Arrow styles in Cartesian coordinate system 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 PS=plot.ps PDF=plot.pdf R=0/10/0/10 J=X10i/7i gmt psbasemap -R$R -J$J -K -Bx1f0.1 -By1f0.1 -BWSen > $PS echo "1 1 0 2i" | gmt psxy -R -J -K -O -Sv1c+b >> $PS echo "1 2 0 2i" | gmt psxy -R -J -K -O -Sv1c+e >> $PS echo "1 3 0 2i" | gmt psxy -R -J -K -O -Sv1c+b+e >> $PS echo "1 4 0 2i" | gmt psxy -R -J -K -O -Sv1c+b+h1 >> $PS echo "1 5 0 2i" | gmt psxy -R -J -K -O -Sv1c+e+h1 >> $PS echo "1 5 0 2i" | gmt psxy -R -J -K -O -Sv1c+e+h1 -Gred >> $PS echo "1 6 0 2i" | gmt psxy -R -J -K -O -Sv1c+m -Gred >> $PS echo "1 7 0 2i" | gmt psxy -R -J -K -O -Sv1c+e+l -Gred >> $PS echo "1 8 0 2i" | gmt psxy -R -J -K -O -Sv1c+e+r -Gred >> $PS echo "1 9 0 2i" | gmt psxy -R -J -K -O -Sv1c+e+a90 -Gred >> $PS echo "5 1 0 2i" | gmt psxy -R -J -K -O -Sv1c+e+h-2 -Gred >> $PS echo "5 2 0 2i" | gmt psxy -R -J -K -O -Sv1c+e+h-1 -Gred >> $PS echo "5 3 0 2i" | gmt psxy -R -J -K -O -Sv1c+e+h2 -Gred >> $PS echo "5 4 0 2i" | gmt psxy -R -J -K -O -Sv1c+b+e+h0 >> $PS echo "8 1 0 1i" | gmt psxy -R -J -K -O -Sv1c+bt >> $PS echo "8 2 0 1i" | gmt psxy -R -J -K -O -Sv1c+bc >> $PS echo "8 3 0 1i" | gmt psxy -R -J -K -O -Sv1c+ba >> $PS echo "8 4 0 1i" | gmt psxy -R -J -K -O -Sv1c+bA >> $PS echo "8 5 0 1i" | gmt psxy -R -J -K -O -Sv1c+bi >> $PS echo "8 6 0 1i" | gmt psxy -R -J -K -O -Sv1c+bI >> $PS echo "5 5 2i 0 45" | gmt psxy -R -J -K -O -Sm1c+b+e+h1 -Gred>> $PS echo "5 7 2i 0 90" | gmt psxy -R -J -O -Sm1c+b+e+h1 -Gred >> $PS gmt psconvert -E150 -Tg -A -P $PS ps2pdf $PS $PDF evince $PDF rm $PS Vectors in geographic coordinate system 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 R=-100/100/-70/70 J=M7i PS=geo_arrow.

Boundary condition is necessary when we find the numerial solutions to some equations. Here, we show you some kinds of boundary contions in solving partial difference equation. 1 Dirichlet (fixed) $$ \left \{ \begin{aligned} p(t, x_{min}) &= 0\\ p(t, x_{max}) &= 0 \end{aligned} \right. \tag{1}, $$ where, $p(t, x)$ is what we want to find, let’s say, pressure in acoustic wave equation. 2 Neumann $$ \left \{ \begin{aligned} p(t, x_{min}) &= p(t, x_{min}+\Delta x)\\

New responses, if the wave field is diffuse, can be retrieved from interstaion cross-correlation of ambient noise. However, the cross-correlation time functions are asymmetric if the noise sources distribute unevenly. Here, we give you an example to show that how the cross-correlation functions vary with the angles of noise sources (red dots). We computed synthetic seismograms of earthquakes with angles from 1 to 360 degrees with an interval of 1 degree and data are recorded by two receivers (blue triangles); then we compute the cross-correlation time functions and align them with the angles; lastly, we stack all the cross-correlations to show you it’s symmetric under the condition that the noise sources distribute evenly.