#1 - Can you outpace an erupting volcano?
Sometimes. It depends how lava is erupted out of Earth's innards and into our lives at the surface.
Lava can slowly ooze out of a crack or crater, flowing slowly down gentle slopes at 1 or 2 miles per hour.
While I wouldn't be too keen on it heading toward my house, I would back myself to outpace lava oozing out of a volcano in this way.
I would not, however, back myself against other types of volcanic eruption.
In contrast to the oozing of a lava flow, volcanoes can violently explode, causing dense clouds of hot ash and gas to barrel away from the volcano at speeds you would struggle to match if driving a car.
An epic explosion or a soothing ooze?
Not all lava is the same! The chemical ingredients that make-up a lava vary along a spectrum, from magnesium-rich at one end to silicon-rich at the other.
Have a lot of magnesium lying round in your chemical cupboard? Your lava is more likely to be erupted as a slow-moving flow.
Surplus silicon in your stores? Your lava may prefer to explode.
It is really that simple?
Sadly not. The amount of "volatiles" (e.g., water & carbon dioxide) in a lava also influences eruption type.
Check out this soda bottle and mentos experiment. Before dropping the mentos into the bottle, the soda is calm and tranquil. Once the mentos are dropped, however, all hell breaks loose and the presenters get far more than they bargained for.
Lava is similar. Drop buckets water (instead of mentos) into a lava and it might respond with a violent outburst of ash and gas.
Ey? Eyjafjallajökull
In 2010, a small volcano in Iceland (Eyjafjallajökull) erupted, creating a huge ash cloud that disrupted air travel globally. But the eruption did not start explosively; it began as an oozing lava flow.
The initial lava flow caused a lot of ice to melt. Just like the mentos plus soda experiment, the water and lava mixture triggered an explosive eruption, with ash ejected into the atmosphere.
The air travel disruption made this volcano in Iceland famous, even if Icelanders will shake their heads at my attempt to correctly pronounce its name.
I'm standing on a volcano: what type of hazard may I face?
Just like National Archives preserve records of human activity, the rocks around you transcribe a record of previous volcanic activity.
Lets translate the rocks into an understanding of how volcanoes have previously erupted, and how they could erupt again in the future.
Check out the rocks around you: are they light or dark in color? Are they surprisingly light in weight, with lots of voids? Or are you looking at big chunks of dense rock?
As a general rule, the lighter rocks are more likely from explosive eruptions, while the darker rocks are more likely from those oozing lava flows.
Why is rock color a good indicator of lava type?
In the same way that bricks are the building blocks of walls, minerals are the building blocks of rocks, albeit A LOT smaller (generally; more on that a future edition). Minerals, like bricks, have different colors and properties.
The types of mineral present in a volcanic rock depends on the ingredients in a lava's cupboard.
A magnesium-rich cupboard will yield darker minerals like olivine and pyroxene, while those with silicon-rich stocks are better equipped to form lighter minerals like quartz and feldspar.
These minerals control the overall color of the rocks. Magnesium-rich (often oozing) lavas therefore form darker rocks, while silicon-rich (often explosive) lavas form lighter rocks.
What the Rock! What about those voids?
Those voids could mean several things, but lets assume that you are looking at a light-colored rock with lots of voids.
Just like bubbles in a soda bottle, these voids tell us that our lava was volatile rich. Combined with its light color, this suggests that these rocks could have formed from one of those terrifying avalanches of gas and dust (pyroclastic flows) that we wouldn't be able to outpace.
My rock is dark, but holey!
The rock (scoria) in your hand could have
formed by one of the most spectacular processes on Earth (IMO): a volcanic fire fountain.
These lavas sit towards the magnesium end of our lava spectrum, but have had a few mentos added to increase explosivity and create a fire fountain.
Want to see this kind-of eruption in person? Go to Stromboli, Italy! It erupts like this every 15 minutes or so!
Please note: Volcanoes are complicated. Single volcanoes can and do erupt in a variety of different ways; many of which have not been covered here. This article is designed for educational purposes and not as a "how to" during active eruptions. If you are on a seismically active volcano, please take the advice of the local authorities regarding evacuation. Stay safe.
With thanks to: Oliver Ward and Freya George for generously donating their time to provide feedback on the first draft of this article; and Morgan Kuhar for a fantastic edit to the original title.
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