Hurricanes, Earthquakes, Tsunamis, and Floods in Hawaii

If you are living in or visiting Hawaii, it is important to know how to prepare and what to do if a hurricane, earthquake, tsunami, or flood occurs.

By REAL. Updated Jul 29, 2022. | Living in Hawaii | 8 min. read

Hurricanes in Hawaii

Hawaiian hurricanes typically form in the Pacific Ocean. Hurricane season in Hawaii is roughly from between June 1 and November 30 each year. Hawaii typically experiences about four or five tropical cyclones each year; although during the 2015 hurricane season, Hawaii had around fifteen tropical cyclones.

When was the last hurricane in Hawaii?

In July 2020, Hurricane Douglas passed north of Hawaii, bringing heavy rain and strong winds to all the islands. While the hurricane once seemed to be targeting directly at the North Shore of Oahu, it passed slightly north, causing minimal damage to the islands. This was the closest hurricane to Oahu recorded in history.

Since historical records of hurricanes or tropical cyclones in Hawaii were recorded in 1949, at least 29 people have died. The deadliest tropical cyclone to hit Hawaii was Hurricane Iniki in 1992, which killed 6 people and caused $3.1 billion in damage, much of which was on the island of Kauai.

How can I prepare for a hurricane in Hawaii?

Make sure you have a way to get information through the local news on TV, the Internet, or radio. You can also sign up for local emergency notification systems. The City & County of Honolulu as well as Hawaii, Kauai, and Maui and the entire state have emergency notification sites, which can send automatic messages if you sign up.

For hurricanes, tropical storms, and other natural disasters, it is important to prepare, especially because of Hawaii’s isolation as an island. The State of Hawaii, Office of Public Health Preparedness, recommends the following:

Tsunamis in Hawaii

A tsunami is a series of giant waves from that ocean, often caused by earthquakes, underwater landslides, volcanic eruptions, or asteroids. Tsunamis can travel around 20 to 30 miles per hour and can reach heights of 100 feet. Tsunamis can cause major flooding and also disrupt transportation, power, communication, and water supplies.

What is the history of tsunamis in Hawaii?

Since 1812, there have been a total of 135 confirmed tsunamis in Hawaii, according to the International Tsunami Information Center from the United Nations.

The worst tsunami in Hawaii, in terms of damage and deaths, occurred in 1946. An 8.6 magnitude earthquake off the coast of Alaska created a 16-foot-tall tsunami that created $150 million in damage (2016 dollars). There were 158 deaths: 121 on Hawaii Island (96 in Hilo), 17 on Kauai, 14 on Maui and 6 on Oahu.

How can I prepare for a tsunami in Hawaii?

If you are living or visiting Hawaii, it is not uncommon for a tsunami warning to happen almost every year. Therefore, it is important to prepare ahead of time the best that you can.

Floods in Hawaii

In Hawaii, everyone lives in a flood zone. Floods in Hawaii happen from both the ocean and the mountain sides. The oceans will rise with the tides, including king tides, which are abnormally high tides due to the moon, causing flooding to nearby houses. Ocean swells with large waves also can produce flooding, especially during Hawaii winters. Rivers that transgress the mountains and flow to the ocean also can flood when the rains pour.

Hawaii homeowners should also note that homes in Hawaii have flood designations, which may require flood insurance to be purchased if you have a mortgage. The State of Hawaii Department of Land and Natural Resources (DLNR) manages the Hawaii flood designations.

Here are the Hawaii flood zones for properties:

What were some significant Hawaii floods?

On Oahu, most people will remember the October 2004 flood in Manoa. Intense rains caused the Manoa stream to overflow, and a bridge was clogged by debris in the river, creating a flood wave through residential Manoa areas and into the University of Hawaii at Manoa campus. The total damage was estimated at around $85 million with about 120 homes sustaining damage.

On the Big Island or Hawaii Island, one of the worst floods was recorded in November 2000, when rains and thunderstorms were fierce for more than 24 hours. Nearly 300 homes were destroyed or damaged and roads, bridges, and other infrastructure was destroyed, creating limited options to exit the town of Hilo and Pahala.

One of the worst floods in all the Hawaiian Islands in recent history occurred on Kauai and Oahu in April 1974. Severe storms created over $3.7 million in property damage, with the worst damage happening in the Haleiwa, Mapunapuna, and Fort Shafter neighborhoods. Hundred of vehicles and thousands of agricultural crops were destroyed. Four people died during this flood, including an infant.

How can I prepare for a flood in Hawaii?

If you are under a flood warning, it is important to find a safe shelter and evacuate if told to do so. Do not try to walk or drive through floods, as fast-moving water has a history of danger in Hawaii. Before the flood occurs, there are a number of preventative steps you can take:

Earthquakes in Hawaii

All of the sudden the ground shakes rapidly; this is an earthquake. Hawaii is at a higher risk for earthquakes than other states in the United States; in fact, thousands of earthquakes occur every year in Hawaii, mostly due to the moving magma from Hawaii’s active volcanoes: Kilauea, Mauna Loa, Hualalai, Haleakala, and Loihi.

Hawaii also sometimes experiences tectonic earthquakes at the cross-section of Hawaii Island’s Kilauea Volcano’s south flank. The third type of earthquake that occurs in Hawaii is a mantle earthquake, in which the Earth’s crust and upper mantle bends due to the weight of the islands above.

What were the worst earthquakes in Hawaii?

Hawaii earthquake history includes a magnitude 7.9 quake in 1868 that struck the Ka‘u district of the Big Island and claimed 77 lives. Landslides as a result of the earthquake caused 31 casualties, and a tsunami from the earthquake claimed 46 lives.

The most recent fatal earthquake was a 7.2 magnitude quake, also on Hawaii Island, in 1975. This earthquake generated a tsunami that was as high as 47 feet on Hawaii Island. It caused the death of two people and around 28 injuries.

How can I prepare for an earthquake in Hawaii?

Preparing for an earthquake in Hawaii is important to do before it happens. Here are some important items to prepare for a Hawaii earthquake:

If an earthquake suddenly occurs, realize the best action for your location:

Natural Disasters and Hawaii Home Ownership: Important Information

Natural disasters do occur in Hawaii, and it is important to be prepared, especially since Hawaii is an isolated island away from other potential resources. For more information, read this comprehensive, Hawaii-specific guide from the University of Hawaii to prepare for all types of natural disasters, the Homeowner’s Handbook to Prepare for Natural Hazards.

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