Location: Arthur's Pass
Date (NZ Summer Time): Saturday, March 9 1929 at 10:50 pm
Epicentre: 42.84°S, 171.83°E
Focal Depth: 11 km
Maximum Intensity: MM 9
Magnitude: MS 7.1
At 10:50 pm local time on March 9 1929, a severe earthquake struck the small, isolated communities of Arthur's Pass and Otira, toppling chimneys and throwing furniture. The earthquake was felt throughout the South Island and as far north as Taranaki and Napier in the North Island rocking for four minutes.
Nearly continuous tremors followed for an hour, and aftershocks continued for days.
During the magnitude 7.1 a 900-metre-high section of mountain peak collapsed onto Taruahuna Pass, close to the epicentre. The landslide continued partway up the flanks of Mt Franklin opposite. It then slid about 5 kilometres down the remote valley of the west branch of the Otehake River. The collapsed peak was later dubbed Falling Mountain.

Read further:
Historic earthquakes - The 1929 Arthur’s Pass and Murchison earthquakes.Te Ara - The Encyclopedia of New Zealand