Worst-Case Scenarios in Hawaii

Illustrations: Erik Ries

Everyone has heard the civil defense warnings, read the disaster preparation pamphlets. Yeah, sure, it’s hurricane season, what’s new? For many of us, the warnings are as easy to tune out as the flight attendant’s safety dance at the beginning of every plane trip.

But really, seriously, you should pay attention: Hawaii is uniquely situated for disasters. Many places on the Mainland might be at risk for floods and tornadoes, but not tsunamis. Or they might be threatened by earthquakes and wildfires, but not hurricanes. In Hawaii, though, we’re faced with a full menu of potential calamities. From nuclear attack to volcanic eruptions, we’re at risk for just about everything. And while it never feels this way when we’re stuck in traffic, Honolulu is literally the most isolated city in the world. When the Big One comes, there will be nowhere to run. And help may be a long time coming.

It’s scary, which is why this Halloween season, we invite you to forget about witches, vampires and zombies for a while, and think about some seriously frightening things. (And then start preparing, so you’re as ready as you can be when things inevitably go south. See 9 Tips to Prepare for a Disaster if you want to skip right to the planning tips.)


What if a Category 4 hurricane like Hurricane Iniki, which tore Kauai apart in 1992, hit Honolulu? That’s exactly the scenario Hawaii’s emergency-management officials and researchers use for disaster planning, and, after talking with them and looking at their hazard mitigation studies and plans, the answer is clear: We’d be screwed. Or as Karl Kim, a disaster researcher at UH’s Department of Urban and Regional Planning, puts it, “If Iniki had hit the south shore of Oahu, there would be potential for thousands of people to be killed, and there would be billions of dollars worth of damage.”

While Iniki-strength hurricanes come ashore with sustained winds of 131 to 155 miles per hour, wind models show Oahu’s mountainous terrain would amplify speeds to as much 200 miles per hour in some areas. A high percentage of Oahu’s wood-framed homes, most of them built to hurricane resistance standards that are no longer considered adequate, would be demolished. Roofs are always the first things to go, then walls separate and blow away and, before you know it, whole neighborhoods are flattened. Residentially developed ridgelines, exposed to some of the strongest winds, could be wiped clean.

In town, clusters of high-rises would create funnel effects that also amplify the wind. The upper floors of the tallest buildings would sway crazily, but the buildings wouldn’t fall. The lower floors would sustain the greatest damage from windborne debris. Tree branches, coconuts, two-by-fours, gravel, solar paneling and all sorts of other objects would be transformed into projectiles. Trees and power poles alike would be blown down across the island. The resulting blackout would be total and long-lasting. On Kauai, it took four months to fully restore power, water and phone service after Iniki. No one can say how long it would take on Oahu, but the job would be massive.

 Along the coast, storm surge would cause massive erosion, wash out highways and damage or destroy homes. Low-lying areas such as Waikiki and Mapunapuna would be swamped. Intense rainfall would touch off rock falls and landslides, which could damage homes and bury roads already blocked by massive amounts of debris. Streams would overflow their banks and course through neighborhoods, sweeping away loose items, like cars.

Oahu’s emergency hurricane shelters have space for about 30 percent of the island’s 1 million residents. Everybody else would be on their own. After the storm, don’t count on Safeway or Whole Foods to be there anymore, and don’t count on seeing policemen, firemen or anyone else from the government anytime soon. “You’ve got to be ready to help yourself and your family for seven days at the minimum,” says John Cummings, public information officer for the city’s Department of Emergency Services. “It’s not that we don’t want to be there, but with a population of a million people, it’s going to be a long time before you see assistance in your community.”


The tsunami evacuation maps in the front of the phone book (and online, if you’re post-phone book) represent a roughly estimated minimum for how far inland a tsunami might travel. It’s an educated guess, based upon the last century of tsunamis in Hawaii. But what if it’s a wrong guess? Suppose Honolulu got hit by a huge tsunami, the likes of which we haven’t seen in a hundred years? After all, the 2011 Japanese tsunami, which traveled as far as six miles inland, vastly exceeded anything the Japanese had planned for.

Rather than letting our darkest imagination run wild, we considered the work of Kwok Fai Cheung, a professor at UH’s Department of Ocean and Resources Engineering, who created a computer model adjusting Honolulu’s current tsunami inundation zone for rising sea levels. We appropriated his work for our dreadful purposes, assumed that the inundation zone he adjusted for one meter (3.3 feet) of sea level rise would approximate that of an extra large tsunami today, and then we let our darkest imagination run wild.

Tsunamis come ashore not as ordinary waves that break and quickly dissipate, but as rushing rivers that sweep away cars, boats, buildings and anybody unfortunate enough to get stuck in their paths. Our wave would reach more than a mile inland in places, blasting through Ala Moana Center, crashing over Kapiolani Boulevard and rushing up Keeaumoku Street past Wal-Mart. The runways at Honolulu International Airport would be submerged and undoubtedly damaged, as would docks and other facilities at Honolulu Harbor. Oil-tank farms near the waterfront would be knocked out, potentially triggering oil fires that would be spread by the waves. Sand Island would disappear underwater, and the sewage treatment plant there would wash out, contaminating the floodwaters with sewage.  

Throughout the city, light-frame construction, such as homes and warehouses, would be demolished. Steel and concrete buildings would survive, but their lower levels would be scoured of contents. Power plants along the coast at Kahe and Waiau would be destroyed, leaving the island without power indefinitely. Kakaako would be strewn with sailboats and fishing vessels from Kewalo Basin.

People would not be ready. A UH study that looked at how pedestrians in Waikiki would respond to an oncoming tsunami asked whether or not they would head for safety on the upper floors of tall buildings, as civil defense officials advise. Many would not, and the study estimated that 29 percent of Waikiki pedestrians would be killed and another 19 percent would be injured.


With nearly 8 million travelers coming and going last year, Honolulu is truly a gateway between East and West. Unfortunately, we’re also a gateway for the global transmission of diseases. Researchers at MIT recently ranked Honolulu International Airport as the third worst airport in the U.S., after New York’s and Los Angeles’, in terms of facilitating the spread of a pandemic.

To get an idea of how Honolulu might fare during an especially nasty pandemic, we turned to the 2011 movie Contagion, in which a virulent new virus, assisted by international air travel, spreads rapidly around the planet. Within days of infection, victims grow sweaty, swell up, go into convulsions, foam at the mouth and drop dead. Hospitals aren’t much help, morgues are overwhelmed and cadavers are piled into mass graves. Panic ensues and social order breaks down. There’s rioting, economic collapse, profiteering and widespread panic. The military steps in to enforce order and quarantines. Meanwhile, heroic scientists from the Centers for Disease Control race to find a vaccine. Eventually they do, the pandemic sputters out and a decimated world is left to rebuild itself.

Could this really happen? We asked Sarah Park, the Hawaii state epidemiologist, for a film review. “If you ignore some gross inaccuracies in the process of how things would work [a junior scientist would never have so much authority at the CDC as the one in the movie does] and how they portrayed the local health department [unfavorably],” Park says, “it’s not unrealistic if you’re talking about some really serious, severe pathogen that could have high mortality rates and high morbidity rates.”

That means it’s pretty realistic, right? “If you look at the big-picture concerns the movie brings up, there are definitely aspects the community can and should learn from,” Park says.

So the state epidemiologist gives Contagion a thumbs up?

“I’d give it a thumbs sideways,” she says.


When engineers and emergency planners think of a big earthquake rumbling beneath Honolulu, they think 7.0. That’s the estimated Richter scale magnitude of the biggest quake on record to strike the city, and it’s the benchmark for Honolulu’s seismic design standards. For us, it’s also the starting point for imagining what a big earthquake might do to Honolulu today.

That biggest historic quake, centered just south of Lanai, happened in 1871 at 10:11 p.m. It lasted about a minute and sent people fleeing into the streets wearing nightclothes or nothing at all. People were knocked to the ground, and the seismic waves were so intense they made some people nauseous. But there were no deaths.

The shaking set off landslides and rock falls on the Nuuanu Pali and on the cliffs behind Waimānalo. It cracked the walls of several buildings around town, including Kawaiahao Church’s. A church in Kaneohe collapsed, a belfry in Ewa toppled and every building on the campus of Punahou School was damaged.

If an earthquake of that magnitude struck Honolulu today, a long-lasting blackout would undoubtedly follow, and underground water and sewer lines could fail. As far as building damage, historic structures and older homes would get the worst of it. Walls made of unreinforced masonry, such as the brick buildings in Chinatown, could crumble. Homes built through the 1980s, before the county building code was beefed up to prevent this, could be shaken off their post-and-pier footings.

If the shaking lasted long enough, areas of loosely packed soil—such as Waikiki—could succumb to “liquefaction,” in which the ground behaves like a liquid. Roads might buckle, low-rise buildings might sink, but the high-rises—which are anchored in the underlying rock—should be able to ride out the quake without collapsing.

Bridges and overpasses, on the other hand, could come crashing down. Since 1994, the state Department of Transportation has been under a federal mandate to bring all of its bridges and overpasses up to federal earthquake standards. So far, 30 have been retrofitted on Oahu, while some 300 have yet to be assessed.



Terrorist: 100 feet /  Korean: 500 feet
The maximum size of the nuclear fireball.


Terrorist: 330 feet /  Korean: 1,990 feet
Concrete buildings are severely damaged or demolished. Fatalities approach 100 percent.


Terrorist: 670 feet /  Korean: .93 miles
Most residential buildings collapse, injuries are universal, fatalities are widespread.


Terrorist: .33 miles /  Korean: .78 miles
Without medical treatment, 50 percent to 90 percent of those exposed to this level of radiation succumb to radiation poisoning, dying within hours or weeks.


Terrorist: 560 feet /  Korean: 1.04 miles
Third-degree burns extend throughout the layers of skin, and are often painless because they destroy nerves. They can disable or cause severe scarring, and can lead to amputation.


At a morbidly fascinating website called NUKEMAP (nuclearsecrecy.com/nukemap), designed by a historian of science at the American Institute of Physics, you can detonate virtual atomic bombs anywhere on the planet to see what happens.

The biggest nuclear threat to Honolulu in 2013 is not so much from a foreign nation armed with ballistic missiles, but from a terrorist carrying a small, dirty bomb. With that in mind, and with our fingers crossed that this never comes to pass, we went to NUKEMAP, selected “crude nuclear terrorist weapon (100t),” and detonated it at the intersection of Bishop and King streets. This is the heart of Honolulu’s downtown financial district, and therefore not the most unreasonable ground zero. It also happens to be where HONOLULU Magazine’s offices are. Or were, before being flattened and engulfed by the air blast and fireball.

Just last March, North Korea—as it does from time to time—threatened to nuke Honolulu. As it’s widely believed that the North Koreans haven’t developed the missile technology to make good on these threats, nobody gets too worked up over them. Nonetheless, we plugged “North Korean weapon tested in 2013 (10kt)” into NUKEMAPS and detonated that outside our building, too. We’ve reproduced the NUKEMAP results for both bombs above.

For an even more stomach-churning nightmare—and one that’s too massive for our map to contain—go to NUKEMAP and see what happens when you detonate the Dongfeng-5, China’s big bomb, in the middle of downtown. Here’s a hint: If you’re on top of Koko Head Crater, 11 miles away, duck and cover.


Need more stuff to be worried about?  these scenarios are a lot less likely, but far from impossible.


In most land-locked areas, asteroids would have to strike relatively close to a city to do real damage. Hawaii, though, is sitting in the middle of the largest ocean on earth, and could very well be vulnerable to a large strike anywhere on the Pacific’s 63.8 million square miles. “Our understanding of tsunami physics for an event like this is still developing, but some estimates say that a 100-meter asteroid could cause tsunami waves 30 feet high upon arrival at the coast,” says Larry Dennau, a scientist for the Institute for Astronomy’s Asteroid Terrestrial-impact Last Alert System project. Luckily, these kinds of impacts only occur every few thousand years.


Hawaii’s island chain is being created by a hotspot in the Earth’s mantle that pushes magma up into a string of large shield volcanoes. But what goes up must come down. Research shows that the flank of Mauna Loa fell into the ocean about 110,000 years ago, triggering a megatsunami that pushed marine debris almost four miles inland and up 1,600 feet on the Kohala volcano. If part of Maui or Hawaii Island were to collapse today, “Probably all coastal cities and towns would be inundated, with great loss of life,” says UH School of Ocean and Earth Science and Technology professor Gary McMurtry. “Any survivors would be living in the Stone Age until help arrived from elsewhere.” He says megatsunamis occur about every 25,000 years.


Sure, tornadoes are low-probability events in Hawaii, but they might not be as low-probability as you think. More than 40 of them have been reported since 1950. The typical Hawaiian tornado begins as a waterspout, then moves ashore. The most destructive Hawaii tornado hit downtown Kailua-Kona in 1971, causing $2.5 million in damage. No deaths by tornado have ever been reported in Hawaii, but it’s entirely possible to get sucked into a funnel cloud and killed, and still more likely that fatalities could be caused by flying debris.


Africanized honey bees are virtually indistinguishable from regular honey bees except for their aggression. Though they’re illegal to bring into Hawaii, it’s possible swarms could be transported here unknowingly or smuggled in, making them a priority pest by the Hawaii Invasive Species Council. Hawaii’s year-round mild climate would make a favorable home for invasive bees, and once established, it would take very little to provoke the territorial bees, which attack en masse to defend their colonies, stinging victims dozens of times. “This bee could be devastating to beekeeping, tourism, queen bee exports and general quality of life in Hawaii,” says Danielle Downey, apiculture specialist for the Hawaii Department of Agriculture.

Oh, and just in case... Plan Z

OK, so zombies aren’t going to descend on Honolulu. Probably. We’re almost sure. But that doesn’t mean we haven’t thought about it. And if the unthinkable ever did happen, and Beretania and King streets were filled with the shuffling, moaning undead, we know exactly where we’d hole up: MAKIKI SAFEWAY! Think about it: The building is on stilts, so you’d be safely off the ground level, with only a couple of stairway access points to defend. And hey, it’s a supermarket, fully stocked with all the food, medicine and booze you’d need to stay alive and happy until the cavalry arrived. Let the hardcore survivalist types run for the back of Palolo Valley—we’re gonna stay where the beer is.

More: 9 Tips to Prepare for a Disaster