Quarter 1 - Last quiz Flashcards
The Philippines is geographically located in the ___?
Pacific Ring of Fire or also known as the circum-Pacific Belt.
This region is characterized by active volcanoes and frequent earthquakes. Its length is approximately 40,000 kilometers and borders the Pacific Ocean.
the Pacific Ring of Fire or also known as the circum-Pacific Belt.
Around __ of the world’s volcanoes, comprised of more than ___ volcanoes, are in the Pacific Ring of Fire.
75%; 450
In the Phi lippines, there are ___ active volcanoes based on the records of PHIVOLCS. These volcanoes erupted within the last ___ years.
23; 600
3 Active Volcanoes in the Philippines
- Mt. Mayon in Bicol Region
- Mt. Kanlaon in Negros Oriental
- Mt. Bulusan in Sorsogon Province
Since July 2006, this volcano has had four eruptive phases (2008, 2009, 2013, 2014), bringing the total number of historical eruptions to 52.
Mayon Volcano
This volcano had renewed volcanic activity towards the end of 2015.
Kanlaon Volcano
After 2011, this volcano had an eruptive phase occurred in May-July 2015, with more
activity in February 2016.
Bulusan Volcano
Why does the Philippines have many volcanoes?
The Philippines sits on a unique tectonic setting ideal to volcano formation. The archipelago is surrounded by subducting plates as manifested by the trenches that are related to volcano formation.
The term signifies a vent, hill, or mountain from which molten or hot rocks with gaseous materials are or have been ejected.
Volcano
The term also applies to craters, hills or mountains formed by removal of pre-existing materials of by accumulation of ejected materials.
Volcano
Is a process wherein molten rock materials are emitted or ejected in the form of flowing masses of lava or fragmental particles called pyroclastic with gas from a crater, vent or fissure.
Volcanic Eruption
PHIVOLCS Classification of volcanoes
- Active
- Inactive
- Potentially Active
A volcano is classified as active based on the following:
- if it has had eruptions in historic times supported by numerous historical accounts;
- if it has oral folkloric history which suggests an eruption that is remembered by our ancestors;
- if it has shown indications of seismic activity and
- if it has volcanic deposits less than 10,000 years as determined by radiometric dating.
A volcano is said to be inactive if ___.
it has no record of eruptions and its form has been changed by agents of weathering and erosion with the formation of deep gullies.
A volcano is said to be potentially active if ___.
it is geologically young-looking, which suggests it possibly erupted in less than 10,000 years. A volcano is said to be geomorphologically young as suggested by very little vegetation cover.
Life Cycle of Volcanoes
- Active: Has, is or showing signs that it will erupt
- Dormant: Show signs or predicted to erupt
- Extinct: Unlikely to erupt again
Types of Volcanoes
There are different types of volcanoes based on the form or
shape of their edifice, which are dependent upon the type of eruptions a volcano is capable of and ultimately the
chemical composition of the magma it erupts.
- Monogenetic cones (tuff/cones, cinder cones, maars)
- Volcanic domes/Domes complexes
- Strato-volcanoes
- Calderas
- Shield volcanoes
Classification of Magma based on Silicon Dioxide Content
- A basaltic magma is composed of the least silicon dioxide content, which is about 45 to 55%, contributes to least viscosity.
- An andesitic magma is composed of an intermediate silicon dioxide content, which is about 55-65%, contributes to a moderate viscosity
- A rhyolitic magma is composed of the highest silicon dioxide about 65 to 75%, which contributes to greatest viscosity.
- A ____ magma is composed of the least silicon dioxide content, which is about 45 to 55%, contributes to least viscosity.
Basaltic
- An ___ magma is composed of an intermediate silicon dioxide content, which is about 55-65%, contributes to a moderate viscosity.
Andesetic
- A ___ magma is composed of the highest silicon dioxide about 65 to 75%, which contributes to greatest viscosity.
Rhyolitic
Low symmetrical accumulations of cinder (scoria) and or
tuff (ash). These volcanoes are usually associated with
low silica or basaltic magma, usually for during just one
eruption, and may be lateral vents associated with
bigger volcanic complexes.
Monogenetic cones (tuff/cones, cinder cones, maars)
mound-shaped or convex volcanoes formed by repeated slow extrusion of viscous magma. Domes are associated with low- to high silica magma e.g. Hibok-hibok Volcano
Volcanic domes/ Domes complexes
