Philippines Volcanoes, Earthquakes, and Plate Tectonics: Key Concepts and Landforms

The Pacific Ring of Fire

A zone within the Pacific ocean that covers a collection of moving plate edges forming a "ring" of volcanoes that cause earthquakes.

Ring of Fire Length

40 000-kilometer, horseshoe-shaped basin associated with oceanic trenches, volcanic arcs, and plate movements.

Why Philippines has many volcanoes

Surrounded by subducting plates that provide ideal conditions for volcanic formation.

Tectonic Activity in PH

One of the most active in the world characterized by a number of volcanic activities.

What is magma

Buoyant molten rock.

What is lava

Magma that is extruded during a volcanic eruption.

Definition of Active Volcanoes

Those that erupted within the last 10 000 years.

Active Volcanoes in PH (2008 PHIVOLCS)

23 active volcanoes.

Mayon Volcano

Most active volcano in the country; located in Albay; famous for its almost perfect cone shape.

Taal Volcano

A volcanic caldera with several active volcanic landforms; a complex type of volcano.

Kanlaon Volcano

An active stratovolcano in Negros Oriental; latest activity was on June 18, 2016 (PHIVOLCS).

Bulusan Volcano

Located in Sorsogon; a stratovolcano inside a caldera; last erupted on March 2, 2017.

Potentially Active Volcanoes

Volcanoes with no historical eruption record but are morphologically young.

Inactive Volcanoes

Have not erupted for at least 10,000 years and are not expected to erupt again; morphology changed by weathering and erosion

Earthquake

Shaking of the Earth's surface due to energy release in the lithosphere

Fault

Break in Earth's crust where rocks move

Epicenter

Point on the surface directly above the earthquake's origin

Hypocenter

Exact location below ground where the earthquake starts

P-waves

Fastest seismic wave; moves through solids and liquids

S-waves

Slower wave; moves only through solids

Intensity

How strong the shaking is felt

Magnitude

Amount of energy released

Philippine Fault Zone

1,200-km fault cutting across the country

Major Trenches

Philippine Trench (East), Manila Trench, Negros Trench (West)

Other Active Faults

Marikina Fault, Legaspi Lineament, Macolod Corridor, Mindanao Fault, etc.

Strong Quake Areas

Casiguran Aurora, Ragay Gulf, Mindanao, Panay, Nueva Ecija

PH Quake History

Recorded since Spanish era; instrument data from 1892

Mountain Belts

Groups of mountain ranges that are similar in form, structure, and alignment

Mountain Formation

Formed by movements of tectonic plates

Philippine Mountain Belts

Have tropical vegetation; no alpine peaks

Most Prominent Range

Central Cordillera Mountain Range

Central Cordillera

Located in Luzon; stretches from the northern plain to Luzon Strait

Highest Peak in Luzon

Mt. Pulag - 2,922 meters; 3rd highest in the Philippines

Sierra Madre

Longest mountain range in the country; one of the oldest orogens

Caraballo Mountains

Connects Sierra Madre and Central Cordillera; headwaters of Cagayan River

Zambales Mountains

Located in western Luzon; an ophiolite formed from oceanic crust

Cabusilan Mountain Range

Mt. Pinatubo, Mount Negron, Mount Cuadrado

Kalatungan Range

Central Bukidnon; highest peak is Mount Kalatungan (2,824 meters)

Kitanglad Range

Northern Bukidnon; highest peak is Mount Dulang-dulang (2,941 meters)

Pantaron Range

Known as Central Cordillera of Mindanao; source of Mindanao, Pulangi, and Davao Rivers

Divergent boundary

What type of plate boundary forms when two plates move apart, creating rift valleys and mid-ocean ridges?

Rift valley

What landform is created when a continent stretches and its crust thins at a divergent boundary?

Oceanic-continental, oceanic-oceanic, and continental-continental

What are the three types of convergent plate boundaries?

Continental volcanic arc

What feature forms when an oceanic plate subducts beneath a continental plate?

Subduction of the denser oceanic plate

What happens during oceanic-oceanic convergence?

Transform boundary

What type of boundary occurs when two plates slide horizontally past each other (e.g., San Andreas Fault)?

San Andreas Fault

What is a famous example of a transform plate boundary?

Younger crust is found near the ridge, older farther away

How does the age of oceanic crust change with distance from a mid-ocean ridge?

Magma rises, fills the gap, and solidifies into new crust

How is a mid-oceanic ridge formed at a divergent boundary?

Collision and uplift of continental crust (e.g., Himalayas)

What occurs during continental-continental convergence?

Trenches

What deep landforms are created at subduction zones in convergent boundaries?

Volcanoes

What forms above subduction zones where magma reaches the surface?

Slab pull and ridge push

What are the driving forces behind plate movements?

281 inactive

How many inactive volcano are there?

26 Potentially active

How many potentially active?