  Holes in nanowires have drawn significant attention in recent years because
of the strong spin-orbit interaction, which plays an important role in
constructing Majorana zero modes and manipulating spin-orbit qubits. Here, from
the strongly anisotropic leakage current in the spin blockade regime for a
double dot, we extract the full g-tensor and find that the spin-orbit field is
in plane with an azimuthal angle of 59{\deg} to the axis of the nanowire. The
direction of the spin-orbit field indicates a strong spin-orbit interaction
along the nanowire, which may have originated from the interface inversion
asymmetry in Ge hut wires. We also demonstrate two different spin relaxation
mechanisms for the holes in the Ge hut wire double dot: spin-flip cotunneling
to the leads, and spin-orbit interaction within the double dot. These results
help establish feasibility of a Ge-based quantum processor.
