Volcanoes

How realistic is its physical geography in Volcano (1997)?

Introduction

Hollywood disaster movies are a popular genre of film. This article will explore the realism of the scenes shown in the film Volcano, which was produced in 1997, look into the different types of volcanoes, the formation of volcanoes, where they are usually found and will also talk about few case studies of volcanic eruptions around the world.

Volcano (1997 film)

Volcano is a 1997 disaster film directed by Mick Jackson. In the film, an earthquake breaks out in the city of Los Angeles. Minutes later, a newly formed volcano erupts from the tar pits and the lava flows down Wilshire Boulevard, melting everything in its path and also killing people in its way.

Volcanoes

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This is a diagram I drew of a composite volcano. I combined three different images together to create it, so then the volcano would be more accurate.By combining three websites together, I would've been able to show triangulation. Triangulation is when a piece of information can be backed up by two other websites, which allows it to have a higher chance of being accurate. Below are the three images I used to create the diagram above. I included aspects from all three of these so that my diagram would be more informative and detailed.

What are volcanoes?

A volcano is a mountain that opens downwards, which connects down to a magma chamber in the Earth's crust. When pressure builds up, a volcanic eruption occurs, which is when magma erupts to form lava and gases and rocks shoot out from the crater through the vents.


There are a few types of volcanoes, but the main types are shield volcanoes, cinder cone volcanoes and composite volcanoes. Volcanoes can be split into three categories: active (erupts frequently), dormant (temporarily inactive but not extinct) and extinct (never likely to erupt again).

How are volcanoes formed?

  1. Magma rises through cracks of the Earth's crust.
  2. Pressure builds up inside the Earth and the pressure is released eg. due to the movement of tectonic plates, causing an eruption.
  3. The lava from the eruption cools down and forms the new crust.
  4. Over time, after more eruptions, the rock builds up and a volcano forms.

Where do volcanoes usually form and why?

The area where volcanoes usually erupt, marked on the map on the right, is known as the Ring of Fire, which is where 60% of the world's active volcanoes lay. Active volcanoes usually occur close or on the boundaries of the tectonic plates, which are sectors of Earth's crust put together like a puzzle. These plates are not fixed in place, and are constantly moving on top of a layer of molten rock called the mantle, and sometimes, these plates accidentally slide past each other or collide against each other, causing a sudden movement, resulting in earthquakes (which causes magma to rise through the cracks of the crust and building up pressure to cause a volcanic eruption). Places where most volcanic activities occur are in the Ring of Fire, which are the geologically active zones.


Below is a map of the world with black lines separating each tectonic plate and red dots representing the volcanoes formed.

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If we compare the two pictures above, we can see that volcanoes usually occur when a plate collides with or dives under another (marked in purple). We can see that the areas marked in purple in the second photos is where most of the red dots lay in the first photo. This shows that places with convergent boundary activities cause a higher chance of volcanic eruption (the area between the Eurasian plate and the North American plate that are marked purple in the second diagram is known as the Ring of Fire in the first photo).

Volcano (1997 film) VS Reality

Geographical location of Los Angeles

Lavic Lake volcano and Amboy volcano are the two volcanoes situated in the area of Los Angeles, and they are both dormant volcanoes. Volcanoes are usually located where there is a source of magma, and usually these areas are at a plate boundary - where there are a lot of faults and earthquakes. The San Andreas Fault is an example of a place where there are lots of faults and earthquakes as plates slide past one another.


Rocks tend to melt more when one plate slide under another, and this kind of activity happens further north in Oregon and northern California, which is why there are more active volcanoes there. Los Angeles and southern parts of California might suffer from a lot of earthquakes (as it is close to the San Andreas Fault), but are not likely to be affected by volcanic eruptions as it isn't near or on any fault lines or tectonic boundary lines.


Source: http://www.laalmanac.com/geography/ge07.htm, http://www.volcanodiscovery.com/california.html

Geographical location of Mt. Nyiragongo

Mt. Nyiragongo is an active composite volcano and its main crater is about 2km wide and usually contains a lava lake. Its lava lakes had been the most voluminous and the maximum elevation of the lake has been recorded to be about 3250m.


Volcanic eruptions in the area is usually caused by the split of the Earth's crust where two parts of the African plate break apart. The area is also a volcanic hot spot, which is also responsible for the numerous amounts of eruptions. A hotspot is a region than constantly experiences volcanic activity, where lava pushes up from under the mantle to create a volcano, generally caused by rising mantle plume.


The lava from Mt. Nyiragongo is made up of melilite mephelinite, which is a type of rock rich in alkali, resulting in the lava being a fluid. By being unusually fluid and its extremely low silica content, the lava flow of Mt. Nyoragongo moves extremely fast - it could go up to 100km/hr.


Shown on the picture on the right are the African plates and fault lines. Mt. Nyiragongo is right on top of a fault line, explaining its great and constant volcanic activities.


Source: https://en.wikipedia.org/wiki/Mount_Nyiragongo

Volcanic Eruption Case Study

Volcanic eruption: Nyiragongo (Active Volcano)

Nyiragongo is an active stratovolcano located in the Democratic Republic of Congo, an area of many faults in the tectonic plates as they are constantly being stretched as they move away from each other. This particular eruption happened on 17 January 2002. A lava lake was formed in its crater and there were fissures on the south side of the volcano. The lava was approximately flowing at 60km/h, flowing straight into the city of Goma and significantly affecting the citizens living there.


Social impacts:

  • Many homes and land were destroyed by the sudden eruption of ash and lava
  • 45 people died in the first 24 hour of the eruption
  • The lava flow caused blockage of roads and stopped people from reaching particular areas in the city
  • The eruption caused the spread of cholera due to the lack of hygiene and sanitation
  • 14 villages were destroyed
  • Around 50 people were killed due to the explosion of fuel


Economical impacts:

  • 350,000 people in Goma were dependant on aid provided by other countries one month after the eruption
  • Many people lost their businesses and jobs
  • Aviation fuel stores exploded when the lava flow destroyed the airport


Environmental impacts:

  • Lava covered 15% of the city and destroyed 30% of Goma
  • If the lava had reached Lake Kivu, carbon dioxide and methane could be release from the floor of the lake


Source: http://www.bbc.co.uk/education/guides/zvnbkqt/revision/3

Analysis and Comparison between the Film and Case Study

Effect of the eruption: Film VS Case study

Volcano (1997):
  • Buildings and train stations were destroyed
  • Many people were injured and/or died
  • Traffic accidents on the roads
  • Explosions caused by lava bombs
  • Buildings, vehicles, people caught on fire due to lava bombs
  • Blockage of roads due buildings and vehicles on fire and lava flowing


Mt. Nyiragongo eruption:

The eruption of Mt. Nyiragongo caused various social, economical and environmental problems to the city of Goma. The effects include people being injured, loss of businesses and jobs, damage of land etc. A more detailed list mentioned above.


Accuracy of the effects of the eruption in the film:

It was shown pretty accurately as there were damaged buildings, train stations and severely injured people in the scenes of the eruption, but there were lava bomb and lightning in a few scenes of the eruption.


"Volcanic bombs are known to occasionally explode from internal gas pressure as they cool, but contrary to some claims in popular culture (specifically, the 1997 film Volcano), explosions are rare; in most cases most of the damage they cause is from impact, or subsequent fire damage. Bomb explosions are most often observed in 'bread-crust' type bombs." - quoted from https://en.wikipedia.org/wiki/Volcanic_bomb

How does the film differ from reality?

The film clip from Volcano (1997 film) showing the volcano eruption was extremely different from volcanic eruptions in real life. This is a scene which I took a screenshot of from the movie clip. If a volcanic eruption actually occurred in Los Angeles, the type of lava would be different than this one shown in the movie clip. The volcanic eruption would produce AA lava and the type of lava shown in the movie is thin and smooth, and definitely not AA lava.
We can see from this screenshot from the video clip that the lava is extremely thin, possibly only a few centimeters high. This rules out the possibility of being AA lava, although it doesn't make it pahoehoe lava either. Pahoehoe lava is smooth and has a "ropey" surface and is formed when lava flows slowly and if there is only a gentle slope. Due to the slow flow, pahoehoe lava also forms a skin, which hinders heat loss and makes the lava hotter than that of AA lava. The skin is what gives the lava a "ropey" surface, as the lava crumples over itself at the flow front - which clearly isn't visible in the lava in the video clip. This shows that the type of lava in the clip isn't pahoehoe lava either.

Conclusion (Summary of Comparison)

Overall, the film was unrealistic (with regards to the geographical locations of volcanic activities and types of lava):


  1. Volcanic eruptions are unlikely to happen in Los Angeles.
  2. If a volcanic eruption actually happened in Los Angeles, the type of lava would be AA lava. (A picture of AA lava shown on the right).
  3. The lava on the movie can't be classified as any type of lava - it doesn't fit the characteristics of AA lava or pahoehoe lava (the only type of lava left is pillow lava, which is pillow-shaped and are associated with underwater extrusions of lava).


Although there were a few realistic aspects to the film, including:

  1. The eruption caused chaos on the streets.
  2. People died and were injured.
  3. Homes and buildings were destroyed.
  4. Some volcanoes do spurt out hot sulphurous gas through the fumarole.


The film could be a lot more realistic if the type of lava was created so that it looked like AA lava and the setting of the film was a country that has frequent volcano activity (for example, a country close to or on a fault line so that volcanic activity happening there would be a lot more convincing).