permeability of the accretionary prism(<10<sup>-14</sup>m<sup>2</sup>) is used; the thermal blanket effect significantly hinders the heat transfer, yielding only the heat flow of 10 mW/m<sup>2</sup> in the landward region, much lower than the average of 30 mW/m<sup>2</sup>. This indicates that other mechanisms such as the expelled pore fluid by compaction of the accretionary prism play important roles in the heat transfer across the accretionary prism.</p>

Air-Sea Fluxes following the Unusually Early Ice Retreats in the Arctic

2020 ◽  
Author(s):  
Dongxiao Zhang ◽  
Chidong Zhang ◽  
Jessica Cross ◽  
Calvin Mordy ◽  
Edward Cokelet ◽  
...  
Keyword(s):  
Sea Ice ◽  
Numerical Models ◽  
Green Energy ◽  
Arctic Sea Ice ◽  
Heat Fluxes ◽  
The Arctic ◽  
Energy Fluxes ◽  
The Pacific ◽  
Arctic Sea ◽  
Ice Retreat

<p>The Arctic has been rapidly changing over the last decade, with more frequent unusually early ice retreats in late spring and summer. Vast Arctic areas that were usually covered by sea ice are now exposed to the atmosphere because of earlier ice retreat and later arrival. Assessment of consequential changes in the energy cycle of the Arctic and their potential feedback to the variability of Arctic sea ice and marine ecosystems critically depends on the accuracy of surface flux estimates. In the Pacific sector of the Arctic, earlier ice retreat generally follows the warm Pacific water inflow into the Arctic through the Bering and Chukchi Seas. Due to ice coverage and irregularity of seasonal ice retreats, air-sea flux measurements following the ice retreats has been difficult to plan and execute. A recent technology development is the Unmanned Surface Vehicles (USVs): The long-range USV saildrones are powered by green energy with wind for propulsion and solar energy for instrumentation and vehicle control. NOAA/PMEL and University of Washington scientists have made surface measurements of the ocean and atmosphere in the Pacific Arctic using saildrones for the past several years. In 2019, for the 1<sup>st</sup> time a fleet of six saildrones capable of measuring both turbulent and radiative heat fluxes, wind stress, air-sea CO<sub>2</sub> flux and upper ocean currents was deployed to follow the ice retreat from May to October, with five of the USVs into the Chukchi and Beaufort Seas while one staying in the Bering Sea. These in situ measurements provide rare opportunities of estimating air-sea energy fluxes during a period of rapid reduction in Arctic sea ice in different scenarios: open water after ice melt, free-floating ice bands, and marginal ice zones. In this study, Arctic air-sea heat and momentum fluxes measured by the saildrones are compared to gridded flux products based on satellite data and numerical models to investigate the circumstances under which they agree and differ, and the main sources of their discrepancies. The results will quantify the uncertainty margins in the gridded flux products and provide insights needed to improve their accuracy. We will also discuss the feasibility of using USVs in sustained Arctic observing system to collect benchmark datasets of the changing surface energy fluxes due to rapid sea ice reduction and provide real time data for improved weather and ocean forecasts.  </p>

scholarly journals Assessment of groundwater resources: Nauru project 2010 – 2019

2019 ◽  
Author(s):  
Luca Alberti ◽  
Ivana La Licata ◽  
Louis Bouchet
Keyword(s):  
Climate Changes ◽  
Numerical Models ◽  
Groundwater Resources ◽  
Small Islands ◽  
Groundwater Extraction ◽  
Fresh Groundwater ◽  
Groundwater Exploitation ◽  
The Pacific ◽  
Freshwater Resource

Nauru is a small limestone island in the Pacific region where, as in many small islands in the world, the population heavilyrely upon groundwater as primary freshwater resource, in conjunction with rainwater and desalinated water.The Nauru project started in 2010 and led by Politecnico di Milano (http://nauru.como.polimi.it/), consisted on the hydrogeological characterization of the northern part of the island and the implementation of 3 numerical models for: (1) understanding the mechanisms governing groundwater flow and accumulation, (2) assess the adequate sustainable fresh groundwater exploitation in order to prevent saltwater upconing occurrences in the area more suitable for groundwater extraction and (3) to simulate future scenarios based on climate changes and population growth.

scholarly journals Structure of the Pacific Walker Circulation Depicted by the Reanalysis and CMIP6

Atmosphere ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1219
Author(s):  
Emmanuel Olaoluwa Eresanya ◽  
Yuping Guan
Keyword(s):  
Large Scale ◽  
Structural Changes ◽  
Numerical Models ◽  
Walker Circulation ◽  
Future Climate Change ◽  
Western Boundary ◽  
Extreme Caution ◽  
The Pacific ◽  
Mean State

The Pacific Walker circulation (PWC) is one of the most important components of large-scale tropical atmospheric circulations. The PWC and its influences have been studied extensively by numerical models and reanalysis. The newly released ERA5 and NCEP2 are the most widely used reanalysis datasets and serve as benchmarks for evaluation of model simulations. If the results of these datasets differ significantly, this could lead to a bias in projected long-term climate knowledge. For better understanding of future climate change, it is necessary to evaluate PWC reanalysis productions. As a result, we compared the PWC structures between the ERA5 and NCEP2 datasets from month to seasonal time scales. We used the zonal mass streamfunction (ZMS) over the equatorial Pacific to indicate the strength of the PWC. The PWC’s average monthly or seasonal cycle peaks around July. From February to June, the NCEP2 shows a higher PWC intensity, whereas the ERA5 shows greater intensity from July to December. The circulation center in the NCEP2 is generally stronger and wider than in the ERA5. The ERA5, however, revealed that the PWC’s west edge (zero line of ZMS over the western Pacific) had moved 10 degrees westward in comparison to the NCEP2. In addition, we compared the PWC mean state in the reanalysis and CMIP6 models; the mean state vertical structures of the tropical PWC in the CMIP6 multi-model ensemble (MME) are similar to those of the reanalyses in structure but weaker and wider than in the two reanalysis datasets. The PWC is broader in CMIP6, and the western boundary is 7 and 17 degrees farther west than in the ERA5 and NCEP2, respectively. This study suggests that, when using reanalysis datasets to evaluate PWC structural changes in intensity and western edge, extreme caution should be exercised.

scholarly journals Black-body luminance and magnitudes per square arcsecond in the Johnson-Cousins BVR photometric bands

2019 ◽  
Vol 11 (3) ◽  
pp. 63 ◽  
Author(s):  
Salvador Bara
Keyword(s):  
Near Infrared ◽  
Numerical Models ◽  
Black Body ◽  
Spectral Energy ◽  
Practical Applications ◽  
Astronomical Society ◽  
V Band ◽  
Intangible Heritage ◽  
Astrophysical Journal ◽  
The Pacific

A relevant amount of light pollution studies deal with the unwanted visual effects of artificial light at night, including the anthropogenic luminance of the sky that hinders the observation of the celestial bodies which are a main target of ground-based astrophysical research, and a key asset of the intangible heritage of humankind. Most quantitative measurements and numerical models, however, evaluate the anthropogenic sky radiance in any of the standard Johnson-Cousins UBVRI photometric bands, generally in the V one. Since the Johnson-Cousins V band is not identical with the visual CIE V() used to assess luminance, the conversion between these two photometric systems turns out to be spectrum-dependent. Given its interest for practical applications, in this Letter we provide the framework to perform this conversion and the transformation constants for black-body spectra of different absolute temperatures. Full Text: PDF ReferencesF. Falchi et al. "The new world atlas of artificial night sky brightness", Sci. Adv. 2, e1600377 (2016). CrossRef M. Kocifaj, "A review of the theoretical and numerical approaches to modeling skyglow: Iterative approach to RTE, MSOS, and two-stream approximation", Journal of Quantitative Spectroscopy & Radiative Transfer 181, 2 (2016). CrossRef M.S. Bessel, "UBVRI PASSBANDS", Publications of the Astronomical Society of the Pacific, 102, 1181 (1990).. CrossRef CIE, Commision Internationale de l'Éclairage. CIE 1988 2° SpectralLuminous Efficiency Function for Photopic Vision. (Vienna, Bureau Central de la CIE, 1990) DirectLink S. Bará, "Variations on a classical theme: On the formal relationship between magnitudes per square arcsecond and luminance", International Journal of Sustainable Lighting IJSL 19(2), 104 (2017). CrossRef A. Sánchez de Miguel, M. Aubé, J. Zamorano, M. Kocifaj, J. Roby, C. Tapia. "Sky Quality Meter measurements in a colour-changing world", Monthly Notices of the Royal Astronomical Society 467(3), 2966 (2017). CrossRef M.S. Bessell, "Standard Photometric Systems", Annual Reviews of Astronomy and Astrophysics, 43, 293 (2005). CrossRef J.B. Oke, "Absolute Spectral Energy Distributions for White Dwarfs", The Astrophysical Journal Suppl. Series 236(27), 21 (1974). CrossRef J.B. Oke, J.E. Gunn, "Secondary standard stars for absolute spectrophotometry", The Astrophysical Journal 266, 713 (1983). CrossRef M.R. Blanton, S. Roweis S., "K-Corrections and Filter Transformations in the Ultraviolet, Optical, and Near-Infrared", The Astronomical Journal, 133(2), 734(2007). Table 1. CrossRef

scholarly journals Applicability of Calculation Formulae of Impact Force by Tsunami Driftage

2021 ◽  
Vol 9 (5) ◽  
pp. 493
Author(s):  
Yoshimichi Yamamoto ◽  
Yuji Kozono ◽  
Erick Mas ◽  
Fumiya Murase ◽  
Yoichi Nishioka ◽  
...  
Keyword(s):  
Large Scale ◽  
Impact Force ◽  
Numerical Models ◽  
Indian Ocean Tsunami ◽  
Tsunami Waves ◽  
Secondary Damage ◽  
The Pacific ◽  
American Society ◽  
The Impact ◽  
Civil Engineers

The aftermath of the Indian Ocean tsunami on 26 December 2004 triggered by the off Sumatra earthquake (magnitude “M” = 9.1), and the Great East Japan earthquake of 11 March 2011 off the Pacific coast of Tohoku (M = 9.0), evidence the secondary damage from driftage collision due to large tsunami waves. To prevent this type of damage, the establishment of methods for predicting driftage movement and calculating the impact force by driftage is necessary. Several numerical models have been developed to predict the driftage movement of objects. Every year, these improve in accuracy and usability. In contrast, there are many calculation formulae for calculating the impact force. However, since there are considerable differences between values calculated using these formulae, the reliability of each formula is unknown. Therefore, in this research, one team of the committee on tsunami research of the Japan Society of Civil Engineers summarizes the main calculation formulae of impact forces that have been proposed until 2019. In addition, for each type of driftage (driftwood, containers, cars, ships), we compare calculation values of these formulae with measured data of large-scale experiments. Finally, we check the range of calculation values for each formula up to 15 m/s in collision velocity and clarify then the following facts: (1) In the case of driftwood, the formulae of Matsutomi, Federal Emergency Management Agency (FEMA) and National Oceanic and Atmospheric Administration (NOAA), and American Society of Civil Engineers (ASCE) are most reliable; (2) In the case of containers, the formulae of Matsutomi, Arikawa et al., FEMA and NOAA, Ikeno et al., and ASCE are most reliable; (3) In the case of cars, the formulae of FEMA and NOAA, and ASCE are most reliable; (4) In the case of ships, the formulae of Mizutani, FEMA and NOAA, and ASCE are most reliable.

scholarly journals Reconstructing geographical boundary conditions for palaeoclimate modelling during the Cenozoic

2016 ◽  
Vol 12 (8) ◽  
pp. 1635-1644 ◽  
Author(s):  
Michiel Baatsen ◽  
Douwe J. J. van Hinsbergen ◽  
Anna S. von der Heydt ◽  
Henk A. Dijkstra ◽  
Appy Sluijs ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Numerical Models ◽  
Specific Treatment ◽  
Deep Ocean ◽  
Time Frame ◽  
Late Eocene ◽  
Plate Tectonic ◽  
Model Simulations ◽  
Tectonic Model ◽  
Continental Shelves

Abstract. Studies on the palaeoclimate and palaeoceanography using numerical model simulations may be considerably dependent on the implemented geographical reconstruction. Because building the palaeogeographic datasets for these models is often a time-consuming and elaborate exercise, palaeoclimate models frequently use reconstructions in which the latest state-of-the-art plate tectonic reconstructions, palaeotopography and -bathymetry, or vegetation have not yet been incorporated. In this paper, we therefore provide a new method to efficiently generate a global geographical reconstruction for the middle-late Eocene. The generalised procedure is also reusable to create reconstructions for other time slices within the Cenozoic, suitable for palaeoclimate modelling. We use a plate-tectonic model to make global masks containing the distribution of land, continental shelves, shallow basins and deep ocean. The use of depth-age relationships for oceanic crust together with adjusted present-day topography gives a first estimate of the global geography at a chosen time frame. This estimate subsequently needs manual editing of areas where existing geological data indicate that the altimetry has changed significantly over time. Certain generic changes (e.g. lowering mountain ranges) can be made relatively easily by defining a set of masks while other features may require a more specific treatment. Since the discussion regarding many of these regions is still ongoing, it is crucial to make it easy for changes to be incorporated without having to redo the entire procedure. In this manner, a complete reconstruction can be made that suffices as a boundary condition for numerical models with a limited effort. This facilitates the interaction between experts in geology and palaeoclimate modelling, keeping reconstructions up to date and improving the consistency between different studies. Moreover, it facilitates model inter-comparison studies and sensitivity tests regarding certain geographical features as newly generated boundary conditions can more easily be incorporated in different model simulations. The workflow is presented covering a middle-late Eocene reconstruction (38 Ma), using a MatLab script and a complete set of source files that are provided in the supplementary material.

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