\documentclass[12pt,border=0pt,tikz,class=scrartcl,multi=false]{standalone}
\usepackage{times}
\usepackage{pgfplots}
\pgfplotsset{compat=1.10}
\usetikzlibrary{arrows,decorations.text}

\usepackage{tikz-3dplot}

\pagestyle{empty}
\begin{document}
\def\LA{2}
\def\Lb{1.5}
\def\gap{1.5cm}
\tdplotsetmaincoords {-60}{70}
\begin{tikzpicture}[thick,auto,>=stealth',xscale=4,yscale=3,tdplot_main_coords]
\begin{scope} [xshift=-\gap]
	\draw [->] (0,0,0) -- (-\LA,0,0) node [anchor=south,gray] {Geographic North};
	\draw [->] (0,0,0) -- (0,\LA,0) node [anchor=south,gray] {Geographic East};
	\draw [->] (0,0,0) -- (0,0,\LA) node [pos=.9,right,gray] {Down};
	\draw [->,blue,very thick] (0,0,0) -- (-\Lb,0,0) node [anchor=south] {x};
	\draw [->,blue,very thick] (0,0,0) -- (0,\Lb,0) node [anchor=south] {y};
	\draw [->,blue,very thick] (0,0,0) -- (0,0,\Lb) node [left] {z};
	\draw [->,red,line width=2pt] (0,0,0) -- (-\Lb,\Lb,\Lb);
	\draw [gray] (-\Lb,0,0) --   (0,\Lb,0) --   (\Lb,0,0) 
		--   (0,0,\Lb) --   (-\Lb,0,0) --   (0,0,-\Lb)
		(-\Lb,0,0) --   (0,0,\Lb) --   (\Lb,0,0) --   (0,\Lb,0)
		(-\Lb,0,\Lb) --   (0,\Lb,0)
	;
\end{scope}
\begin{scope} [xshift=\gap]
	\draw [->] (0,0,0) -- (-\LA,0,0) node [anchor=south,gray] {Geographic North};
	\draw [->] (0,0,0) -- (0,\LA,0) node [anchor=south,gray] {Geographic East};
	\draw [->] (0,0,0) -- (0,0,\LA) node [pos=.9,right,gray] {Down};
	\draw [->,red,line width=2pt] (0,0,0) -- (-\Lb,\Lb,\Lb);
	\draw [thin,cyan,postaction={decoration={text along path,
			raise=-10pt,text color=cyan,text align={center},
			text={Intensity} },decorate}] 
		(0,0,0) -- (-\Lb,\Lb,\Lb);
	\tdplotsetthetaplanecoords{135};
	%\tdplotdrawarc [tdplot_rotated_coords,cyan] {(0,0,0)} {.8} {55}{90}{above right=5pt and 0pt}{Inclination};
	\draw [tdplot_rotated_coords,fill=cyan,fill opacity=.3,cyan] (0,.8,0)
		arc (90:55:.8) node [pos=.1,right,opacity=1] {Inclination}
		-- (0,0,0);
	%\tdplotdrawarc [cyan,fill=cyan] {(0,0,0)} {.6} {180}{135}{above}{Declination};
	\draw [cyan,fill=cyan,fill opacity=.3] (0,0,0) -- (-.6,0,0) 
		arc (180:135:.6) node [above,pos=.5,opacity=1] {Declination};
	\draw [gray] (-\Lb,0,0) --   (0,\Lb,0) --   (\Lb,0,0) 
		--   (0,0,\Lb) --   (-\Lb,0,0) --   (0,0,-\Lb)
		(-\Lb,0,0) --   (0,0,\Lb) --   (\Lb,0,0) --   (0,\Lb,0)
		(-\Lb,0,\Lb) --   (0,\Lb,0)
	;
	\draw [->,red,dashed, line width=1.5pt] (0,0,0) -- (-\Lb,\Lb,0) node [anchor=south] {Magnetic North};
	\draw [fill=blue,draw=none] (0,0,0) circle (.5pt)	(-\Lb,\Lb,\Lb) circle (.5pt);
\end{scope}
\end{tikzpicture}
\end{document}