Boom!

Like most normal boys, I loved blowing stuff up as a young kid. Although firecrackers and bottle rockets were illegal in my locale, I had a friend that seemed to have an endless supply of them. Many a grasshopper and toy soldier (and the occasional plastic model) met its doom with the sharp pop from a firecracker or bottle rocket. 

But, unless you are holding them in your hand or next to your face, firecrackers and bottle rockets don't pose any real threat. Other explosions are different. And thus, the lead in to a few articles I came across recently that discuss really big explosions.

First up, the nuclear bomb. Cham Dallas writes at The Conversation about "What if it happened again? What we need to do to prepare for a nuclear event." He relates:

I’ve been studying the effects of nuclear events – from detonations to accidents – for over 30 years. I’ve been involved in research, teaching and humanitarian efforts in multiple expeditions to Chernobyl- and Fukushima-contaminated areas. Now I am involved in the proposal for the formation of the Nuclear Global Health Workforce.

Such a group could bring together nuclear and non-nuclear technical and health professionals for education and training, and help to meet the preparedness, coordination, collaboration and staffing requirements necessary to respond to a large-scale nuclear crisis.

Any nuclear weapon exchange or major nuclear plant meltdown will immediately lead to a global public health emergency. The Ebola outbreak taught the world that we should have resources in place to handle a major health emergency before it happens.

Looking to the Japanese bombings, he notes:

Approximately 135,000 and 64,000 people died, respectively, in Hiroshima and Nagasaki. The great majority of deaths happened in the first days after the bombings, mainly from thermal burns, severe physical injuries and radiation.

Over 90% of the doctors in nurses in Hiroshima were killed and injured, and therefore unable to assist in the response. This was largely due to the concentration of medical personnel and facilities in inner urban areas. This exact concentration exists today in the majority of American cities, and is a chilling reminder of the difficulty in medically responding to nuclear events.

What if a nuclear device were detonated in an urban area today? ... As in Hiroshima and Nagasaki, the majority of deaths would happen soon after the detonation, and the local health care response capability would be largely eradicated.

Models show that such an event in an urban area in particular will not only destroy the existing public health protections but will, most likely, make it extremely difficult to respond, recover and rehabilitate them.

With medical facilities decimated after a detonation, treating the injured will be a tremendous challenge. We would need predicted casualty distributions and locations to figure out how to best allocate what resources and personnel remain.

Very few medical personnel today have the skills or knowledge to treat the kind and the quantity of injuries a nuclear blast can cause. Health care workers would have little to no familiarity with the treatment of radiation victims. Thermal burns would require enormous resources to treat even a single patient, and a large number of patients with these injuries will overwhelm any existing medical system. There would also be a massive number of laceration injuries from the breakage of virtually all glass in a wide area.

Currently, it has not been worked out how medical systems in affected areas are supposed to cope with the overwhelming numbers of patients from an urban nuclear detonation.

 He goes on to note that response to other nuclear emergencies, Chernobyl and Fukushima for instance, required massive evacuations and resettlements of hundreds of thousands of people. But current U.S. plans do not consider large scale evacuations, primarily because the government's plans center around the detonation of a small 10 kt device.

In 2007, Dallas co-authored a paper entitled "Vulnerability of populations and the urban health care systems to nuclear weapon attack – examples from four American cities" in the International Journal of Health Geographics. From the abstract:

The effects of 20 kiloton and 550 kiloton nuclear detonations on high priority target cities are presented for New York City, Chicago, Washington D.C. and Atlanta. Thermal, blast and radiation effects are described, and affected populations are calculated using 2000 block level census data. Weapons of 100 Kts and up are primarily incendiary or radiation weapons, able to cause burns and start fires at distances greater than they can significantly damage buildings, and to poison populations through radiation injuries well downwind in the case of surface detonations. With weapons below 100 Kts, blast effects tend to be stronger than primary thermal effects from surface bursts. From the point of view of medical casualty treatment and administrative response, there is an ominous pattern where these fatalities and casualties geographically fall in relation to the location of hospital and administrative facilities. It is demonstrated that a staggering number of the main hospitals, trauma centers, and other medical assets are likely to be in the fatality plume, rendering them essentially inoperable in a crisis.

 The full paper is available at the link above, or you can download a PDF. I recommend that you read it.

On August 15, 2014, The Telegraph warned that there is a fairly high probability that a large asteroid would collide with the Earth on March 16, 2880. The article stated:

Asteroid 1950 DA has a one-in-300 chance of hitting the globe on the appointed day. Although that may sound like slim odds, it is the most likely asteroid to collide with our planet. 

... the asteroid has a diameter of one kilometre and is travelling at nine miles a second relative to the Earth. 

It is also rotating so fast - once every 2 hours and six minutes - that it "defies gravity". 

Rotation at that speed should cause the space rock to fly apart, but cohesive forces called van der Waals are holding it together. These forces have never before been detected on an asteroid.

Were it to make contact with the planet, it would hit at 38,000 miles per hour, exerting the same force as around 44,800 megatonnes of TNT. 

An impact would cause an enormous explosion and tsunamis, changing the climate of the globe and destroying human life.

 But even if you are not directly in the impact zone, an asteroid strike could still ruin your day. In a June 30, 2015, article entitled "Asteroid tsunami could kill thousands in Britain, warn scientists," The Telegraph reported:

Experts at the University of Southampton have developed software which predicts the impact ‘corridors’ of known asteroids and calculates the risk to communities if they struck. 

Although the UK is not directly under an asteroid path, it is at risk from impacts in the Atlantic Ocean and North Sea which could trigger devastating tsunamis. For example there is a one in 10,000 chance that a space rock could hit just off the coast of Norfolk within the next 85 years.

* * * 

The new maps show a wide asteroid risk zone running through Europe, passing directly over Scandanavia, Germany, France and Spain.

The US is largely unaffected, although Florida and Louisiana could be hit. South Australia is particularly at risk with several asteroid paths crossing the Lake Gairdner National Park and heading up towards Queensland. 

The asteroid impact probability distribution was also combined with the Earth population map to produce the global asteroid impact risk distribution which shows that south east Britain is one of the most at risk areas of the world. 

Dr Hugh Lewis, Senior Lecturer in Aerospace Engineering, at the University of Southampton, added: “It’s very easy to be flippant because of the Hollywood effect but it is a real risk. 

“When you look at global vulnerability Britain is at very high risk. You might think that is odd because we are a very small country but we have a high population density on the coastline so that means we are vulnerable to an impact in the Atlantic Ocean.

Danger areas in red (Source)

 Finally, "What if the Yellowstone supervolcano erupted?" The article at How Stuff Works explains:

If the Yellowstone supervolcano were to erupt, it would happen like this: Heat rising from deep within the planet's core would begin to melt the molten rock just below the ground's surface. That would create a mixture of magma, rocks, vapor, carbon dioxide and other gases. As the mix amassed and rose over thousands of years, the pressure eventually would push the ground up into a dome shape and create cracks along the edges. As that pressure was released through the cracks, the dissolved gases would explode, emptying the magma in quick fashion across the park. 

The eruption could be expected to kill as many as 90,000 people immediately and spread a 10-foot (3-meter) layer of molten ash as far as 1,000 miles (1,609 kilometers) from the park. Rescuers probably would have a tough time getting in there. The ash would block off all points of entry from the ground, and the spread of ash and gases into the atmosphere would stop most air travel, just as it did when a much smaller volcano erupted in Iceland in 2010. 

Equally as frightening is the "nuclear winter" that some experts say could blanket the U.S. and other parts of the world if Yellowstone were to blow. Sulfuric gases released from the volcano would spring into the atmosphere and mix with the planet's water vapor. The haze of gas that could drape the country wouldn't just dim the sunlight — it also would cool temperatures. Falling temperatures would do a number on our food supply, decimating crops and throwing the food chain out of whack by leaving those at the bottom with little to eat. In fact, that's what many climate scientists believe happened in C.E. 535 after a supervolcano erupted in Java.

 And the article doesn't even mention the danger from hydrochloric acid and hydroflouric acid (the latter could literally slowly dissolve the flesh of livestock and other animals left exposed to the fall out, such as after the Laki eruption in 1785). Anyway, The Daily Mail has more on the impact of a Yellowstone eruption.

Volcanic gases (source)