Southern Discoveries Ltd wishes to notify our customers about the natural risks and hazards prevalent in Milford Sound, where our operations are situated.
Earthquakes
Milford Sound lies within an area susceptible to seismic activity due to the presence of the Alpine Fault, a significant geological feature spanning 800km along the South Island of New Zealand. This fault line, which influences the distinctive geological formations in Milford Sound, experiences periodic ruptures, with events occurring on average every 300 years.
These ruptures, often exceeding Magnitude 8, can result in considerable destruction, including landslides and the potential for localized tsunamis. A rupture of this magnitude could also inflict damage on critical infrastructure such as key road networks in Milford Sound.
The latest significant earthquake was in 1717AD. For more information, see the link here: AF8 [Alpine Fault Magnitude 8]
Tsunamis
Milford Sound faces the risk of both local and distant sourced tsunami events. Scientific analysis indicates in the event of any severe earthquake (Magnitude 8 or higher) a destructive landslide (including submarine) induced tsunami could be generated with devastating consequences.
Supporting analysis indicates that the displacement of a significant volume of water by landslides may lead to substantial wave heights and run-up levels. Given the influx of visitors to Milford Sound, a tsunami triggered by a landslide poses a significant risk to people at Milford Sound. The only warning these people would receive of a potential tsunami is the onset of an earthquake.
Severe Weather Events:
Flooding
The mountainous terrain of Milford Sound results in considerable annual rainfall, averaging over 7 meters per year. The region’s low soil absorption capacity often leads to rapid runoff into the sea, lakes, or high-capacity rivers. Rainfall accumulations of up to 200 mm within 24 hours, with intensities reaching 30 mm per hour, are not uncommon. While the road infrastructure is robust enough to withstand most heavy rainfall events, prolonged and intense rainfalls can lead to road closures, isolating Milford Sound until repairs are completed.
Landslides
Landslides are frequent in Milford Sound due to the combination of severe weather conditions and soil characteristics. Coastal areas can experience vegetation-based landslides due to limited topsoil, while inland regions see landslides composed of rock and soil.
Snow / Avalanches
Landslides are frequent in Milford Sound due to the combination of severe weather conditions and soil characteristics. Coastal areas can experience vegetation-based landslides due to limited topsoil, while inland regions see landslides composed of rock and soil.