Anatomy of an Archipelago: Tectonic Forces Shaping the Philippines

A Comprehensive set of flashcards covering the tectonic forces, fault systems, and volcanic activity shaping the Philippine archipelago.

How many volcanic vents are roughly scattered across the islands of the Philippines?

There are approximately $1,350$ volcanoes throughout the country.

Where is the vast majority of geological volcanic formations concentrated in the Philippines due to tectonic collision boundaries?

They are concentrated heavily in Luzon.

What are the four distinct geological engines that drive global volcanic formation?

Island Arcs, Continental Arcs, Spreading Centers, and Hot Spots.

What specific hazard is anticipated from 'The Big One' along the Marikina Valley Fault System?

A super earthquake reaching magnitude $7.2$ or above, expected to wreak significant havoc across Metro Manila and surrounding populated regions.

Which two faults compose the Marikina Valley Fault System?

The West Valley Fault (affecting Muntinlupa, etc.) and the East Valley Fault (affecting Rodriguez, Rizal).

What occurs at a spreading center relative to mantle pressure and magma?

Plate divergence lowers mantle pressure, allowing magma to melt and rise, forming rift volcanoes.

How is a 'Hot Spot' defined in the context of volcanic formation?

Magma anomalies that burn through the moving crust, forming a trail of intraplate volcanic islands.

What are the geographic coordinates provided for the Philippine archipelago's geographic blueprint?

$$12.8797^{\circ}N, 121.7740^{\circ}E$$

How many islands make up the Philippine archipelago, and what are the three main island groups?

The archipelago is composed of $7,641$ islands divided into Luzon (North), Visayas (Central), and Mindanao (South).

What bodies of water bound the Philippines to the North, East, South, and West?

Bashi Channel (North), Philippine Sea/Pacific Ocean (East), Celebes Sea and Sulu Sea (South), and South China Sea (West).

Which fault is characterized by 'aseismic creep' (slow slide occurrences without significant earthquakes)?

The Central Philippine Fault.

Name the five major fault systems that deeply fracture the Philippine landscape.

$1.$ Western Philippine Fault, $2.$ Eastern Philippine Fault, $3.$ Central Philippine Fault, $4.$ Marikina Valley Fault System, and $5.$ Southern Mindanao Fault.

Which three massive tectonic plates collide at the 'Philippine crossroads'?

The Eurasian Plate, Indo-Australian Plate, and Philippine Plate.

What percentage of the world's active volcanoes are located in the Pacific Ring of Fire?

$75\%$ of all the world's active volcanoes.

How long ago was the Philippine archipelago formed by volcanic activities?

Approximately $50$ million years ago.

How is an 'active' volcano classified based on its eruption history?

It is in a state of frequent eruptions or has erupted within the last $10,000$ years.

Provide local examples for active, dormant, and extinct volcanoes in the Philippines.

Active: Mayon, Pinatubo, Hibok-Hibok, Taal, Bulusan, Kanlaon; Dormant: Mount Makiling; Extinct: Mount Butay in Camiguin.

What are the three geodetic tools used for millimeter-level tectonic tracking?

Global Positioning System (GPS), Very Long Baseline Interferometry (VLBI), and Satellite Laser Ranging (SLR).

At what annual speed and in what direction is the Philippine Sea Plate currently moving?

It is moving northwest at roughly $6-8\,cm$ every year.

What is the result of a subduction zone when oceanic crust meets continental crust?

The denser oceanic plate subducts and melts into magma, driving volcanic eruptions and severe earthquakes.

Which famous mountain range was formed $55$ million years ago by the convergence of the Eurasian and Indo-Australian plates?

The Himalayas.

Define the Lithosphere and the Asthenosphere.

The Lithosphere is the solid outer shell comprising the crust and upper mantle; the Asthenosphere is the weak, denser part of the upper mantle below the lithosphere whose movements drive plate shifting.

What happened at the San Andreas Fault in terms of boundary motion and plate interaction?

It is a transform boundary where the Pacific and North American tectonic plates grind alongside each other laterally.

Who proposed the hypothesis that all Earth's landmasses were once a single supercontinent called Pangaea?

Alfred Wegener.