  Wellington's port (CentrePort) experienced significant damage from the $M_w$
7.8 Kaik\=oura earthquake as a result of soil liquefaction, lateral spreading,
and shaking-induced damage to structures. To investigate these ill effects, and
propose mitigation measures to prevent similar damage in future earthquakes,
there was a need to quantify the variations in the depth to bedrock, shear
stiffness, and fundamental site period ($T_0$) across the port. In order to
characterize $T_0$ and develop shear wave velocity (Vs) profiles for use in
seismic site response analyses, horizontal-to-vertical (H/V) spectral ratio
measurements and active-source and passive-wavefield surface wave testing
(i.e., MASW and MAM, respectively) were performed across the port. A site
period map developed from 114 H/V spectral ratio measurements indicates several
areas of rapidly changing, complex subsurface structure. Deep (200-plus meters)
Vs profiles developed at six reference locations across the port were used to
estimate the depth to soft (Vs $>$ 760 m/s) and hard (Vs $>$ 1500 m/s) rock.
$T_0$ estimates from H/V spectral ratio measurements ($T_{0,H/V}$) at the six
reference locations are shown to be related to the depth of hard rock based on
linear viscoelastic transfer functions calculated from Vs profiles truncated at
several depths. $T_{0,H/V}$ measurements at two ground motion stations near the
port are also shown to be in reasonably good agreement with predominant periods
of maximum spectral amplification recorded during both the 2016 Kaik\=oura and
2013 Cook Strait earthquakes, despite these sites also being effected by soil
nonlinearity and potential 3D basin edge effects.
