So, the fertilizer explosion in Beirut was a surprise, and caused people to talk about other surprise explosions like the 1995 Oklahoma City fertilizer bombing of the Murrah Building, and the Halifax explosion of 1917 you probably hadn't ever learned of unless you knew some East coast Canadians (or read "Shattered City" by Kitz) but I bet no one mentioned the 5 hour long Roseville train explosions of 1973!

April 28, 1973
A 103-unit train with 21 Department of Defense freight cars originating from the Hawthorne, NV Army Depot, each carrying 330 unfused Mark 81 bombs weighing 250 pounds apiece, a total of 7,000 aircraft bombs, total of 1.75 million pounds, on its way to the Mare Island Naval Shipyard for the Vietnam War, and two large propane tanker cars exploded in a Southern Pacific railway yard, spewing flames, shrapnel and debris over a one‐square mile area and injuring at least 148 persons.

There were no immediate reports of deaths or missing persons, and the injuries to victims treated at three hospitals were described as mostly minor cuts from flying glass and debris. Four were hospitalized in “semi serious condition.” with eye injuries. Damage was estimated in the millions.

A total of 52 persons was taken to area hospitals for treatment, however, and the scene, witnesses said, resembled a war area after a bombing raid. Interstate 80, a few hundred yards from the railroad switching yard, was closed for hours and the small town of Antelope was nearly leveled by the explosions.

About 100 individual explosions occurred in a two‐hour period, but less frequent flurries of explosions, some heard 40 miles away, were still being reported more than eight hours after the first big blasts this morning.

Major blasts continued to around 1030, with smaller blasts continuing until 1605 the next day.

A railroad spokesman, Ronald Sixby said 600 other rail cars had been damaged.

Southern Pacific Railroad Co. railroad officials said the chain reaction series of blasts began at 7:52 a.m., shortly after an employee in the yard tower spotted smoke in one car of a 103-unit train which arrived about 7 a.m., and notified the yard fire department. Firemen, however, were unable to reach the scene before the first explosion.

 Mr. Sixby said the first propane car exploded a few minutes after the first explosions from within the military boxcars, “blowing fire out several hundred yards around it.”

A witness said the second propane tank car blew up a few minutes later and “threw tons of debris which looked like the siding of freight cars several hundred feet into the air. It came down smoking on wheat fields” and near homes in the area.

Hundreds of windows were broken in downtown Roseville, nearly three miles north of the center of the explosion, and broken windows were reported in other communities as far as five miles away.

The blast shook the ground in Sacremento, 15 miles away, and the dome area in the 103‐year‐old Capitol was closed to the public because the authorities feared the shock of the explosion might cause it to collapse.

https://www.facebook.com/121239447961475/posts/today-i-am-posting-the-first-five-of-over-150-photographs-taken-during-the-initi/2738143859604341/
https://www.nytimes.com/1973/04/29/archives/blast-on-train-carrying-bombs-for-navy-injures-48-on-coast.html
https://www.sacbee.com/news/local/history/article145902054.html
https://sacramento.cbslocal.com/2013/04/28/historical-society-remembers-roseville-railyard-explosions-40-years-ago/
https://oac.cdlib.org/findaid/ark:/13030/c8rr24h2/entire_text/
https://www.reddit.com/r/CatastrophicFailure/comments/b5h7t1/roseville_train_yard_explosion_1973/

NONE of that mentions the cause, the human failure related stupid actions that CAUSED this event.

Physical evidence confirmed that first explosions were centered at a DODX type boxcar loaded with 250 lb. bombs.

Further, bomb cook-off detonation tests established that the triggering bomb blast was not a result of shock loads but rather derived from an engulfing fire initiated in the boxcar wood plank floor under influence of extended heavy braking action on the mountain grade.

It was also suspected that high friction composition brake shoes were fitted on the car as replacements for cast iron shoes but the brake mechanical linkage lever ratios had not been modified as required.

https://asmedigitalcollection.asme.org/mechanicaldesign/article-abstract/113/1/91/429265/The-Roseville-Bomb-Disaster-Simulated-Train?redirectedFrom=fulltext
The American Society of Mechanical Engineers Journal of Mechanical Design


after descending from the Sierra Nevada into the Roseville Yard.

https://en.wikipedia.org/wiki/1973_Roseville_Yard_Disaster



in 1997, 8 more unexploded bombs were found buried under the rail yard.

Failure of responsibility to be enforced, and a disaster area to be thoroughly searched for what simply was found 24 years later



if you have time for one more, here is a evening news video from that day, and it's better than the above due to brevity and better video https://www.facebook.com/watch/?v=922025911294595


One hundred sixty-nine freight cars were obliterated. A diesel locomotive and 98 other freight cars were damaged. One witness, Lonnie Root, said there were bombs "laying all over the place" in the train yard and nearby fields.

 A switchman said cars were blown off the tracks on both side of the rail yard, which is 23 tracks wide. Another railroad employee said a set of wheels from a boxcar weighing more than a ton were hurled 100 feet in the air and fell near where he was working.

As an immediate consequence of the Roseville blast, spark shields above railcar wheels and non-sparking brake shoes were required.

In 1974, Furthermore, Congress passed the Transportation Safety Act, which united various regulations by different offices into one publication. Additionally, the law placed responsibility regarding shipping hazardous materials on everybody, be it the shipper, bearer or recipient.

http://www.militarymuseum.org/Roseville.html