Brendan Canfield
Geology 1010
E Portfolio Assignment
When my teacher asked me to make an Essay on one of the geology chapters in the book. I
chose to do my essay on chapter five, which covered volcanic activity and the hazards that it presents.
Foremost, when talking about volcanoes, it is important to understand that volcanoes are one of the
most active, creative, destructive, and diverse geologic features on the earth’s crust. Studying the
structural features, location of, and types of volcanoes was very interesting and intensive to study.
There are usually three types of classifications of volcanos: shield, cinder cone, and composite.
Shield and composite volcanoes can form below the ocean and on landmasses above, while cindercones
are limited to above the surface on land. Volcanos can form summits, lagoons, new islands, extensions
of land, underwater mountains, and new layers of rock material where they are located. The most iconic
and most common volcanoes are composite volcanoes that appear around plate boundaries above subduction zones on land or underwater. These volcanoes can be the most hazardous and most complex
volcanoes of the three different types. Shield volcanoes are volcanoes where magma seeps out of the
earth and where large pillows of lava harden to make new land and are formed usually above
subduction zones. Cinder-cone volcanoes form from various sizes (but mostly small pieces) of pyroclastic
material that hardens quickly in flight and piles on top of other material that makes a steep slope at the
angle of repose.
In many cases volcanoes form new land masses, and can be made from rifts, openings in the
earths crust, and from convergent plates that are colliding and sub-ducting under one another, or from
divergent plate boundaries that are separating. There are several creative aspects of volcanoes, and
what they can do to the earth and how they melt down and cool to create mountainous terrain, new
earth, and various landforms. Volcanoes are very involved in the processing, and recycling of earth
material that is melted down and exposed to air or water that it cools it down.
Volcanoes are places where new made rock solidifies, changes in the climate occur, new volatile
gasses are released, and where seismic activity occurs. There several things that occur before an
eruption that can predict when it will erupt and how violent the eruption can be. The first distinct sign
before an eruption is the increase of seismic activity around the volcano, and the amount and
composition of gasses that are released. The next sign of an immanent eruption is an increased
temperature rise in the ground caused by the emplacement of new melted rock. Lastly and probably
the hardest sign to detect before an eruption occurs is the expansion of the near surface magma
chamber that inflates and changes the slope of the volcano. With these signs observed, recoded, and
studied closely, one can predict a near eruption in the future and can warn the population of people
that are living nearby before it comes.
Volcanic eruptions can cause a variety of disasters for people and their property. Many cities
around the world live near volcanoes and they don’t necessarily know that. There are a variety of ways
that volcanic eruptions can destroy both property and human life if people are not aware of it. The most
obvious form of destruction is the idea of pyroclastic flows going down the slopes of the volcano and
burning the hillside. This is most damaging to property and to human life, but usually the more
distressing to human life is the mixture of hot gasses and volcanic ash that is hazardous for humans to
breathe, or touch. The idea of pyroclastic debris ejected from the volcano at an explosive rate into the
air and landing on property and people is also a hazard. The volcanic ash and pyroclastic material in the
air also can cause problems for the climate as well and block out the sun, make acid rain when the
particles get into the clouds, and can destroy aircraft and automobile engines that might be nearby.
When eruptions happen and the melted flows cool, the new earth material on the surface can be rich in
minerals, and can make excellent fertilizer to promote plant life, and in turn support more lifeforms.
It is an ideal to realize volcanoes and their destructive and creative power. For many who live
nearby volcanoes, they must understand that once they see an eruption happen, they should move out
of its path and get as far away as quickly as possible to preserve their lives. As far as property goes
people must understand where their homes and property lie. Many people who live on the sides of the
volcano near the streams and down hill in valleys have the highest risk for life loss and property loss.
Volcanoes can erupt when unexpected and when they do people should only take what they can carry,
and leave their homes. To lock and safe guard their homes while they are evacuating somehow would
be a good idea but there are no guarantees that their homes will still be there or be safe to live in again
after the eruption. Should people’s homes or property be unaffected after the disaster, they can go back
after the dust and fall out settle to see their property but it is still ill advised to do so until proven
otherwise that it is safe.
When volcanic rock cools and hardens it makes new igneous rock that is rich in mineral
composition and content and can be felsic based or mafic based depending on the location of the
volcano and the minerals inside and around it.
All in all volcanoes present a fascinating subject but also a very hazardous one and one that
should not be taken lightly. It is one of the focal points when studying geology because it exposes new
rock and minerals to the atmosphere and the surface of the geosphere, where man can study new made
rock. Learning to live near volcanoes and where they are made and the risks it presents is a very
important subject to understand when knowing with what is under your feet and what man intends to
build on. From the information I learned in this chapter of geology and in the other chapters, I now have
a respect for and a wise fear of what volcanoes and what the earth can do over time. I believe that this
knowledge will help me think twice about where I visit, where I choose to live, and where I choose to
build buildings with my architecture focus in the future.