Other Hazards
Oahu is prone to many hazards that can affect you, your family, your home, and your community. Being aware and taking action to protect yourself from these hazards can greatly reduce damage and loss of life should one occur in your area.
Earthquake
Earthquake is a term used to describe both the sudden slip of a fault, and the resulting ground shaking and radiated seismic energy caused by the slip, by volcanic or magmatic activity, or other sudden stress changes in the earth.
Am I at risk?
Earthquakes are generally infrequent and of low-magnitude on Oahu; however, strong or damaging earthquakes have occurred on or near the island in the past and are likely to occur again in the future. Seismic hazard on Oahu was historically
underestimated. In the late 1980’s, Oahu was recognized to be in a region of moderate seismic hazard, and building standards were improved beginning in 1990.
What should I do if I feel an earthquake?
In the event of an earthquake, take the following protective actions:
- Indoors: Drop, cover, and hold on. Drop quickly to the floor and take cover beneath a strong desk or table. Cover your head if possible and hold on tight until the shaking stops. If no cover is available, get down on the floor next to an interior wall while covering your head and neck with your arms.
Stay away from windows, mirrors, bookcases or shelves, heavy objects like big appliances or glass. All of these items can be deadly. Do not go outside until you can safely exit the building! When you exit use stairways only. Do not be surprised if fire alarms or sprinklers activate. - In bed: If you are in bed, hold on and stay there, protecting your head and neck with a pillow. You are less likely to be injured staying where you are. Broken glass on the floor has caused injury to those who have rolled to the floor or tried to get to doorways.
- In a wheelchair: Lock the wheels once you are in a safe position. If unable to move quickly, stay where you are. Cover your head and neck with your arms.
- Outdoors: Move to a clear area if you can safely do so; avoid power lines, trees, signs, buildings, vehicles, and other hazards.
- Driving: Pull over to the side of the road, stop, and set the parking brake. Avoid overpasses, bridges, power lines, signs and other hazards. Stay inside the vehicle until the shaking is over. If a power line falls on the car, stay inside until a trained person removes the wire.
- Below a dam: Dams can fail during a major earthquake. Catastrophic failure is unlikely, however, if you live downstream from a dam or reservoir, you should know if you live in a dam evacuation zone and have prepared an evacuation plan.
Know the natural tsunami warning signs.
Be aware that earthquakes can generate a local tsunami with minimal warning time. If you observe these natural warning signs, evacuate coastal areas and move to higher ground.
Where have there been earthquakes in Hawaii?
The United States Geological Survey (USGS) shows all of Hawaii’s recent earthquakes on this map.
High Surf
The National Weather Service will issue High Surf Advisories and Warnings when the surf is forecast to be higher than normal on affected shorelines.
A High Surf Warning means that damaging surf is expected or already occurring along the affected shorelines.
A High Surf Advisory means that waves along the affected shores will be higher than normal.
Residents and visitors are urged to avoid entering the water due to the dangerous wave action and strong rip currents.
As each shoreline handles waves differently, the National Weather Service Forecast Office in Honolulu uses the criteria in the chart below for the issuance of High Surf Advisories and Warnings in coordination with emergency management, responders, and water safety organizations on Oahu.
Am I at risk?
High surf, while having the potential to threaten any of the island’s exposed coast line, is more common and dangerous on Oahu’s north and west shores during the months of October through March. While the National Weather Service issues High Surf Advisories, it is incumbent upon every resident and visitor living or staying on or near exposed shorelines to be prepared to take precaution if conditions seem hazardous, even before a warning or advisory is in effect. Always heed warnings by ocean safety personnel.
How can I protect myself and my family from high surf?
- Always check ocean conditions before venturing out to the beach, IF IN DOUBT, DON’T GO OUT! Visit the City and County of Honolulu’s Ocean Safety Division to learn more about staying safe during a high surf event.
- Residents and visitors driving or walking along coastal roads and highways should be careful of sand and seawater that may wash across the road.
- All beachgoers along affected shorelines need to exercise extreme caution when near the ocean, stay well out of the water, away from peninsulas and reef areas overlooking the ocean and be aware of sudden hazardous changes in ocean behavior.
- Please heed all warnings from Ocean Safety Lifeguards and emergency personnel.
- In addition, high surf that coincides with periods of higher than normal tides can impact homes. Residents living in homes along or near affected shoreline’s should consider measures to protect their property and prepare to evacuate to a safer location if necessary.
Always remember, don’t turn your back to the ocean!
High Wind
Winds on Oahu originate from three main sources: trade winds, Kona winds, and tropical cyclones (hurricanes and tropical storms). For the purpose of this section we will focus on trade winds and Kona winds and their associated hazards.
Trade Winds
On Oahu, northeast and east-northeast “trade winds” occur about 70% of the time. North Pacific high pressure systems are responsible for the majority of the gusty trade winds over Hawaiian waters, which commonly persist for several days before tapering off.
Kona Winds
“Kona” winds is the term used for the stormy, rain-bearing winds that blow over the islands from the southwest or south-southwest, from the opposite direction of trade winds. Kona winds can become very strong in the winter when storm systems, moving across the central North Pacific, draw air from the south.
Kona winds are most likely to occur during the winter and spring seasons. Damaging Kona winds have reached velocities of 50 miles per hour for several days on end.
Am I at risk?
Trade winds between 25 and 60 mph, that can trigger High Wind Watches or Warnings, can occur for several days when a sub-tropical high pressure system intensifies passes north of the islands. The east-facing coastlines of Oahu are most impacted by these trade winds.
Kona storms may be persistent and can last up to two weeks. On land, effects of strong Kona winds can be very dramatic. It is not uncommon for trees to be uprooted, branches downed, and roofs blown off houses. When paired with mountainous topography, downslope winds can increase and can be very destructive to land in low lying areas. The Kaneohe-Kahaluu area, below the Koolau Mountains, has had extensive wind damage due to strong Kona winds. Kona storms reverse usual trade wind patterns so the leeward sides of the island are most impacted.
How will I be notified when there is a high wind event?
A High Wind Watch, Warning, or Advisory may be issued by the National Weather Service (NWS) based on the following wind speeds:
- A High Wind Watch is issued when sustained winds exceeding 40 mph and/or frequent gusts over 60 mph are likely to develop in the next 24 to 48 hours.
- A High Wind Warning is issued when sustained winds exceeding 40 mph and/or frequent gusts over 60 mph are occurring or imminent.
- A Wind Advisory is issued when sustained winds of 30 to 39 mph and/or frequent gusts to 50 mph or greater are occurring or imminent.
Sign up for HNL Info alerts and to monitor TV and radio to ensure you are aware when a high wind event is approaching. It is important to stay inside during these events to prevent injury. Learn more on our Stay Informed page.
How can I PREPARE for a high wind event?
Trim tree branches away from your house and power lines.- Secure loose gutters and shutters.
- Update your 14-Day Disaster Supply Kit and be sure to include enough food and water to last for 14 days for each person in your home.
- Make a list of items outside your home, including on your lanai, that you will need to tie down or put away so they don’t blow away or fly through a window. Immediately secure these items to avoid damage or injury once the wind starts picking up.
- Postpone outdoor activities if a wind advisory or high wind warning has been issued, the safest place to be during high winds is indoors.
What should I do DURING a high wind event?
Stay indoors! Stay inside a sturdy building during a high wind warning or severe thunderstorm warning. Listen to the local news, official social media, HNL Info, or NOAA Weather Radio for updates.
- Take cover next to a building or under a shelter.
- Stand clear of roadways, as a gust may blow you into the path of an oncoming vehicle.
- Use handrails where available on outdoor walkways and avoid other elevated areas such as roofs without adequate railing.
- Watch for flying debris. Tree limbs may break and street signs may become loose during strong wind gusts. Keep an eye toward nearby lanais for loose objects that may fall.
- Watch for objects blowing across the roadway and into your path.
- Slow down and keep a safe distance from other vehicles.
- High-profile vehicles such as trucks, vans, and SUVs, or vehicles towing trailers, are more prone to be pushed or even flipped by high wind gusts.
- If winds are severe enough to prevent safe driving, get onto the shoulder of the road and stop, make sure you are away from trees or other tall objects that could fall onto your vehicle. Stay in the car and turn on the hazard lights until the wind subsides.
- Report downed lines to the 911. Do not try to free lines or to remove debris yourself.
- Avoid anything that may be touching downed lines, including vehicles or tree branches. Puddles and even wet ground can conduct electricity in some cases. Warn others to stay away.
- If you see someone who has been shocked who may be in direct or indirect contact with a power line, do not try to touch them. You may become a second victim. Get medical attention as quickly as possible by calling 911.
- Remain where you are, if possible, and wait for help.
- If you must get out of the car because of a fire or some other hazard, jump free of the car, hopping with both feet together so that your body clears the vehicle before touching the ground.
- Never step down or simultaneously touch the ground and equipment that is in contact with the power line, as this will increase the risk of electric shock.
- Once you clear the car, shuffle at least 30 feet away, with both feet on the ground.
How can I stay safe AFTER a high wind event?
- Do not go near downed power lines. Call 911 to report downed power lines.
- Continue to listen to the local news, official social media, HNL Info, and NOAA Weather Radio for updates following the storm.
- If you lose power and are using a generator, be sure to review generator safety tips.
Landslides and Rockfalls
A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. Debris flows (commonly referred to as mudflows or mudslides) and rock falls are examples of common landslide types.
Am I at risk?
If you live in a residence located at the base of a cliff or hillside you could be at risk from landslide or rock falls. In addition, many of Oahu’s highways and roads are in areas at risk to landslide and rock fall.
Oahu has several of the essential components for landslide and rock fall hazards:
- Steep hillsides
- Heavy rainfall
- Highways near steep slopes and residential development in upland areas.
Landslides are dangerous because they occur suddenly and can move rapidly by flowing or avalanching downhill slopes and channels. They generally occur during, or immediately after, severe rainfall of more than 3 inches in a peak 6-hour period.
Rock falls on Oahu have resulted in loss of life and property damage. For example, in 2002 a section of Hawaii Kai was evacuated after a boulder rolled onto a resident’s car. In addition, in 2018, a boulder estimated at five tons crashed into a Manoa home late at night. Although no one was injured, that boulder and subsequent other rocks did damage to several homes in that area.
How can I protect myself, my family, and my home from a landslide?
- Get an assessment of your property by a qualified geotechnical professional.
- Consult a professional for advice on appropriate preventative measures for your home or business, such as flexible pipe fittings, which can better resist breakage.
- Protect your property based on of recommendations from a qualified geotechnical professional on protection from debris flow and flooding. You can’t stop or change the path of a debris flow. However, you may be able to protect your property from floodwaters or mud by using certain techniques that they may recommend.
- If you are at risk from a landslide talk to your insurance agent. Debris flow may be covered by flood insurance policies from the National Flood Insurance Program (NFIP).
Other severe weather: Tornados, Waterspouts, Severe Thunderstorms
Severe weather refers to any dangerous meteorological phenomena with the potential to cause damage, serious social disruption, or loss of human life.
Am I at risk?
In addition to hurricanes, tropical cyclones, flash flooding, and high wind events, severe weather in Hawaii can also include severe thunderstorms, tornados and waterspouts.
- A tornado is a violently rotating column of air extending from the base of a thunderstorm down to the ground. Tornados are capable of completely destroying well-made structures, uprooting trees, and hurling objects through the air like deadly missiles.
- Tornadic waterspouts are tornados that form over water, or move from land to water. They have the same characteristics as a land tornado. They are associated with severe thunderstorms, and are often accompanied with high winds and seas, large hail, and frequent dangerous lightning.
- A severe thunderstorm is a thunderstorm that produces a tornado, winds of at least 58 mph, and/or hail at least 1″ in diameter.
How will I know if there is severe weather approaching?
The National Weather Service Honolulu Forecast Office will issue emergency information regarding tornados. Learn more on our Stay Informed page.
Be prepared to take action if you hear the following messages broadcasted via the Emergency Alert System (EAS) TV and radio, or if you receive an HNL Info alert:
TORNADO WATCH: Strong thunderstorms capable of producing tornados are possible. If you are in the area of a Tornado Watch, you should be prepared to take shelter from thunderstorms. Tornados may develop with little warning. Tornado Watches are generally issued for 6 hour periods.
TORNADO WARNING: A tornado is occurring or developing in a strong thunderstorm. If you are in the area of a Tornado Warning you should stay inside, away from windows, and be prepared for strong winds and large hail. If you see a tornado and/or are in its path, go to the central portion of a substantial structure, like a building, and seek shelter under a heavy piece of furniture if possible, or in a closet or other small protected room. Tornado warnings are generally in effect for less than 1 hour.
SEVERE THUNDERSTORM WATCH: Severe thunderstorms are possible in your area, you should be prepared to take shelter from thunderstorms. Severe Thunderstorm Watches are generally issued for 6 hour periods.
SEVERE THUNDERSTORM WARNING: Severe thunderstorms are occurring or could form at any time. If you are in the area of a severe thunderstorm, you should take shelter indoors immediately, avoid windows and be prepared for high winds and hail. Severe Thunderstorm Warnings are generally in effect for an hour or less.
How can I protect myself and my family from severe weather?
- The most important thing to know is: “When Thunder Roars, Go Indoors!” visit the National Weather Service’s webpage on Lightning Safety Awareness to learn more about staying safe during thunderstorms.
- Purchase a NOAA Weather Radio and become familiar with its uses and operation.
- Tornados can develop rapidly with little or no warning. Remember, seek shelter immediately. Flying debris are responsible for most tornado related deaths and injuries.
- Being in a vehicle during a tornado is not safe. The best course of action is to drive to the closest shelter. If you are unable to make it to a safe shelter, either get down in your car and cover your head, or abandon your car and seek shelter in a low lying area such as a ditch or ravine.
- Waterspouts appearing over the ocean or lakes can be just as hazardous as a tornado. Seek immediate shelter.
Terrorism and Acts of Mass Violence
Terrorism and mass violence events are included on our list of hazards that can affect the City and County of Honolulu because of the suddenness of their onset, high emotional impact, and ability to cause mass casualties.
How can I help keep Oahu safe?
Visit the Department of Homeland Security’s page on “If you See Something, Say Something” to recognize the signs of terrorism-related suspicious activity.- The Honolulu Police Department Major Events Division can visit your school, work, or community to give a presentation on active shooter safety.
- For more information on terrorism awareness, visit the State of Hawaii Office of Homeland Security.
Hazardous Materials (HAZMAT) Incident
Hazardous materials come in the form of explosives, flammable and combustible substances, poisons, and radioactive materials. Hazards can occur during production, storage, transportation, use or disposal.
Am I at risk?
With the mixture of residential, agricultural, and manufacturing properties around the island, and the expansion of the number of chemical storage/use sites, hazardous materials incidents can effect many segments of the City’s population.
Hazardous material releases/spills could occur quickly and with little to no warning, with each event having different consequences. You and your community are at risk if a chemical is used unsafely or released in harmful amounts into the environment where you live, work, or play.
What should I do if there is a HAZMAT release?
If there is ever a HAZMAT release/spill in your area, it is important to listen to official emergency information issued by authorities via public address, TV, radio, HNL Info, and official social media regarding guidance on evacuation or sheltering-in-place.
If you suspect there might have been a release of hazardous materials in your area, immediately call 911 and tell them that you believe there might have been a HAZMAT release.
Learn more about HAZMAT response and reporting by visiting the City’s Local Emergency Planning Committee’s (LEPC) webpage.