Natural Hazard & Risk
Natural hazards and risks are key considerations for outdoor adventures in New Zealand. Whether exploring the majestic Milford Sound, the Te Anau Glowworm Caves, or engaging in thrilling activities like white-water rafting, visitors must be aware of potential dangers. Here we cover natural hazards and risks that you should be aware of when partaking in our experiences.
Milford Sound
Nestled amidst towering cliffs and lush rainforests, the breathtaking beauty and raw nature of Milford Sound captivate all who visit, but it also comes with its share of natural hazards. Visitors to Milford Sound should be aware of various natural hazards, including earthquakes, tsunamis, severe weather events, flooding, landslides, and avalanches. The Alpine Fault, capable of producing Magnitude 8 earthquakes, poses a significant risk of triggering landslides and tsunamis, while the area's mountainous terrain and high rainfall lead to frequent landslides and potential road closures due to flooding and avalanches.
Earthquake
The Alpine Fault runs approximately 800km up the spine of the South Island of New Zealand and is one of the world’s major geological features. Responsible for the prominent geological features that are evident in Milford Sound, the Alpine Fault is active, with rupture events occurring on average every 300 years. The latest significant earthquake was in 1717 AD. For more information, see the link here: AF8 website.
Analysis indicates that major ruptures are likely to exceed Magnitude 8. The next Alpine Fault event is likely to be very destructive and could trigger landslides and potentially a localised tsunami. An Alpine Fault rupture of Magnitude 8 is anticipated to damage critical infrastructure in Milford Sound, such as key road networks.
Tsunami
Milford Sound is susceptible to both local and distant-sourced tsunami events. Scientific analysis indicates that in the event of any severe earthquake (Magnitude 8 or higher), a destructive landslide (including submarine) induced tsunami could be generated. Supporting analysis also indicates that the substantial volume of water displaced by a landslide may result in a tsunami reaching very significant wave and run-up heights.
In areas such as Milford Sound, where numerous visitors are received each day, a landslide-induced tsunami of any significant height would pose 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. MSTL is currently seeking a risk assessment related to landslide-induced tsunamis. This Notice will be updated after the risk assessment has been received and considered.
Severe Weather Events
Flooding
Milford Sound’s mountainous terrain results in significant annual rainfall, with the area receiving in excess of 7 metres of rain each year on average. Low soil absorption typically sees rain run directly into the sea, lakes, or high-capacity rivers throughout the area. It is not unusual to get rainfall accumulations of 200 mm in 24 hours with intensities of up to 30 mm per hour.
Whilst the roading infrastructure is well developed to cope with most heavy rain events, significant and sustained rain events have the potential to close roads and isolate Milford Sound while repairs are carried out.
Landslide
Landslides are a regular occurrence in Milford Sound due to regular severe weather and the area's soil conditions. They are primarily vegetation-based near the coast, where topsoil is limited; however, further inland, they have a higher content of rock and soil.
Snow/ Avalanche
Avalanches also threaten the road networks that service the Milford Sound area. While the preventative actions of the Milford Road Alliance (i.e. avalanche control) significantly reduce avalanche risk, avalanches continue to occur periodically.
Te Anau Glowworm Caves:
Glowworm Cave Exploration with RealNZ offers a unique adventure into the Te Anau Cave system, situated beside Lake Te Anau, where the glow of bioluminescent creatures illuminates the darkness. As you embark on this subterranean journey, it's essential to recognise the potential risks involved, including navigating along elevated walkways, restricted access at the entrance, uneven surfaces, flooding, and the possibility of earthquakes in the region. With a single point of access to the cave, there is a possibility of entrapment during a significant earthquake, which heightens the emphasis on safety and careful navigation. Alongside transportation considerations, such as lake conditions and vessel safety, we prioritise your well-being by adhering to stringent safety measures and expert guidance. Rest assured, RealNZ is dedicated to ensuring your safety and delivering an unforgettable experience amidst the wonders of the underground world.
Earthquake:
The Alpine Fault runs approximately 800km up the spine of the South Island of New Zealand and is one of the world’s major geological features. Responsible for the prominent geological features in the area, the Alpine Fault is active, with rupture events occurring on average every 300 years. The latest significant earthquake was in 1717 AD. For more information, see the link here: AF8 website.
Analysis indicates that major ruptures are likely to exceed Magnitude 8. The next Alpine Fault event is likely to be very destructive and could trigger multiple landslides and rockfalls. An Alpine Fault rupture of Magnitude 8 is anticipated to cause significant changes to the natural landscape and damage critical infrastructure across most of the South Island, such as key road networks and services.
Flooding:
Flooding in caves poses significant risks, especially after heavy rainfall or upstream water events. Water levels inside the cave can rise rapidly, creating strong currents that may trap visitors or staff. Flooding could submerge cave exits, making evacuation difficult and dangerous. Monitoring weather conditions and water levels is crucial to minimise the risk of flooding.
Landslips:
Heavy rainfall or erosion can lead to landslips, particularly in hilly or unstable terrain around the cave entrance. Landslides may block access to the cave or make entrance pathways hazardous, trapping visitors inside or preventing them from entering. Regular monitoring of the surrounding terrain, coupled with weather forecasts, can help anticipate and prevent landslips.
Rockfall and Cave Collapse:
Rockfalls and cave collapses are potential hazards in caves, where loose rocks, stalactites, or sections of the cave ceiling could fall unexpectedly. This presents a risk of injury to visitors and staff and could block paths or damage equipment. Regular inspections of the cave structure help identify areas of instability and mitigate the risk of rockfalls.
Restricted spaces:
Many caves feature narrow or confined spaces that can trigger anxiety or panic in individuals prone to claustrophobia. Additionally, narrow passages may hinder quick evacuations in case of emergencies. Proper briefings before entering the cave and offering alternative routes or tours for those uncomfortable with confined spaces can help mitigate this hazard.
Darkness and Limited Visibility:
Caves are inherently dark, often illuminated only by glowworms or limited artificial lighting. The low visibility increases the risk of visitors becoming disoriented, slipping, or misjudging steps. Accidents can occur, especially during the punt ride or while navigating uneven cave terrain. Adequate lighting and clear guidance from tour operators are vital to ensure safety.
Hypothermia or Cold Stress:
Cave environments are often cold and damp, which can lead to hypothermia or cold stress if visitors or staff are exposed to cold water or low temperatures for extended periods. This risk is heightened during the punt ride if individuals come into contact with cold water. Providing warm clothing, briefings on cave conditions, and limiting exposure times are important controls.
Fast-moving and/or deep/shallow water:
The presence of fast-moving water in the cave system or surrounding areas can pose significant risks during activities like punt rides or cave exploration. The intention is to always stay within the punt and on designated walkways and to avoid entering the water. Visitors traveling with children must always supervise them to ensure safety.
Severe weather events:
Severe weather events, including thunderstorms, heavy rainfall, and flash flooding, pose a significant risk during white water rafting. Rapid changes in water levels, strong currents, and reduced visibility can lead to accidents, including capsizing and hypothermia, endangering participants' safety. Vigilant monitoring of weather forecasts and immediate implementation of safety measures are crucial to mitigate these risks.
Medical events:
The remote nature of the experience increases the potential consequences of medical events. Injuries or illnesses can occur without immediate access to medical assistance, which may endanger participants' health. Disclosing applicable medical conditions to your guide is crucial to ensure proper risk management. Effective preparation and communication are vital for managing such incidents in remote locations.
Punt trip in the caves:
Operating punts in confined cave spaces poses unique challenges, such as overloading, instability, or mechanical failure. Visitors could fall into the water during boarding or disembarking, increasing the risk of injury or drowning. Using well-maintained equipment and following strict loading guidelines to ensure a safe punt ride experience.
Vessel transport to and from the caves:
Transporting visitors to and from the caves by vessel introduces several maritime hazards. Rough water conditions, such as strong currents, waves, or wind, can lead to seasickness, instability on deck, or difficulty docking safely. Boarding and disembarking from the vessel, especially in wet or slippery conditions, presents risks of slips, trips, and falls. Additionally, poor visibility during night tours or foggy conditions can make navigation challenging and increase the risk of collisions or grounding. Proper vessel maintenance, safety briefings, use of life jackets, and crew assistance during boarding and disembarking are key measures to ensure visitor safety. Maintaining communication with land-based teams is also critical for responding to emergencies promptly.
White Water Rafting
The Kawarau and Shotover Rivers, known for their thrilling white-water rapids and stunning scenery, also present unique natural hazards. Rafters should be aware of potential risks associated with these rivers, including rapidly changing water levels, hidden obstacles, and strong currents. While experienced guides mitigate these risks, unexpected weather events like heavy rainfall can significantly increase river flows and create challenging conditions. Additionally, the remote locations of some rafting sites can limit access to emergency services in case of accidents.
The river and its fluid nature:
The fluid nature of the river poses a continuous and unpredictable risk during white water rafting. Changes in water levels, flow patterns, submerged obstacles, and shifting currents can occur suddenly, increasing the likelihood of capsizing, collisions with obstacles, and potentially hazardous situations for participants, leading to injury, drowning, or loss of control of the raft.
Raft flips:
Flips during white water rafting pose a significant hazard to participants and can occur regularly and at any time. These flips may result in injury or drowning due to sudden immersion in fast-moving water, impact with rocks or debris, and potential entrapment under the overturned raft.
Entrapment:
Entrapment during white water rafting poses a serious risk to participants, where limbs or the body can become trapped against rocks, under the raft, or in hydraulic features. Such entrapment can lead to drowning, injury, or even death due to the powerful forces of the moving water and the difficulty of extricating oneself from the entangled situation.
Impacts:
Impacts during white water rafting present a significant risk to participants, as collisions with rocks, submerged obstacles, or other rafts can occur unexpectedly. These impacts can lead to injuries such as bruises, cuts, fractures, or head trauma and may also result in capsizing or entrapment situations, increasing the likelihood of drowning or other serious consequences.
Fast-moving and/or deep/shallow water:
Fast-moving and/or deep water presents inherent risks during white water rafting, as participants may struggle to maintain control of their raft or swim against the current. The force of the water can overpower individuals, leading to difficulty in self-rescue or retrieval by safety personnel. This increases the likelihood of drowning, exhaustion, or injury due to collisions with obstacles or entrapment in underwater hazards. Shallow water also presents a significant hazard, with an elevated risk of entrapment or impacts from objects in the river.
Rocks:
Rocks, both in the water and while moving around the water's edge, present a dual risk during white water rafting. Participants navigating the river face the danger of colliding with submerged rocks, which can lead to raft damage, capsizing, or injury. Moreover, individuals manoeuvring around the water's edge are susceptible to slipping or falling on rocks, potentially resulting in injuries such as sprains, fractures, or lacerations. These risks underscore the importance of caution and proper safety protocols during white water rafting activities.
Earthquake:
The Alpine Fault runs approximately 800km up the spine of the South Island of New Zealand and is one of the world’s major geological features. Responsible for the prominent geological features in the area, the Alpine Fault is active, with rupture events occurring on average every 300 years. The latest significant earthquake was in 1717 AD. For more information, see the link here: AF8 website.
Analysis indicates that major ruptures are likely to exceed Magnitude 8. The next Alpine Fault event is likely to be very destructive and could trigger multiple landslides and rockfalls. An Alpine Fault rupture of Magnitude 8 is anticipated to cause significant changes to the natural landscape and damage critical infrastructure across most of the South Island, such as key road networks and services.
Landslips:
Landslips pose a significant risk during white water rafting, particularly in areas with steep terrain or unstable soil conditions. Sudden landslides can dislodge rocks, trees, and debris into the river, creating hazardous obstacles for rafters. These obstacles increase the likelihood of collisions, capsizing, or entrapment, endangering participants and amplifying the complexity of rescue operations. Additionally, landslips may also trigger powerful surges of water, intensifying the force and unpredictability of the rapids, thus heightening the risk of injury or drowning for rafters.
Rockfall:
Rockfalls present a substantial risk during white water rafting, particularly in areas with steep cliffs or unstable rock formations. Sudden rockfalls can dislodge large rocks or boulders, which may cascade into the river, creating dangerous obstacles for rafters. These obstacles increase the likelihood of collisions, capsizing, or entrapment, posing significant risks to participants. Additionally, rockfalls can generate powerful waves and turbulence, exacerbating the already challenging conditions of the rapids and increasing the risk of injury, drowning, or raft damage.
Other river users:
The presence of other river users while white water rafting introduces a notable risk factor. Interaction with kayakers, jet boaters, or other rafting groups can lead to collisions, entanglements, or disruptions in navigation. Lack of coordination or communication among different river users increases the likelihood of accidents, potentially resulting in injuries, capsizing, or equipment damage. Moreover, the diverse skill levels and behaviours of other river users contribute to the unpredictability of their movements, amplifying the complexity of managing shared waterways and necessitating heightened awareness and caution from white water rafting participants.
Entering very cold water:
It's crucial to be aware of the potential effects of cold water on the body, particularly on the cardiovascular system. Cold water immersion can indeed trigger the 'cold shock response,' which includes rapid changes in heart rate, blood pressure, and breathing patterns. For individuals with underlying heart conditions or those taking heart medication, these physiological responses can pose serious risks. Rafting in cold water below 10 degrees Celsius (50 degrees Fahrenheit), especially with a high chance of swimming, requires careful consideration, particularly for individuals with pre-existing heart conditions. Consulting with your healthcare professional before engaging in such activities is strongly advised to assess individual risk factors and determine whether it's safe to participate.
Severe weather events:
Severe weather events, including thunderstorms, heavy rainfall, and flash flooding, pose a significant risk during white water rafting. Rapid changes in water levels, strong currents, and reduced visibility can lead to accidents, including capsizing and hypothermia, endangering participants' safety. Vigilant monitoring of weather forecasts and immediate implementation of safety measures are crucial to mitigate these risks.
Medical events:
The remote nature of white-water rafting increases the potential consequences of medical events. Injuries or illnesses can occur without immediate access to medical assistance, which may endanger participants' health. Disclosing applicable medical conditions to your guide is crucial to ensure proper risk management. Effective preparation and communication are vital for managing such incidents in remote river locations.
Portage:
Participants should be aware that portage, the act of carrying or dragging a raft around hazardous sections of white water, poses inherent risks during a white-water rafting trip. Hazards such as uneven terrain, swift currents, slippery rocks, and unpredictable weather conditions may increase the likelihood of accidents or injuries while undertaking portage. However, in certain conditions, portage may be the lower-risk option compared to navigating dangerous rapids. It is essential for rafters to exercise caution, utilize proper equipment, and follow the guidance of experienced guides to mitigate these risks effectively.
Vehicle transport to and from the river:
All Rafting: It's important to recognize the risks associated with transportation via bus to and from the rafting activity. While we prioritize safety measures, transportation inherently carries risks including, but not limited to, road conditions, weather, and other external factors beyond our control. We advise all passengers always to wear seat belts, adhere to safety protocols, and follow instructions provided by our staff during transit.
Shotover River Rafting:
Skippers Road, an old mining route, is notorious for its steep drop-offs and tight corners, adding potential hazards during transit. While safety measures are our priority, transportation inherently includes risks such as road conditions, slips, weather changes, potential earthquakes, and other factors beyond our control. We strongly advise all passengers always to wear seat belts, adhere to safety protocols, and follow staff instructions during transit, particularly when navigating Skippers Road.
Helicopter transport and/or equipment failure:
Helicopter transport for white water rafting presents risks during landing, take-off, and flight due to factors like adverse weather, terrain obstacles, and mechanical issues. Remote environments exacerbate emergency response complexities, necessitating thorough risk assessment and adherence to safety protocols for participant safety.
Jet Boat transport and/or equipment failure:
Prior to engaging in our activity, it's important to recognize the risks associated with transportation via Jet Boat to the rafting activity. Jet boating involves high speeds, sharp manoeuvres, and navigation through potentially turbulent waters. While safety is our top priority and our experienced drivers adhere to strict protocols, there are inherent risks involved in such activities. Factors such as river conditions, weather changes, and unforeseen obstacles could impact the journey. We require all passengers to wear the provided safety gear, remain seated, hold on tight, and always follow crew instructions.
