The Day Vegas Shook

March 4, 2006 3:16 AM

The Day Las Vegas Shook What were you doing at 11:45am on May 4, 1988? If you were a resident of southern Nevada, you'd remember. That was the day rocket fuel factory PEPCON was wiped off the map in a series of 7 explosions, two of which measured 3.0 and 3.5 on the Richter scale. The explosions sent shockwaves across the valley, taking with it marshmellow cream from the marshmellow factory next door, denting garage doors miles away, and shattering damn near every window in Henderson. As the valley's 500,000 residents stood outside wondering what caused the explosion and the massive plume of smoke, many speculated the Russians had inexplicably attacked Henderson. Miraculously, only two people died. PEPCON never operated another day in Nevada and moved to Utah.
posted by b_thinky (37 comments total)

Seeing the video brings back memories. I remember being at school during recess, at least 30 miles away, hearing the explosion and watching the sky-high smoke plume. My older brother insists the playground was covered in marshmellow, which I don't remember. It's probably some childhood imagination/wishful thinking.

I emailed the video to my father and this was his response:

Is that the Pepcon blast in Las Vegas? If so, I do remember. I was in the office which was around Flamingo and Arville area, probably 10-15 miles from Pepcon. The ceiling tiles lifted up and fell back down and there was a boom. The same thing happened a second time. No one had any idea of what happened. Someone--I think (random guy)--said "I don't know what caused that and I don't think I want to know." We worked through the day and I found out what happened that evening when I went home.
posted by b_thinky at 3:24 AM on March 4, 2006

I was in grade school in Las Vegas at the time. I remember seeing the cloud and thinking we were being bombed. The explosion blew out the windows of my dad's office.
posted by jcruelty at 3:52 AM on March 4, 2006

marshmallow
posted by fixedgear at 3:59 AM on March 4, 2006

Now you know why people don't like to have Chernobyl anywhere near their house
posted by elpapacito at 4:24 AM on March 4, 2006

I've seen this video several times over the years and am always amazed. For me, the most striking aspect is the visible sound wave spreading across the desert floor. I've seen similar effects in videos and films of aerial bombing over Vietnam. Impressive.
posted by Thorzdad at 5:31 AM on March 4, 2006

The visible shock wave is incredible. I saw this on some Real TV episode years ago, but the sound is much better on here.

No longer do we search for an answer "what would happen if a rocket fuel plant asploded?" for indeed, it has been answered.

Amazing more people weren't killed.
posted by disillusioned at 5:35 AM on March 4, 2006

Imagine the possibilities if there was a chocolate factory and a graham cracker factory in the path of the blast?
posted by Gungho at 5:43 AM on March 4, 2006

Now you know why people don't like to have Chernobyl anywhere near their house

There's no way for Chernobyl to just randomly expode with this sort of force, short of removal of plutonium, careful machining, and, well, adding a fair amount of high explosives.

Somewhere around eight million pounds of Ammonium Perchlorate went up. Divide that by two thousand, and we have 4,000 tons of oxidizer/explosive going foom. Yes, about 4 kilotons. I don't know, offhand, the relative brisance and explosive strength between AmPerc and TNT, but I'm not that far off the mark saying that the largest explosion was on the order of 1-2 kilotons, in the classic nuclear-weapons sense.

Ammonium Perchlorate is the oxidizer used in the SRB on the Space Shuttle, burning with Aluminum as the fuel (there's also an epoxy to bind it all together, and a rubberizing compound to keep it flexible enough to avoid cracking.)

For me, the most striking aspect is the visible sound wave spreading across the desert floor

That's common with larger order detonations. The key factor is the time of the detonation -- a slow burn doesn't produce the effect, but a sharp, short detonation does. This can occur with much smaller explosion. Nuclear explosions, which are very much "sharp, short detonations" show this effect greatly.

It's caused by the compression wave compressing the atomsphere so much that it refracts the light. The nuclear double pulse is caused by the shock wave refracting the light so strongly that it blocks most of the visible light -- so you see the first flash of the detonation, that's then blocked by the shockwave, which expands, weakens, and the you see the fireball. (A double pulse is strong evidence that an explosion was nuclear -- conventional explosions, even on the kiloton range, don't explode quickly enough to produce the shockwave strength required)
posted by eriko at 5:46 AM on March 4, 2006

Thanks, b_thinky, I was just trying to find this the other day. Amazing video footage.
posted by Acey at 6:56 AM on March 4, 2006

I had never even heard of this before. That was amazing. Does anyone know if this was on par with a major volcanic eruption? Did it have an effect on the local climate that year?
posted by fossil_human at 6:59 AM on March 4, 2006

I remember Pepcon! I was in first grade. I was out at lunch recess, even all the way on the west side of town (or as far west LV had developed at the time) we heard it and saw the plume. We spent the afternoon sitting around being quiet. It was Wednesday, so we were supposed to watch Reading Rainbow that afternoon, but the CCSD closed circuit TV station was only carrying a message about turning off air conditioning units.
posted by SirOmega at 7:12 AM on March 4, 2006

Is there anyone in the room who can compare and contrast the risk posed by a plant such as the PEPCON facility with that of a liquefied Natural Gas processing and storage facility? I know, completely different animals, but my local utility is proposing to build an LNG plant/storage farm a mile from where I'm writing this, so I'm kinda interested.
posted by mojohand at 7:37 AM on March 4, 2006

Wow -- I can't believe this is not belonging to some mandatory national historical awareness. Thanks for the link!
posted by skepticallypleased at 7:52 AM on March 4, 2006

Howcome they happened to have video cameras pointed at it? Was it sort of an all-day problem?
posted by Malor at 9:01 AM on March 4, 2006

I've always blamed Danny Ocean. Were there any casino robberies that day?
posted by Astro Zombie at 9:11 AM on March 4, 2006

Wow. Impressive.

It reminds me a little of a magnesium procesing plant that caught on fire in December 2004. It was nighttime, and cloudy, so you couldn't see the smoke. Because of the magnesium, though, there was an eerie glow visible 30+ miles away on the other side of the city, and the explosions sounded like distant thunder.
posted by ubersturm at 9:16 AM on March 4, 2006

Malor: I believe that the footage you saw was filmed from on top of Black Mountain, southeast of the facility. It started as a fire that got out of hand, so someone was filming the fire and then the explosions happened as the fire got larger and compromised some storage units.
posted by SirOmega at 9:38 AM on March 4, 2006

eriko: yeah of course Chernobyl is a controlled fission reactor that couldn't explode , as far as I know an exact geometry of
timed explosions is necessary, but my point is no one want something big and dangerous near their house and not without legitimate
concerns and video proof of wtf a kiloton explosion could do.

Mojohand nailed it with Liquified Natural Gas liquid/gas converters fears ; hey that thing is rather explosive, sufficient accumulation a spark and you have a giant fuel-air bomb. For some reason I have this sensation that expensive precautions aren't top priority for profiteers so extensive inspection government inspection and control is needed.

And an insurace paid by company by reduction of profit and by gas user to cover the damage risk from explosion in the surrounding area.
posted by elpapacito at 10:11 AM on March 4, 2006

A double pulse is strong evidence that an explosion was nuclear

</put in Handy Things to Know file, along with Ctrl + Scroll to change font size.>
posted by weapons-grade pandemonium at 10:35 AM on March 4, 2006

weapons-grade pandemonium writes "put in Handy Things to Know file, along with Ctrl + Scroll to change font size."

Hopefully the second comes up more than the first.
posted by Mitheral at 10:40 AM on March 4, 2006

If you read the article, you'll see just how careless the company was.

+They let AP ooze out in the open, day and night. Once the fire got out of control, employees knew to bail because it was only minutes before the thing went boom.

+A company official later claimed the AP wasn't what caused the explosions. He said AP is not flammable. A pretty irresponsible statement that shows the company was really ignorant in terms of what they were dealing with.

+PEPCON only had $1m in insuracne, an unacceptable amount for a rocket fuel manufacturer located anywhere near civilization. The $1m wasn't even enough to replace all the windows the explosion blew out. Somehow they managed to pay for it.

The video is taken from Black Mountain. Like the rest of Las Vegas and Henderson, it looks completely different today than in 1988. Population is very dense almost all the way to Boulder City. If the accident were to take place today, consequences would be much more serious.
posted by b_thinky at 11:17 AM on March 4, 2006

mojohand asked: ...the risk posed by a plant such as the PEPCON facility with that of a liquefied Natural Gas processing and storage facility?

Many LNG accidents are listed at LNG Danger To Our Communities. They also have produced a DVD, The Risks and Danger of LNG. LNG tanks exploded at Cleveland's East Ohio Gas Company in 1944, killing 131 people and destroying several city blocks.

The Jordan Cove Retort site explains the risks of LNG transport vessels and storage facilities.
posted by cenoxo at 11:26 AM on March 4, 2006

I'm glad to see that my memories of this event were not as warped as many of my childhood memories. I've tried to make my stories more interesting so many times that some of the exaggerations I made now seem to be part of my memory. I've been saying that I saw a mushroom cloud that day for years (while thinking that it wasn't a perfect mushroom shape like the footage I've seen of nuclear blasts, but a taller one with a second plume of smoke next to it), but I'd begun to doubt myself on that account. I started watching one of the videos, and at first, I was chagrinned to see that most of the smoke was blowing out in one direction under a strong wind; not at all like my memory. Then something blew up and there was this enormous vertical plume. When the camera finally panned back, there was the mushroom cloud, just as I remembered it with the second plume of near-vertical smoke right next to it. Makes me feel a little better about my memory.

I wonder if my memory of the rest of the event was as good as that. Anyone here attending Doris French Elementary School that day? I was in the 4th grade, and I remember being in the lunch room, and as usual the room was a solid wall of noise from people talking. Then suddenly there was a loud boom and all the ceiling tiles shook and the room went dead silent. It was the quietest I'd ever heard that room (even counting weekend cub scout meetings) for about 5 seconds. I think a ceiling panel fell down here, but I'm beginning to doubt that memory now. And then all at once, everyone started talking simultaneously. That combination of silence and noise is what I think of most strongly after the mushroom cloud.

Then the fire alarm went off, and we all got very confused. We'd never had a fire drill during lunch before, and we weren't so stupid that we didn't know to go outside, but it was obviously a real emergency, and the specific route we took was not yet ingrained into our heads like it was from our classrooms. It wasn't long after that that they instituted regular fire drills during lunch. I'm surprised no one got hurt rushing out of the building. I know of one instance several years later at my sister's junior high (Woodbury) where one set of doors didn't get opened during a regular lunch hour, and the press of kids leaving the room was so bad that someone fell down and broke their arm.

When we got outside, someone must've told us that it was a factory explosion because I don't remember even thinking that it was an attack. There was smoke off in the direction of Henderson (which we were a few miles from), and then the big explosion happened. Mushroom cloud, etc. Me and my friends were convinced that there would be chemicals in the air, and so we were breathing into our shirts just in case. Most kids' parents came to pick them up. On our cul-de-sac, the windows in almost everyone's house imploded except for ours because we kept the bathroom window open a smidgeon to let the cats go in and out. It's amazing what a little pressure equalization will do.

So can anyone confirm or deny any aspects of my recall?
posted by ErWenn at 11:29 AM on March 4, 2006

eriko said: ...conventional explosions, even on the kiloton range...

Several large non-nuclear explosions have been in the 2-4 kiloton range, causing significant death and destruction.

In 1917 in Halifax, Nova Scotia (Wikipedia article), two transport ships collided in the harbour. The Mont Blanc, loaded with wartime fuel and explosives, caught fire, drifted ashore, and exploded. Some 2,000 people were killed and 1,600 buildings destroyed. Many people watching the fire from their homes were blinded by flying glass from blast-shattered windows.

The ammonium nitrate-fueled Texas City Disaster of 1947 (Wikipedia article) destroyed the port facilities and killed almost 600.
posted by cenoxo at 12:34 PM on March 4, 2006

ErWenn, I definitely remember the mushroom cloud. I was in Vail Pittman Elementary School, not too close to the explosion. Don't recall feeling or hearing the explosion, just seeing the cloud in the distance. My dad worked for the water district and his office was way closer to PEPCON. He definitely felt it!
posted by jcruelty at 12:46 PM on March 4, 2006

That is an amazing video. The only flaw is that they didn't pull back far enough to follow the shock wave. It's really fascinating how visible it is -- you can really see how the force of the explosion is in all directions, except where there's this, you know, planet -- so it spreads out along that plane.

Despite the size of the explosion, I doubt it coudl affect the climate the way tons and tons of volcanic ash in the atmosphere would -- this stuff burns up, as you can see.

Chernobyl did explode, but it wasn't a nuclear explosion. I think the best way to explain it is more like a pot boiling over and blowing its cover off: remember that nuclear plants are essentially high-tech steam engines. The Chernobyl plant didn't have a containment dome the way that Western nuke plants do; if it had it would have been a very localized disaster instead of affecting half of Europe.

There seems to be a folk understanding that mushroom clouds are only caused by nuclear explosions. The structure of the cloud (IIRC) simply relates to the mass of the explosive gas reaching upper layers of the atmosphere where there is cooler air. In fact, you can often see the condensation off of nuclear cooling towers creating a "mushroom cloud", in my experience, and there's a non-nuclear power plant that does something very similar near Kenosha, Wisconsin.
posted by dhartung at 12:48 PM on March 4, 2006

I was at Doris Hancock Elementary. I remember nothing about the event, except the vague recollection of a big black plume of smoke in the distance.

To me the amazing thing about the video is the sound. The camera is at least a few miles away, yet it visibly shakes from the soundwaves. Then you can hear the sound echoing off the mountains over and over again. LV is nearly surrounded by mountains.
posted by b_thinky at 1:42 PM on March 4, 2006

I was wondering about that echoing rumble. Crazy.
posted by jcruelty at 4:47 PM on March 4, 2006

I was at Red Rock Elementary in the fifth grade. We had all thought a teacher in the nearby room had thrown a desk as his students because he had been yelling at them all morning. When he came in to ask us what was wrong, we decided to go outside. From our place on the hill we could see a lot of smoke. Thank you for posting this!

Didn't Pepcon, under a new name, move to Utah, and blow up again?
posted by haplesschild at 5:00 PM on March 4, 2006

Cedar City, Utah, July 31, 1997 — Explosion Kills One at Chemical Factory:

A Utah fire chief calls a deadly blast at a plant that moved from Southern Nevada an accidental fluke.

A flash fire and single explosion killed one worker and critically injured another Wednesday at a chemical plant that relocated to Utah after blasts leveled its operation near Henderson nine years ago.

The 8:54 a.m. explosion occurred at Western Electrochemical Co., located in a remote area 14 miles northwest of Cedar City. The company -- the Utah operations of Las Vegas-based American Pacific Corp. -- produces ammonium perchlorate, a rocket fuel component used by the space shuttle program.

Fluke me once, shame on you. Fluke me twice...
posted by cenoxo at 6:44 PM on March 4, 2006

Wow. I hadn't heard of this before, Great links, thanks.

Given how casually PEPCON approached undustrial safety, it seems it's a miracle that hundreds more weren't killed or injured. It bothers me that the wheeelchair bound employee was abandoned by his co-workers,when the magnitude of the looming disaster became apparant.

PEPCON and it's parent company American Pacific could serve as poster boy's for corporate rapacity. A woefully underinsured company who whose lax safety procedures and shoddy storage practices inevitably resulted in disaster, they then immediately fled the state to Utah. Their attempts to shift responsibility to others were unconscionable.

I think it speaks volumes for Americans that the voters of Henderson Nevada would then subsequently elect an American Pacific corporate attorney, and the nephew of the CEO, as their Mayor.
posted by PareidoliaticBoy at 7:24 PM on March 4, 2006

I actually watched something about the forensic investigation into the cause of this explosion on Court TV earlier this week.

the most shocking thing, IMO, is that more people weren't killed.
posted by pruner at 8:49 PM on March 4, 2006

I was in 7th grade Reading class at Dell H Robison Jr High School. There was this enormous boom, and a number of the ceiling tiles fell down upon us. Our teacher thought that the teacher in the next class had done something, so she went to check. Then I think we got an announcement over the PA to stay inside and not go to our next class when the bell rang, because the school had a number of portacabin classrooms and they didn't want anyone braving the elements. We may even have been told to get under our desks, as I have a vague memory of that, though I could have invented that part. They finally cancelled the rest of the school day, after what seemed like hours to me, when they decided that the air was not so toxic that the kiddies couldn't go outside. I still had no idea what was going on, but when I finally got home, my sister, who was in high school and had been released at a reasonable time, told me what happened and we watched the footage on TV. I think it was the coolest thing I ever experienced in school, which probably says something about my schooling.

Incidentally, I wasn't in Reading because I was stupid; it was a requirement that everyone had to fulfill.
posted by Hal Mumkin at 11:32 PM on March 4, 2006

It's interesting how powerless people can be to fight fire sometimes. I was around for a titanium fire once (someone tried to cut something with heat that they ought not to have.) The firemen came, and shot all sorts of foam and chemicals at it, and then decided to just sit around until the titanium was exhausted. It attracted a news copter and made the local news.
posted by TheOnlyCoolTim at 12:20 AM on March 5, 2006

PareidoliaticBoy writes "It bothers me that the wheeelchair bound employee was abandoned by his co-workers,when the magnitude of the looming disaster became apparant. "

This is standard procedure. When an alarm sounds in the building I work in wheelchairees and others with handicaps making it impossible for them to negotiate stairs are instructed to retreat to refuge areas and wait for rescue personnel because they aren't supposed to use the elevator. The theory is that it is better to have one person killed than that person plus a half a dozen others trying to extract them from the building.
posted by Mitheral at 1:18 AM on March 5, 2006

It's not standard procedure where I work, Mitheral. We can't use the elevator, so we've been trained to use the
Evacuchair to get our wheelchair bound co-workers down the stairs.
posted by fixedgear at 3:47 AM on March 5, 2006

Yeah, assisting in the evacaution of injured and disabled coworkers is part of the drills we have in my San Francisco office building.

That is an amazing video. Watching the explosion of Mt. St. Helens from my backyard should provide similar memories for me, but for some reason I haven't a single recollection of the event (I was seven at the time).
posted by obfusciatrist at 8:01 AM on March 5, 2006