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It is called "antipodal focusing". See for example Antipodal focusing of seismic waves observed with the USArray. We present an analysis of the M-w = 5.3 earthquake that occurred in the Southeast Indian Ridge on 2010 February 11 using USArray data. The epicentre of this event is antipodal to the USArray, providing us with an opportunity to observe in ...


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Ocean waves (and also in mediterranean type seas and larger lakes, but on a smaller scale) are generated by two processes: locally generated waves ("wind waves"), which follow the direction of the wind; waves generated further out in the sea (i.e. "swell waves"), which do not necessarily follow the direction of the wind. During the night, you are probably ...


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You need to use the following line in your model setup: COORDINATES SPHERICAL Otherwise SWAN will try to calculate wave properties on a curvilinear grid with coordinates provided in meters. In your present case, the computational area is 0.47 m x 0.24 m instead of degrees longitude and latitude.


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The article can be found here in Geophysical Research Letters: Fan, W., McGuire, J. J., Groot‐Hedlin, C. D., Hedlin, M. A. H., Coats, S., & Fiedler, J. W. ( 2019). Stormquakes Geophysical Research Letters, 46. https://doi.org/10.1029/2019GL084217 Abstract Seismic signals from ocean‐solid Earth interactions are ubiquitously recorded on our planet....


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tldr; Increased density corresponds with decreased P-wave velocity The P-wave velocity for an isotropic medium is: $$ V_p = \sqrt\frac{K+4/3\mu}{\rho} $$ where $K$ is the Bulk Modulus, $\mu$ is the shear modulus, and $\rho$ is the density (https://en.wikipedia.org/wiki/Elastic_modulus, see $M$ the P-wave modulus). Isotropy just means that the strain on ...


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Wind blows from sea to land in day and land to sea in night due to pressure and temperature difference. Not so much. This is common in the Mediterranean in summer, for example, where the area sits under a stable area of high pressure and there is little wind caused by the weather system. Go to the Med in winter though, and you'll find the weather systems ...


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I'm making my comment an answer. Waves are ubiquitous, except on land ;-). Waves in the open sea are a mix — a superposition — of waves in different directions.1 The dominating direction of large waves is, after a while, the wind direction; but that's not absolute. You have some omnidirectional background "noise" of chaotic movement as well as ...


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The following sources helped me understand these landforms - hopefully they can help you too :) From the Miranda Shorebird Centre: The Miranda-Kaiaua cheniers are first formed as sand and cockle-shell bars on the foreshore or intertidal flats. The bars are then moved landward by wave action. Eventually the bars attain sufficient height to withstand such ...


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You can retrieve that information from ERA5 reanalisys data. It cover the whole world from 1979 until almost the present. The resolution is 0.25°x0.25° and includes many fields that characterize ocean waves. here is a list of available fields for download in the "Ocean Waves" section: And there is of course, winds data as well.


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I don't know if I fully grasp your question; but I can confirm that slowness and velocity vectors are kind of weird things :-) Let me describe a simple example (and not worry too much about the mathematical details). If in the figure above, if you point your wave not diagonally but just straight down, what happens? Well, $dx$ becomes infinitely large when ...


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I have no experience with SBP-SAT methods, but you may try and go through the references in (and potentially contact the authors of) this paper https://arxiv.org/pdf/1802.06123.pdf . Personally, I don't see a strict need for using such 'complicated' modelling methods for RTM. In the ideal case, you have deghosted (i.e., upgoing) recorded data and a smooth ...


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It is impossible to to convert one recorded time-series into structural information. As you correctly note, the equation $$ v_i = \frac{z_i}{t_i}, \tag{1a}$$ or $$ t_i(z,v) = \frac{z_i}{v_i}, \tag{1b}$$ is difficult to solve when you only a know one time $t_i$. That is, choosing $z_i$ to twice its value would provide twice $v_i$! If you only record time $t$, ...


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This is conceptually relatively simple if you look at where the reflection (and refraction) happen, and in fact you have articulated the key concept in your question: The reflected wave ...Over time it becomes more horizontal and therefore more like a direct wave which takes a shorter and quicker path across the surface. This is absolutely correct. So ...


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So, I know this question was asked a long time ago. But in the spirit of Stack Exchange, I will post my answer for future users perhaps. The Greens functions (i.e., analytical solutions) The first thing to be aware of are the various solutions to the wave equations change for the (1) source type and (2) the dimension. The source type Assuming acoustic ...


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