Draw P and S waves illustration

Question

I need some help with drawing similar figures. Don't care about colour. Thanks.

Answer 1

Welcome! This does something of that sort. The parameters are stored in pgf keys, and the wave form in a function called wv.

\documentclass[tikz,border=3mm]{standalone}
\usetikzlibrary{3d,fadings}
\tikzfading[name=fade left,
left color=transparent!100, right color=transparent!0]
\begin{document}
\begin{tikzpicture}[x={(1cm,0cm)},y={(60:1cm)},z={(0cm,1cm)},
    line cap=round,line join=round,font=\sffamily,
 declare function={wv(\x)=-1*ifthenelse(\x<\pgfkeysvalueof{/tikz/wave/xcrit},1,0)*\pgfkeysvalueof{/tikz/wave/amplitude}*sin(\x*\pgfkeysvalueof{/tikz/wave/omega});},
 pics/pln/.style={code={
  \tikzset{wave/.cd,#1}
  \def\pv##1{\pgfkeysvalueof{/tikz/wave/##1}}
  \pgfmathsetmacro{\nextX}{\pv{xmin}+\pv{step}}
  \pgfmathsetmacro{\nextY}{\pv{ymin}+\pv{step}}
  \draw[fill=\pv{fill}] (0,0) rectangle (\pv{xmax},\pv{ymax});
 \draw foreach \Y in {\pv{ymin},\nextY,...,\pv{ymax}}
  {(0,\Y) -- (\pv{xmax},\Y)}
 foreach \X in {\pv{xmin},\nextX,...,\pv{xmax}}
    {({\X+wv(\X)},0) --
    ({\X+wv(\X)},\pv{ymax})};
 }},wave/.cd,xmin/.initial=0,xmax/.initial=1,xcrit/.initial=1,
    ymin/.initial=0,ymax/.initial=1,
    step/.initial=0.2,omega/.initial=150,amplitude/.initial=0.15,
    fill/.initial=none
 ]
 \path (0,0,0.5) node[left=1em,node font=\large]{P wave};
 \begin{scope}[canvas is xy plane at z=1]
  \pic[transform shape,fill=orange]{pln={xmax=9,xcrit=6,fill=orange!50}};
 \end{scope}
 \begin{scope}[canvas is xz plane at y=0]
  \pic[transform shape,fill=orange]{pln={xmax=9,xcrit=6,fill=orange}};
 \end{scope}
 \begin{scope}[canvas is yz plane at x=9]
  \pic[transform shape,fill=orange]{pln={xcrit=0,fill=orange!50}};
 \end{scope}
 \draw (12/5,1,1) -- ++ (0,0,0.3) -- node[fill=white] {Compressions}
 (24/5,1,1.3) -- ++ (0,0,-0.3);
 \draw (18/5,0,0) -- ++ (0,0,-0.3) -- node[fill=white] {Dilations}
 (30/5,0,-0.3) -- ++ (0,0,0.3);
 %
 \path (0,0,-1) coordinate (L1) (7,0,-1) coordinate (R1); 
 \begin{scope}[yshift=-2.5cm,wave/.cd,xcrit=6]
  \path (0,0,-0.5) node[left=1em,node font=\large]{S wave};
  \draw[fill=orange!50]
     plot[domain=0:9,samples=101,smooth] (\x,0,{wv(\x)}) -- 
     plot[domain=9:0,samples=101,smooth] (\x,1,{wv(\x)}) -- cycle;
  \foreach \Y in {0.2,0.4,0.6,0.8}
   {\draw
     plot[domain=0:9,samples=101,smooth] (\x,\Y,{wv(\x)});} 
  \foreach \X in {0.2,0.4,...,8.8}
   {\draw (\X,0,{wv(\X)}) -- (\X,1,{wv(\X)});} 
  % 
  \draw[fill=orange]
     plot[domain=0:9,samples=101,smooth] (\x,0,{-1+wv(\x)}) -- 
     plot[domain=9:0,samples=101,smooth] (\x,0,{+wv(\x)}) -- cycle;
  \foreach \Z in {0.2,0.4,0.6,0.8}
   {\draw
     plot[domain=0:9,samples=101,smooth] (\x,0,{-1+\Z+wv(\x)});} 
  \foreach \X in {0.2,0.4,...,8.8}
   {\draw (\X,0,{-1+wv(\X)}) -- (\X,0,{wv(\X)});} 
  %  
  \begin{scope}[canvas is yz plane at x=9,yshift=-1cm]
   \pic[transform shape,fill=orange]{pln={xcrit=0,fill=orange!50}};
  \end{scope} 
  \draw (15/5,0,{-1+wv(15/5)}) coordinate (auxtl)-- ++ (0,0,-0.8) coordinate (auxbl)
  (27/5,0,{-1+wv(27/5)}) coordinate (auxtr) -- ++ (0,0,-0.8) coordinate (auxbr)
  node[pos=0.5,left,inner ysep=1pt](amp) {Amplitude};
  \draw[densely dashed] (auxtl) --  (auxtr);
  \draw[stealth-stealth] (21/5,0,{-1+wv(21/5)}) -- coordinate(aux) (21/5,0,{-1+wv(27/5)});
  \draw[-] (aux) -- (amp);
  \draw[stealth-stealth] ([yshift=1mm]auxbl) -- node[below]{Wavelength}
  ([yshift=1mm]auxbr);
  \path (2,0,-3.5) coordinate (L2) (9,0,-3.5) coordinate (R2);       
 \end{scope}
 %
 \begin{scope}[canvas is xy plane at z=0]
  \pgflowlevelsynccm
  \draw[blue!50,line width=4pt,-stealth,path fading=fade left] (L1) -- (R1);
  \draw[blue!50,line width=4pt,-stealth,path fading=fade left] (L2) -- (R2);
 \end{scope}
\end{tikzpicture}
\end{document}

If you wish to smoothen out the transition, this is also possible. However, if you want to employ simple smooth functions such as tanh for that purpose, you might need the fpu library.

\documentclass[tikz,border=3mm]{standalone}
\usetikzlibrary{3d,fadings,fpu}
\pgfmathdeclarefunction{wv}{1}{%
\begingroup%
\pgfkeys{/pgf/fpu,/pgf/fpu/output format=fixed}%
\pgfmathparse{(tanh(2*(#1-\pgfkeysvalueof{/tikz/wave/xcrit}))-1)*%
\pgfkeysvalueof{/tikz/wave/amplitude}*sin(#1*\pgfkeysvalueof{/tikz/wave/omega})}%
\pgfmathsmuggle\pgfmathresult\endgroup%
}

\tikzfading[name=fade left,
left color=transparent!100, right color=transparent!0]
\begin{document}
\begin{tikzpicture}[x={(1cm,0cm)},y={(60:1cm)},z={(0cm,1cm)},
    line cap=round,line join=round,font=\sffamily,
 pics/pln/.style={code={
  \tikzset{wave/.cd,#1}
  \def\pv##1{\pgfkeysvalueof{/tikz/wave/##1}}
  \pgfmathsetmacro{\nextX}{\pv{xmin}+\pv{step}}
  \pgfmathsetmacro{\nextY}{\pv{ymin}+\pv{step}}
  \draw[fill=\pv{fill}] (0,0) rectangle (\pv{xmax},\pv{ymax});
 \draw foreach \Y in {\pv{ymin},\nextY,...,\pv{ymax}}
  {(0,\Y) -- (\pv{xmax},\Y)}
 foreach \X in {\pv{xmin},\nextX,...,\pv{xmax}}
    {({\X+wv(\X)},0) --
    ({\X+wv(\X)},\pv{ymax})};
 }},wave/.cd,xmin/.initial=0,xmax/.initial=1,xcrit/.initial=1,
    ymin/.initial=0,ymax/.initial=1,
    step/.initial=0.2,omega/.initial=150,amplitude/.initial=0.1,
    fill/.initial=none
 ]
 \path (0,0,0.5) node[left=1em,node font=\large]{P wave};
 \begin{scope}[canvas is xy plane at z=1]
  \pic[transform shape,fill=orange]{pln={xmax=9,xcrit=6,fill=orange!50}};
 \end{scope}
 \begin{scope}[canvas is xz plane at y=0]
  \pic[transform shape,fill=orange]{pln={xmax=9,xcrit=6,fill=orange}};
 \end{scope}
 \begin{scope}[canvas is yz plane at x=9]
  \pic[transform shape,fill=orange]{pln={xcrit=0,fill=orange!50}};
 \end{scope}
 \draw (12/5,1,1) -- ++ (0,0,0.3) -- node[fill=white] {Compressions}
 (24/5,1,1.3) -- ++ (0,0,-0.3);
 \draw (18/5,0,0) -- ++ (0,0,-0.3) -- node[fill=white] {Dilations}
 (30/5,0,-0.3) -- ++ (0,0,0.3);
 \draw (6,1,1) -- ++ (0,0,0.1) node[above right] {Undisturbed medium};
 %
 \path (0,0,-1) coordinate (L1) (7,0,-1) coordinate (R1); 
 \begin{scope}[yshift=-2.5cm,wave/.cd,xcrit=6,amplitude=0.15]
  \path (0,0,-0.5) node[left=1em,node font=\large]{S wave};
  \draw[fill=orange!50]
     plot[domain=0:9,samples=101,smooth] (\x,0,{wv(\x)}) -- 
     plot[domain=9:0,samples=101,smooth] (\x,1,{wv(\x)}) -- cycle;
  \foreach \Y in {0.2,0.4,0.6,0.8}
   {\draw
     plot[domain=0:9,samples=101,smooth] (\x,\Y,{wv(\x)});} 
  \foreach \X in {0.2,0.4,...,8.8}
   {\draw (\X,0,{wv(\X)}) -- (\X,1,{wv(\X)});} 
  % 
  \draw[fill=orange]
     plot[domain=0:9,samples=101,smooth] (\x,0,{-1+wv(\x)}) -- 
     plot[domain=9:0,samples=101,smooth] (\x,0,{+wv(\x)}) -- cycle;
  \foreach \Z in {0.2,0.4,0.6,0.8}
   {\draw
     plot[domain=0:9,samples=101,smooth] (\x,0,{-1+\Z+wv(\x)});} 
  \foreach \X in {0.2,0.4,...,8.8}
   {\draw (\X,0,{-1+wv(\X)}) -- (\X,0,{wv(\X)});} 
  %  
  \begin{scope}[canvas is yz plane at x=9,yshift=-1cm]
   \pic[transform shape,fill=orange]{pln={xcrit=0,fill=orange!50}};
  \end{scope} 
  \draw (15/5,0,{-1+wv(15/5)}) coordinate (auxtl)-- ++ (0,0,-0.8) coordinate (auxbl)
  (27/5,0,{-1+wv(27/5)}) coordinate (auxtr) -- ++ (0,0,-0.8) coordinate (auxbr)
  node[pos=0.5,left,inner ysep=1pt](amp) {Amplitude};
  \draw[densely dashed] (auxtl) --  (auxtr);
  \draw[stealth-stealth] (21/5,0,{-1+wv(21/5)}) -- coordinate(aux) (21/5,0,{-1+wv(27/5)});
  \draw[-] (aux) -- (amp);
  \draw[stealth-stealth] ([yshift=1mm]auxbl) -- node[below]{Wavelength}
  ([yshift=1mm]auxbr);
  \path (2,0,-3.5) coordinate (L2) (9,0,-3.5) coordinate (R2);       
 \end{scope}
 %
 \begin{scope}[canvas is xy plane at z=0,sharp corners]
  \pgflowlevelsynccm
  \draw[blue!50,line width=4pt,-stealth,path fading=fade left] (L1) -- (R1);
  \draw[blue!50,line width=4pt,-stealth,path fading=fade left] (L2) -- (R2);
 \end{scope}
\end{tikzpicture}
\end{document}

This smooth version also looks better when animated.

\documentclass[tikz,border=3mm]{standalone}
\usetikzlibrary{3d,fadings,fpu}
\pgfmathdeclarefunction{wv}{1}{%
\begingroup%
\pgfkeys{/pgf/fpu,/pgf/fpu/output format=fixed}%
\pgfmathparse{(tanh(2*(#1-\pgfkeysvalueof{/tikz/wave/xcrit}))-1)*%
\pgfkeysvalueof{/tikz/wave/amplitude}*sin(#1*\pgfkeysvalueof{/tikz/wave/omega}+\pgfkeysvalueof{/tikz/wave/phase})}%
\pgfmathsmuggle\pgfmathresult\endgroup%
}
\tikzset{pics/pln/.style={code={
  \tikzset{wave/.cd,#1}
  \def\pv##1{\pgfkeysvalueof{/tikz/wave/##1}}
  \pgfmathsetmacro{\nextX}{\pv{xmin}+\pv{step}}
  \pgfmathsetmacro{\nextY}{\pv{ymin}+\pv{step}}
  \draw[fill=\pv{fill}] (0,0) rectangle (\pv{xmax},\pv{ymax});
  \clip (0,0) rectangle (\pv{xmax},\pv{ymax});
 \draw foreach \Y in {\pv{ymin},\nextY,...,\pv{ymax}}
  {(0,\Y) -- (\pv{xmax},\Y)}
 foreach \X in {\pv{xmin},\nextX,...,\pv{xmax}}
    {({\X+wv(\X)},0) --
    ({\X+wv(\X)},\pv{ymax})};
 }},wave/.cd,xmin/.initial=0,xmax/.initial=1,xcrit/.initial=1,
    ymin/.initial=0,ymax/.initial=1,
    step/.initial=0.2,omega/.initial=150,amplitude/.initial=0.1,
    fill/.initial=none,phase/.initial=0}
\tikzfading[name=fade left,
left color=transparent!100, right color=transparent!0]
\begin{document}
\foreach \Phase in {0,20,...,340}
{\begin{tikzpicture}[x={(1cm,0cm)},y={(60:1cm)},z={(0cm,1cm)},
    line cap=round,line join=round,font=\sffamily,wave/phase=\Phase]
 \path (0,0,0.5) node[left=1em,node font=\large]{P wave};
 \begin{scope}[canvas is xy plane at z=1]
  \pic[transform shape,fill=orange]{pln={xmax=9,xcrit=6,fill=orange!50}};
 \end{scope}
 \begin{scope}[canvas is xz plane at y=0]
  \pic[transform shape,fill=orange]{pln={xmax=9,xcrit=6,fill=orange}};
 \end{scope}
 \begin{scope}[canvas is yz plane at x=9,wave/phase=0]
  \pic[transform shape,fill=orange]{pln={xcrit=0,fill=orange!50}};
 \end{scope}
 %
 \path (0,0,-1) coordinate (L1) (7,0,-1) coordinate (R1); 
 \begin{scope}[yshift=-2.5cm,wave/.cd,xcrit=6,amplitude=0.15]
  \path (0,0,-0.5) node[left=1em,node font=\large]{S wave};
  \draw[fill=orange!50]
     plot[domain=0:9,samples=101,smooth] (\x,0,{wv(\x)}) -- 
     plot[domain=9:0,samples=101,smooth] (\x,1,{wv(\x)}) -- cycle;
  \foreach \Y in {0.2,0.4,0.6,0.8}
   {\draw
     plot[domain=0:9,samples=101,smooth] (\x,\Y,{wv(\x)});} 
  \foreach \X in {0.2,0.4,...,8.8}
   {\draw (\X,0,{wv(\X)}) -- (\X,1,{wv(\X)});} 
  % 
  \draw[fill=orange]
     plot[domain=0:9,samples=101,smooth] (\x,0,{-1+wv(\x)}) -- 
     plot[domain=9:0,samples=101,smooth] (\x,0,{+wv(\x)}) -- cycle;
  \foreach \Z in {0.2,0.4,0.6,0.8}
   {\draw
     plot[domain=0:9,samples=101,smooth] (\x,0,{-1+\Z+wv(\x)});} 
  \foreach \X in {0.2,0.4,...,8.8}
   {\draw (\X,0,{-1+wv(\X)}) -- (\X,0,{wv(\X)});} 
  %  
  \begin{scope}[canvas is yz plane at x=9,yshift=-1cm,wave/phase=0]
   \pic[transform shape,fill=orange]{pln={xcrit=0,fill=orange!50}};
  \end{scope} 
  \path (2,0,-3.5) coordinate (L2) (9,0,-3.5) coordinate (R2);       
 \end{scope}
 %
 \begin{scope}[canvas is xy plane at z=0,sharp corners]
  \pgflowlevelsynccm
  \draw[blue!50,line width=4pt,-stealth,path fading=fade left] (L1) -- (R1);
  \draw[blue!50,line width=4pt,-stealth,path fading=fade left] (L2) -- (R2);
 \end{scope}
\end{tikzpicture}}
\end{document}