Volcanic Eruptions



What is a volcano?

A volcano is a sort of crack in the Earth's surface, through which molten rock, called magma, is forced out. It is like a chimney from
which, every once in a while, magma that comes from inside our planet escapes. This hot rock is found many kilometers deep and its temperature is very high (over 1000º C). At this temperature, rocks melt and form a thick "soup" with bubbles. This substance may
contain a great amount of gas. The solid surface of Earth is like a lid that has been placed to cover a pot of boiling water. The lid
prevents gases from escaping, but if this solid surface breaks, gases shoot up through the opening and spill over with magma. This
is called lava. After shooting up and flowing outward, lava cools down and turns into volcanic rock. As lava comes out, slowly or with
force, a type of smoky mountain develops: the volcanic cone. Smoke, ashes and lava come out of the top of this cone.


What is a volcanic eruption?

A volcano may or may not be active. Whenever they are active, they throw smoke or, when they explode violently, eject solid material
such as rocks, liquids and gas through a crater. A volcano is said to erupt when it ejects material and lava flows, or when it experiences
violent eruptions.


How do we know that an eruption might occur?

Volcanic activity may be watched from a nearby community:

a. Compare how the volcano has acted in previous days. If there are any changes, the volcano must be watched closely.

b. Attention must be paid to any changes experienced by fumaroles, that is, smoke holes, as well as by springs located in volcanoes;
if the weather becomes hotter, if tremors are continuous, or if there are any variations in the size of the crater hole.


What are the types of eruption?

Outpouring of mud from the crater. This mud is very hot and slides its way down slowly or quickly, depending on the hillside slope.
This represents the main cause of destruction and death produced by volcanoes.
Outburst of burning rock. Large blocks of rock can destroy houses located up to a distance of 3 kilometers from the crater.
Pyroclastic flows, which is an avalanche of incandescent material, formed by a mass of overheated gases that also includes dust,
hot ashes and lava fragments. It reaches a speed up to 160 kilometers per hour.
Acid rain. Turbid and whitish water that rains down.
Contamination of air by toxic gases.


What to do in case of a warning?

There are many observatories located near a large number of volcanoes, so that early warnings may be given. A surveillance or watch observatory is an ideal means to follow up on the volcano activity between eruption periods, so that eruptions may be anticipated. In
these observatories, vulcanologists watch volcanoes on an ongoing basis -visually of course, with different devices that are able to
detect motion signals such as trembling ground, air changes and volcanoes whose sizes change, among other things. The following is
an alert chart:

 

Levels of volcanic alerts
Type of warning
Possible term before an eruption (indicative)
Green
There is no warning
Several years
Yellow
Watch
One year (or several)
Orange
Pre-alert
Months or weeks
Red
Alert
Imminent-in progress

When there is a code red alert:

If you are outside, you must go indoors immediately and listen to the radio or watch TV to know what is happening.
You must stay indoors or go to a safer place, which has been identified previously.
If you must go out when ashes are falling, you must cover your eyes and nose with a handkerchief to be able to breathe better.
Wait for instructions from the proper authorities.
If the eruption becomes stronger, obey your parents and follow the advice of police officers, the army and vulcanologists. You
might have to abandon your house for a few days until the volcano quiets down.


What should we do before, during and after a volcanic eruption?

Previous pieces of advice:
Prepare yourself mentally to avoid situations of fear and panic.
Stay calm if a sudden eruption occurs.
Keep yourself informed about the development of this phenomenon through official authorities and scientific staff.

Before an eruption:
Have a mask or handkerchief available to cover your mouth.
Know about evacuation routes.
Cover water tanks to avoid contamination.
Protect windows, since they might break due to rock falling.
To protect yourself inside the house, bear in mind that the safest places are the interior rooms.
Cover door and window cracks with adhesive tape to prevent ash from coming inside your home.
Get away from valleys and gorges next to the volcano to avoid potential mud flows.
You must keep these items at all times: enough drinking water, nonperishable and canned food for at least 8 days, first-aid kits, water filters, paper cups and plates, flashlights and candles.

During the eruption:
Meet with your family in a safe place and pay special attention to children, elders and people with any type of medical condition.
During the eruption, stay indoors and do not go out until the atmosphere clears up.
Use a mask to breathe. You may also use towels or handkerchiefs moistened with water.
If the environment is contaminated, protect your ears and eyes.
In case a great amount of ash is falling, cars must not be driven to avoid any accident due to the ash-darkened environment.
If you are caught in the car by a rain of ashes, stay inside with doors and windows closed. If cars can be driven, this must be done slowly to avoid stirring up ashes on the ground.

After the eruption:
Keep yourself informed until authorities announce that the volcanic activity has ceased.
If sewers are clogged or river drainages blocked, stay away from these places and let the proper authorities know.
If your house is located in a risk area in terms of mudflows, go to higher lands. It is also adequate to reinforce doors, windows and vulnerable walls, so that mud cannot penetrate their construction.

 

Bibliographical References:

1. Barrios G. Javier, "Desastres Naturales: Manual para agentes comunitarios". Acción Médica Cristiana. Noviembre, 2000.
2. EIRD. "Diario de los volcanes". Costa Rica, 2002