The City and County of Honolulu

Tsunamis

Tsunamis are Hawai‘i’s most deadly natural disaster. They have killed more people in Hawai‘i than earthquakes, volcanic eruptions, hurricanes, and floods combined. The 1946 tsunami killed six people in coastal communities on O‘ahu at Kahuku, Punaluu, Kahana, and Waianae.

Two types of tsunamis strike our coast:

Pacific-wide tsunamis: Created by large earthquakes, they travel to Hawai‘i from distant areas like South America or Alaska.
Locally-generated tsunamis: Produced by geologic activity right here in the islands.

How are tsunamis monitored?
The Pacific Tsunami Warning Center (PTWC) monitors earthquakes and measures tsunami waves at sea. PTWC can provide several hours of warning time for a tsunami from a distant source. When a Tsunami Warning is issued, sirens will sound. (Sirens are tested on the first work day of every month at 11:45a.m.)

HOW TO AVOID BECOMING A VICTIM!

Be aware! Notice when you are in low-lying coastal areas or near streams in coastal valleys.

When you hear the sirens:

Turn on your radio or television for more information.
If you are in a tsunami evacuation zone, evacuate immediately to higher ground.

When a tsunami is generated locally:

There may not be time for the sirens to sound before waves begin coming ashore.
Your only warning of a local tsunami may be feeling the ground shake from an earthquake or seeing the sea suddenly withdraw or begin to surge inland.

If you feel a strong earthquake, move to high ground
immediately. If you are in a steel and/or concrete building, of six or more stories, move to the third floor or above and remain there until the “All Clear” is announced.

Do not return to coastal areas until you hear from County
authorities.

Dangerous waves may continue to come ashore for several hours.
No matter where a tsunami originates, the waves will wrap around an island. All sides of our island are at risk.

Remember: if you are in a low-lying coastal area, you are at risk from tsunamis.

Storm Surge

The greatest loss of life due to hurricanes is caused by coastal flooding known as storm surge. In Hawai‘i, water levels rise primarily from high waves generated by storm winds and from low atmospheric pressure near the eye of the storm Storm surge is often amplified as streams flooded by heavy rain empty into the ocean. Large, unpredictable waves and strong erratic coastal currents make any form of ocean activity dangerous.

HOW TO AVOID BECOMING A VICTIM!

Never go near the ocean during a tropical storm or hurricane.
Evacuate low-lying areas when advised by local authorities.

In Hawai‘i, tsunami evacuation zones are used as hazard zones for hurricane storm surge.

Rainfall Flooding

Flash floods are the leading cause of direct weather-related deaths in the State of Hawai‘i. Flash flooding commonly takes place in gulches, valleys and other channels that restrict the water from spreading out. Heavy rainfall causes a damaging flood event nearly every year on O‘ahu.

Why are floods so dangerous?

Flash floods can occur within a few hours or even minutes of excessive rainfall.
People underestimate the FORCE of water. Six inches of fast-moving water can knock you off your feet, and 2 feet of water will float your car!
Deaths occur when people are caught in rapidly rising flood waters.

HOW TO AVOID BECOMING A VICTIM!

Listen to your radio for the latest flash flood advisories, watches, and warnings. (*See map)
Never allow children to play near streams, culverts or ponds during heavy rains. Drowning deaths and injuries have occurred in the past.
Do not camp or park your vehicle along streams during threatening conditions. If your vehicle stalls, leave it immediately and seek higher ground.
Never try to walk, swim, or drive through flood waters.
If you come upon flood waters, STOP! You will not know the depth of the water nor will you know the condition of the road under the water.

Turn Around, Don’t Drown!

Hurricanes and Windstorms

On the island of O‘ahu, northeast trade winds prevail throughout the year generally blowing at 10-20 mph, but:

Strong gusty trades may occasionally reach 40-60 mph.
Storms approaching from the south and southeast, called “Kona Storms”, can produce hurricane strength winds.

Will a hurricane hit O‘ahu?
Since 1950 five hurricanes, or tropical storms, have caused serious damage in Hawai‘i. In 1957, Hurricane Nina produced record winds in Honolulu. O‘ahu was heavily impacted by both Hurricane ‘Iwa in 1982 and Hurricane ‘Iniki in 1992. If a Category 4 storm, like ‘Iniki, hits the islands with winds raging at 140 mph, 40% of homes could be severely damaged and another 40% could sustain minor damage.

HOW TO AVOID BECOMING A VICTIM!

Plan ahead:

Know the locations of the nearest designated hurricane shelters, usually public schools with reinforced buildings.
When a Hurricane Warning is issued, Emergency Management will announce which shelters are open.
Prepare a family plan. Note shelter locations, and telephone numbers of friends or family on other islands, or the mainland, to use as a central contact point if you become separated or local phone service is saturated.

When a hurricane or tropical storm warning is issued:

Follow instructions issued by Emergency Management and monitor radio or television for advisory, watch, and warning update information. (*See map)
If time permits, complete preparation activities. Board up windows and store loose objects.
Evacuate to the nearest shelter if you are in a low-lying coastal area, along ridge lines exposed to strong winds, in an area subject to stream flooding, or in a wooden or lightly constructed building.

If ordered to evacuate, leave immediately!

Advisory – Be Aware! An advisory highlights weather conditions that are less serious than a warning, but which could lead to conditions that might threaten life and/or property.

Watch – Prepare! A watch is used when the risk of a hazardous weather has increased significantly, but its occurrence, location, and/or timing is still uncertain.

Warning – Take Action! A warning is issued when a hazardous weather event is occurring, is imminent, or has a very high probability of occurring.

Remember: Hurricane Season in Hawai`i is June 1 – November 30. A Hurricane or Tropical Storm Warning means hurricane or tropical storm conditions are expected to occur within 36 hours. Be prepared!

Earthquakes

Over the last two centuries, the Hawaiian Islands have been struck by several destructive earthquakes. These have caused extensive damage, and triggered fatal landslides and local tsunamis. Though the most powerful earthquakes have generally occurred on the Island of Hawai‘i, O‘ahu has also been impacted by earthquakes. In 1871 a magnitude 6.8 quake centered 65 miles southeast of Honolulu, caused damage to virtually every concrete building on the island. In April of 1973 a 6.2 magnitude earthquake off Hawai‘i Island was widely felt on O‘ahu and caused minor damage. On the average two earthquakes are felt on Oahu each year, the most recent being a 4.0 magnitude trembler in 1980, a 6.7 in 2005, and a 3.5 magnitude quake in 2010.

HOW TO AVOID BECOMING A VICTIM!

Earthquakes cause destruction and loss of life by intense shaking. Knowing what to do could save your life.

If you are INDOORS during an earthquake, stay there!

Move quickly to a safe location, such as an inside corner of the room or under a strong table.
Stay away from glass, windows, outside doors, and anything that could fall.
DROP to the floor, COVER your head, HOLD ON and stay inside until the shaking stops. Most deaths and injuries occur when people inside buildings rush outside and are struck by falling debris.

If you are OUTDOORS during an earthquake, stay there!

Move to an open area away from buildings, utility lines, and trees.
If you are driving, slow down and stop on the side of the road, but not under a bridge, overpass, power lines, trees or large signs. Stay in your car.

Mountainous areas/slopes/cliffs:

Be alert for falling rocks and other debris.

Beaches:

Move quickly to higher ground or several hundred yards

inland. A local tsunami could strike.

Make sure you know what to do in an earthquake!

High Surf

In Hawai‘i, more injuries are caused by high surf than by any other coastal hazard. High surf (10-20 feet) arrives along north facing shores each winter and large waves (4-6 feet) strike south shores during summer months.

HOW TO AVOID BECOMING A VICTIM!

No matter how strong a swimmer you think you are, remember Hawai’i’s surf is among the most powerful on earth.
Large surf often generates powerful rip currents that no one can swim against.
Swim only at beaches with lifeguards on duty and always check with them about ocean conditions prior to going into the water.
Watch the surf for at least 15 minutes prior to entry in order to allow time to see a large set of waves and get a good idea of just how big the surf is.

If In Doubt, Don’t Go Out!

Wildfires

The City and County of Honolulu is at risk from wildfires. In 2010 there were over 400 wildfires on O‘ahu, and in 2009 2,385 acres burned in just 32 fire incidents. Wildfires are on the increase due to changing weather patterns bringing drier, hot weather. Development, bordering brushy forested areas, has heightened risk from wildfires. The majority of fires are caused by human negligence through discarded smoking products, sparks from equipment and power lines, campfires, careless debris burning, and arson. Wildfires are a threat to human safety and destroy precious natural resources.

HOW TO AVOID BECOMING A VICTIM!

Preventing wildfires is the single most important way to avoid becoming a victim.

Clear dry brush and other combustible materials from around your house.
Never throw lighted matches, cigarettes or other burning items on the ground or from your car.
Build campfires only in permitted areas and always have enough water to put them out.
Don’t burn refuse or debris, it adds to air pollution, and can carry sparks for long distances.

If you are camping or hiking in rural or wild country and become caught in a wildfire:

Find any kind of depression with as little flammable fuel (dry wood, brush, etc.) as possible.
Remove fuel away from the spot before the fire approaches.
Lie face down in the depression and cover yourself even if you only have sand or dirt.
Remain down on the ground until the fire has passed.
If your clothing should catch on fire: Stop, drop, and roll!