A tsunamigenic earthquake with thrust faulting mechanism occurred off the Loyalty Islands, New Caledonia, in the Southern New Hebrides subduction zone on the 10^th of February 2021. The tsunami was observed at coastal gauges in the surrounding islands and in New Zealand. The tsunami was also recorded at a new DART network that was designed to enhance the tsunami forecasting capability of the Southwestern Pacific. We used the tsunami waveforms in an inversion to estimate the fault slip distribution. The estimated major slip region is located near the trench with maximum slip amount of 4 m. The computed seismic moment for the source model of 3.39 × 10²⁰ Nm (Mw 7.65) is slightly smaller than the Global Centroid Moment Tensor or USGS W-phase Moment Tensor solutions. We evaluate two tsunami forecasting approaches of selecting a pre-computed scenario and interpolating pre-computed scenarios for coastal regions in New Zealand. For the evaluation, we first computed the tsunami threat levels in New Zealand coastal regions from the earthquake source model to make a reference threat level map. The results show that the tsunami threat level maps from a pre-computed Mw 7.7 scenario located closest to the epicenter and from an interpolation of two scenarios matched the reference threat levels at most of the coastal regions. We also report on utilization of the coastal gauge and DART buoy data for updating forecasts in real-time during the event and discuss the differences between the rapid-response forecast and post-event retrospective forecasts.