Comprehensive Study Notes on Plate Tectonics, Geologic Hazards, and Geodetic Monitoring in the Philippines

Fundamental Earth Structure and Plate Dynamics

• Earth's interior is organized into three primary compositional layers:

  • Crust: The thin, brittle outer solid shell of the Earth.

  • Mantle: The thick, hot, ductile, plastic-like intermediate layer situated between the crust and the core.

  • Core: The extremely dense, metallic center of the planet composed predominantly of iron and nickel.

• Earth's mechanical layers govern surface tectonic movements:

  • Lithosphere: The rigid, brittle outermost mechanical shell encompassing the entire crust and the uppermost portion of the solid mantle. It is fractured into discrete, rigid sections called lithospheric or tectonic plates.

  • Asthenosphere: The semi-fluid, ductile, and plastically flowing zone of the upper mantle situated directly beneath the lithosphere upon which lithospheric plates float and move.

• Convective circulation mechanisms:

  • Heat transfer within the mantle occurs via convection currents.

  • Thermal buoyancy causes heated mantle material to rise toward the base of the lithosphere, while cooler, denser mantle material sinks.

  • These continuous convective currents act as the driving engine for lithospheric plate motions across the globe.

• Dynamic plate velocity and planetary balance:

  • Lithospheric plates move at very slow rates comparable to the growth rate of human fingernails, typically around $5\,\text{cm/year}$.

  • Because plates converge, diverge, and shear across a planet with a constant surface area, constructive processes that generate new crust are balanced globally by destructive processes that consume old crust.

Classification and Mechanics of Plate Boundaries

• Lithospheric boundaries are classified into three major tectonic categories based on their relative kinematic motions:

  • Convergent Plate Boundaries: Margins where plates move directly toward one another ($\rightarrow \leftarrow$), resulting in collision, crustal shortening, subduction, or orogeny. These are classified mechanically as destructive boundaries because lithospheric material is driven into the mantle and destroyed.

  • Divergent Plate Boundaries: Margins where plates move away from each other in opposite directions ($\leftarrow \rightarrow$), resulting in crustal extension, rifting, and seafloor spreading. These are classified mechanically as constructive boundaries because upwelling magma forms new lithospheric crust.

  • Transform Plate Boundaries: Margins where plates slide horizontally side-by-side past each other in opposite directions along strike-slip fault lines. These are classified mechanically as conservative boundaries because lithosphere is neither created nor consumed.

• Master boundary characteristics matrix:

  • Convergent Boundaries:

  • Relative Plate Motion: Towards each other (collisional or subductive).

  • Volcanic Activity: High and characterized by highly explosive eruptions (at oceanic-continental and oceanic-oceanic boundaries); completely absent at continental-continental boundaries.

  • Topographic Landforms: Deep-sea oceanic trenches, continental volcanic arcs, volcanic island arcs, and high non-volcanic fold mountain ranges.

  • Seismic Activity: Frequent, highly destructive earthquakes spanning shallow, intermediate, and deep focal depths along dipping Wadati-Benioff zones.

  • Divergent Boundaries:

  • Relative Plate Motion: Away from each other (extensional).

  • Volcanic Activity: High and characterized by effusive, non-explosive basaltic volcanism along fissures and central rifts.

  • Topographic Landforms: Mid-ocean ridges with central axial rift valleys (in oceanic domains) and continental rift valleys (in continental domains).

  • Seismic Activity: Frequent, typically mild to moderate shallow earthquakes.

  • Transform Boundaries:

  • Relative Plate Motion: Lateral horizontal sliding past each other.

  • Volcanic Activity: Virtually zero, as these boundaries lack both subduction-driven crustal melting and extensional decompression melting of the mantle.

  • Topographic Landforms: Linear fault lines, strike-slip fault scarps, and offset topographic features such as dog-leg river channels.

  • Seismic Activity: Frequent, highly concentrated shallow-focus earthquakes produced by high shear stress.

Divergent Plate Boundaries: Rifting and Crustal Genesis

• Extensional mechanics and seafloor spreading:

  • Plates pull apart under tensional tectonic forces.

  • The stretching and thinning of lithospheric material can be modeled via the "Taffy Test," where sustained pulling thins the material until it eventually fractures.

  • As tectonic plates separate, hydrostatic confining pressure on the underlying asthenosphere decreases.

  • This pressure drop induces decompression melting of mantle rock without requiring the addition of heat.

  • The generated basaltic magma rises buoyantly through lithospheric fissures, fills the separating rift gap, and cools rapidly against water or air to form solid basaltic crystalline rock.

• Chronological age distribution of oceanic crust:

  • Seafloor spreading acts as an expansive geological conveyor belt.

  • The youngest crust on the ocean floor is consistently positioned along the axial center of the mid-ocean ridge.

  • The crust progressively increases in age, thickness, and sediment accumulation with increasing lateral distance away from the spreading ridge toward continental margins.

• Oceanic vs. continental divergence:

  • Oceanic Divergent Boundaries: Characterized by extensive underwater mountain systems known as mid-ocean ridges. The Mid-Atlantic Ridge represents the longest continuous underwater mountain system on Earth, formed by the divergence of the South American Plate and African Plate in the South Atlantic, and the North American Plate and Eurasian Plate in the North Atlantic.

  • Continental Divergent Boundaries: Extensional rifting occurring on continental landmasses creates steep-walled depressions known as continental rift valleys. A prominent active laboratory for continental rifting is the Great African Rift Valley, where extensional tectonic forces are separating the Horn of Africa from the mainland continent at a rate of several centimeters per year, which will eventually flood to establish a new ocean basin.

  • Subaerial mid-ocean ridge exposure in Iceland: Iceland provides a unique geological subaerial exposure of the submarine Mid-Atlantic Ridge, where the boundary between the North American and Eurasian plates can be observed on dry land at Thingvellir.

Convergent Plate Boundaries: Subduction and Orogeny

• Subduction zone dynamics:

  • When plates of unequal density collide, the denser lithospheric plate bends and plunges downward beneath the less dense overriding plate into the asthenosphere, an interaction termed subduction.

  • The line along which subduction initiates produces a narrow, steep-sided, extremely deep marine depression known as an oceanic trench.

  • As the subducting slab descends into high-temperature, high-pressure mantle regimes, dehydration reactions release volatile fluids (primarily water) into the overlying mantle wedge, lowering the melting point of mantle peridotite and producing magma that ascends to fuel surface volcanism.

• Oceanic-Continental (O-C) Convergence:

  • Kinematics: A thin, dense oceanic plate converges with a thick, buoyant continental plate. The denser oceanic plate subducts into the asthenosphere.

  • Topographic and Geological Landforms: Forms a deep ocean trench immediately offshore parallel to the subduction front and a continental volcanic arc (chains of explosive volcanoes and mountain belts) on the overriding continental plate.

  • Primary Geological Examples: The Andes Mountains of South America formed via the subduction of the Nazca Plate beneath the South American Plate; the volcanic chains of the Philippines such as Mount Pinatubo in Central Luzon.

• Oceanic-Oceanic (O-O) Convergence:

  • Kinematics and the Density Rule: When two oceanic lithospheric plates collide, the older, colder, and structurally denser oceanic plate subducts beneath the younger, warmer, and less dense oceanic plate.

  • Physical demonstration: Modeled via the sponge collision experiment in water, illustrating that when two wet slabs meet, buoyancy differences dictate that the heavier slab is pulled down by slab-pull gravitational forces.

  • Topographic and Geological Landforms: Generates hadal-depth oceanic trenches along the plate interface and curved chains of oceanic volcanic islands termed volcanic island arcs.

  • Primary Geological Examples: The Mariana Trench (the deepest oceanic trench on the planet) formed by the subduction of the older Pacific Plate beneath the younger Mariana Plate; the Philippine Archipelago; the Japanese Archipelago.

• Continental-Continental (C-C) Convergence:

  • Kinematics: Two thick, highly buoyant continental plates collide head-on.

  • Absence of Subduction: Because both continental slabs possess low average rock densities compared to the dense mantle below, neither slab can be subducted into the asthenosphere.

  • Topographic and Geological Landforms: Massive horizontal compressional forces buckle, smash, fold, and thrust continental rocks vertically upward to form colossal fold mountain belts accompanied by crustal thickening.

  • Volcanic Absence: Complete absence of volcanic activity due to the total absence of subducting slabs and decompression pathways.

  • Primary Geological Examples: The Himalayas formed by the ongoing collision between the Indian Plate and the Eurasian Plate; the Alps in Europe.

• Ecological and agricultural implications of convergence:

  • Volcanic arcs produced by oceanic subduction erupt mineral-rich pyroclastic materials and volcanic ash.

  • This volcanic ash decomposes into mineral-dense soil that serves as a natural fertilizer, directly explaining the exceptionally high biodiversity and fertile agricultural output observed around active volcanic belts.

Transform Plate Boundaries: Lateral Shearing and Seismicity

• Kinematics of lateral motion:

  • Transform boundaries occur where lithospheric blocks slide horizontally past each other along strike-slip surfaces without perpendicular divergence or convergence.

  • Mechanical conservation: Crust is conserved—neither created nor destroyed—classifying them as conservative boundaries.

  • Stress regime: The dominant tectonic force is shear stress, which operates in opposite directions parallel to the fault trace.

• Mechanics of stick-slip friction and seismic generation:

  • Demonstrated physically through the "Jerk Demonstration" using wooden blocks or sliding books:

  • Two blocks are placed side-by-side with a continuous straight line drawn across their junction.

  • Lateral sliding causes the line to offset while preserving the surface area of both blocks.

  • Frictional resistance along the contact surfaces prevents continuous, smooth sliding, locking the blocks together in a stuck state.

  • Tectonic drive continues to apply shear stress, storing mechanical strain energy elastically within the deformed rock mass.

  • When accumulated shear stress exceeds the frictional shear strength of the fault, the rocks rupture and slip instantaneously (the "jerk"), releasing stored strain energy as high-magnitude seismic shockwaves.

• Volcanic absence along transform faults:

  • Transform boundaries feature virtually zero volcanic activity because there is no subducting lithospheric slab to melt in the mantle and no crustal separation to induce asthenospheric upwelling or decompression melting.

• Geological case studies of transform boundaries:

  • San Andreas Fault: A premier continental transform boundary in California, USA, accommodating right-lateral strike-slip motion between the Pacific Plate and the North American Plate. Offset river channels display classic "dog-leg" lateral turns across the fault trace, confirming persistent horizontal displacement.

  • Dead Sea Transform: A major strike-slip boundary in the Middle East running through Israel and Jordan, known for producing historical earthquakes that devastated ancient settlements.

  • Philippine Fault System: A continuous $1{,}200\,\text{km}$ long transform-like strike-slip fault system cutting across the Philippine Archipelago from north to south, which relieves lateral shear stresses induced by oblique plate convergence.

• Disaster Risk Reduction (DRR) for transform seismicity:

  • Transform faults generate high-risk, shallow-focus earthquakes directly beneath populated terrestrial zones.

  • Primary life-safety response: Implementation of "Drop, Cover, and Hold On" during shaking.

  • Structural engineering mitigation: Designing and constructing seismic-resistant, earthquake-ready homes and buildings.

Tectonic Framework of the Philippine Archipelago

• The Philippine Mobile Belt:

  • The Philippine archipelago is not situated on a single rigid tectonic plate; rather, it is a complex, actively deforming tectonic mosaic known as the Philippine Mobile Belt.

  • It is bounded on all sides by competing tectonic plates and opposing subduction systems, squeezed between the Sunda Plate and Eurasian Plate to the west, and the Philippine Sea Plate and Pacific Plate to the east.

  • The individual plate segments and tectonic fragments move at disparate velocities and directions, resulting in intense internal deformation.

• Flanking subduction zones and deep ocean trenches:

  • Eastern Border: Dominated by the Philippine Trench, formed by the westward subduction of the Philippine Sea Plate beneath the Philippine Mobile Belt.

  • Contains the Galathea Depth, the deepest point within the Philippine Trench, plunging to a depth exceeding $10{,}500\,\text{meters}$.

  • Western Border: Dominated by the Manila Trench, accommodating the eastward subduction of the South China Sea oceanic lithosphere beneath western Luzon.

  • Opposing subduction architecture: These opposing convergence zones drive high rates of regional seismicity, fuel active volcanic island arcs (such as Mount Pinatubo), and elevate tsunami risks for surrounding coastlines.

• The Philippine Fault Zone (PFZ):

  • A massive, continuous $1{,}200\,\text{km}$ long left-lateral strike-slip fault traversing the spine of the archipelago from Luzon through Eastern Visayas to Eastern Mindanao.

  • Accommodates the horizontal shear component of the oblique convergence between the Philippine Sea Plate and the Eurasian/Sunda margins.

  • GPS monitoring reveals significant differential velocities between blocks on opposing sides of the fault, identifying regions of high stress accumulation that culminate in major fault ruptures.

Geodetic and Satellite Monitoring Technologies

• Position vs. Velocity in crustal deformation:

  • Geodetic Position: The exact, instantaneous geographic coordinates of a fixed reference point on Earth's surface at a single moment in time.

  • Velocity: The rate of change of position over time, incorporating both speed ($\text{magnitude}$) and directional orientation ($\text{bearing}$).

  • Significance: Velocity vectors allow geophysicists to calculate the rate of tectonic strain and stress accumulation in crustal rocks adjacent to locked faults.

• Continuous Geodetic GPS Monitoring:

  • Unlike mobile handheld phones that connect to a minimum of $4$ satellites to achieve meter-level localization, geodetic GPS stations utilize high-precision antennae bolted securely into solid bedrock.

  • Measures millimeter-scale three-dimensional surface movements in real-time ($\text{velocity expressed in } \text{mm/year}$ or $\text{cm/year}$).

  • High surface velocity gradients denote rapid deformation and elevated seismic hazard; sudden coordinate shifts indicate that a fault rupture or earthquake has occurred.

  • National monitoring: Agencies such as PHIVOLCS (Philippine Institute of Volcanology and Seismology) and PAGASA maintain permanent geodetic networks across the archipelago, tracking consistent long-term coordinate drifts (such as ongoing southwestward or northwestward plate shifts observed in Davao).

• Crustal displacement vector calculations:

  • Displacement components are computed by subtracting baseline geographic coordinates from recent readings ($\Delta = \text{Coordinate}_{\text{new}} - \text{Coordinate}_{\text{old}}$). Positive differences signify displacement toward the North or East; negative differences signify displacement toward the South or West.

  • Mathematical example (Manila plate shift):

  • Measured displacement over one year: $\Delta y = 35\,\text{mm}$ North, $\Delta x = 10\,\text{mm}$ East.

  • Resultant horizontal displacement magnitude ($d$):       $d = \sqrt{(\Delta y)^2 + (\Delta x)^2} = \sqrt{35^2 + 10^2} = \sqrt{1225 + 100} = \sqrt{1325} \approx 36.4\,\text{mm}$

  • Direction of resultant displacement: North-Northeast (NNE).

• Interferometric Synthetic Aperture Radar (InSAR):

  • Physics of radar remote sensing: Spaceborne active radar sensors transmit electromagnetic radiation (radio waves and microwaves) toward the surface and record the phase and amplitude of the backscattered echo.

  • Cloud penetration: Microwaves penetrate cloud cover, rain, and darkness, making radar sensors indispensable in tropical, cloudy regions like the Philippines (operating within $7\%$ safe margins).

  • Interferogram generation: InSAR pairs two radar images of the identical geographical area captured at different times, superimposing their wave phases to create an interference pattern called an interferogram.

  • Interference fringes: The resulting interferograms feature repeating rainbow-colored fringe bands, where each full color cycle corresponds to a specific fraction of the radar wavelength, representing precise ground displacement along the satellite's line of sight.

  • The $2.8\,\text{cm}$ Fringe Metric: In many radar missions, one complete color cycle (fringe) corresponds to exactly $2.8\,\text{cm}$ of vertical ground deformation.

  • Example: An interferogram displaying $3$ concentric fringes signifies $3 \times 2.8\,\text{cm} = 8.4\,\text{cm}$ of crustal uplift or subsidence.

• InSAR Case Study: The 2013 Bohol Earthquake:

  • On October 15, 2013, a catastrophic magnitude $7.2$ earthquake struck Bohol, Central Visayas.

  • InSAR interferometric fringe mapping detected ground displacement from space, revealing a previously unmapped, blind thrust fault line running through the region near Carmen.

  • The rupture generated a prominent surface fault scarp reaching up to $3\,\text{meters}$ of vertical displacement, locally named "The Great Wall of Bohol."

  • Satellite radar data confirmed the spatial extent of the ground rupture, directly aiding PHIVOLCS in mapping structural risk.

• Open-access satellite programs: Global earth observation initiatives such as the European Copernicus Program provide open-access satellite radar datasets, enabling Filipino scientists and agencies to track volcanic inflation, fault creep, and land subsidence across the country.

• Technological complementary roles:

  • GPS provides ultra-high temporal precision at isolated, discrete bedrock stations.

  • InSAR delivers expansive spatial coverage across entire provinces, resolving continuous displacement fields and filling data gaps between GPS stations.

Marine Geophysics and Seafloor Bathymetry

• Bathymetric measurement principles:

  • Approximately $70\%$ of Earth's surface is covered by ocean water, concealing vast subduction systems and submarine volcanoes.

  • Electromagnetic radiation (light) rapidly attenuates in seawater, and deep marine environments experience crushing hydrostatic pressures, rendering optical imaging ineffective.

  • Hydroacoustics (sound) serves as the primary observational tool for mapping deep oceanic terrain.

  • Bathymetry is the science of measuring and mapping the depth and topography of ocean floors (the marine equivalent of land topography).

• Acoustic travel-time depth formula:

  • Sound travels through seawater at an average acoustic velocity of $v = 1{,}500\,\text{m/s}$.

  • Submarines and research vessels emit directed acoustic pulses ("pings") that reflect off solid seafloor features and return as echoes.

  • Because the acoustic wave travels two ways (from ship to ocean floor and back to receiver), ocean depth ($d$) is calculated using the time-of-flight equation:     $d = \frac{v \times t}{2}$     where $v = 1{,}500\,\text{m/s}$ and $t$ is the total measured two-way travel time in seconds.

• Multi-beam Sonar mapping:

  • Emits an expansive, fan-shaped swath of acoustic sound beams beneath a survey vessel rather than a single vertical pulse.

  • Simultaneously scans wide strips of the seabed, resolving complex bathymetric features into high-resolution, three-dimensional topographic maps.

  • Critical for imaging underwater trenches (such as the Manila and Philippine trenches), locating submerged volcanoes, and identifying unstable submarine slopes susceptible to mass wasting and tsunamigenic landslides.

• Fundamental ocean floor morphology:

  • Continental Shelf: The shallow, gently sloping marine extension of the continent adjacent to the coastline.

  • Abyssal Plain: The vast, flat, sediment-covered deep ocean floor situated at depths between $3{,}000\,\text{m}$ and $6{,}000\,\text{m}$.

  • Ocean Trench: Steep-walled, V-shaped longitudinal depressions marking the subduction boundary where an oceanic slab plunges into the mantle.

Geohazard Synthesis and Disaster Risk Reduction (DRRM)

• Tsunamigenic mechanics at subduction trenches:

  • Subduction zones along oceanic trenches are the primary generators of destructive tsunamis.

  • During the inter-seismic period, frictional coupling locks the subducting slab and the overriding plate together, causing the overriding plate to flex, bend, and accumulate immense elastic strain.

  • During a megathrust subduction earthquake, the locked interface suddenly ruptures, and the leading edge of the overriding plate snaps upward (coseismic seafloor uplift).

  • This vertical displacement of hundreds of square kilometers of the ocean floor instantaneously displaces the overlying water column.

  • Gravity restores the equilibrium of the water surface, radiating high-velocity ocean waves outward in all directions, which amplify in height as they approach shallow coastlines.

• Integrated geohazard mapping:

  • Effective hazard forecasting requires synthesizing disparate geophysical and geodetic datasets:

  • GPS Velocity Maps: Delineate crustal strain accumulation rates and identify locked fault segments.

  • InSAR Interferograms: Map localized ground subsidence, fault creep, slope instability, and active fault breaks.

  • Multi-beam Seafloor Sonar: Images offshore trenches and unstable underwater slopes prone to generating tsunamigenic landslides.

  • Seismic Networks: Locate hypocenters, trace Wadati-Benioff subduction geometries, and calculate focal mechanisms.

  • Combining terrestrial GPS, satellite radar, and marine sonar produces comprehensive multi-hazard risk maps for Philippine provinces.

• Disaster Risk Reduction and Management (DRRM):

  • Real-time tectonic monitoring by PHIVOLCS and PAGASA saves human lives during geologic crises.

  • Geodetic and seismic data guide Local Government Units (LGUs) in urban zoning, designing evacuation routes, and establishing designated inland "Safe Zones."

  • Offshore seismic and acoustic pressure sensors provide real-time data integration to trigger immediate coastal tsunami warnings and facilitate timely evacuations.

• Specialized scientific career pathways:

  • Geodetic Engineer: Professional tasked with measuring Earth's precise geometric shape, spatial orientation, and gravitational field; constructs and maintains national permanent geodetic GPS networks; calculates crustal velocity fields and fault strain.

  • Marine Geophysicist: Scientist who maps and investigates the structure of deep-ocean basins; deploys multi-beam sonar to delineate subsea faults and trenches; studies paleomagnetism, seafloor spreading, and tsunamigenic hazards.

Formative Assessments, Exercises, and Solutions

• Formative Assessment: Plate Tectonics and High-Tech Mapping (Session 1):

  • Question 1: What does GPS measure to track tectonic plate movement?

  • Options: A) Temperature, B) Geographic coordinates, C) Magnetic fields, D) Pressure.

  • Answer: B (Geographic coordinates).

  • Question 2: Which technology is most effective for mapping surface ground deformation across an entire province?

  • Options: A) Seismograph, B) Handheld GPS, C) Satellite Imaging / InSAR, D) Weather radar.

  • Answer: C (Satellite Imaging / InSAR).

  • Question 3: How does sonar determine the depth of the ocean floor?

  • Options: A) Brightness of reflection, B) Sound pulse travel timing, C) Water salinity variations, D) High-resolution optical cameras.

  • Answer: B (Sound pulse travel timing).

  • Question 4: A deep, V-shaped ocean trench indicates the presence of which tectonic process?

  • Options: A) Seafloor spreading, B) Subduction, C) Transform faulting, D) Continental rifting.

  • Answer: B (Subduction).

  • Question 5: Why is plate velocity data critical for disaster risk reduction?

  • Options: A) Predicts rainfall totals, B) Reveals tectonic stress buildup along faults, C) Measures Earth's core depth, D) Prevents volcanic eruptions.

  • Answer: B (Reveals tectonic stress buildup along faults).

• Formative Assessment: Radar and Satellite Remote Sensing (Session 2):

  • Question 1: What term defines tectonic plate movement per unit of time?

  • Answer: Velocity ($\text{speed and direction}$).

  • Question 2: What physical process do repeating rainbow-colored fringe bands represent on an InSAR interferogram?

  • Answer: Ground displacement / surface deformation.

  • Question 3: Complete the analogy: Bathymetry is to ocean depths as Topography is to:

  • Answer: Land elevations.

  • Question 4: Which primary Philippine government agency is tasked with monitoring national earthquakes and volcanic activity?

  • Answer: PHIVOLCS (Philippine Institute of Volcanology and Seismology).

  • Question 5: What is the primary benefit of combining satellite radar, GPS networks, and seafloor sonar?

  • Answer: Provides a comprehensive, validated multi-technology view of Earth deformation for improved public safety.

• Formative Assessment: Marine Geophysics and Bathymetry (Session 3):

  • Question 1: What is the most effective scientific instrument for mapping submerged volcanoes in the deep ocean?

  • Options: A) GPS, B) Optical Satellite, C) Sonar, D) Seismograph.

  • Answer: C (Sonar).

  • Question 2: To ensure maximum positional accuracy, permanent geodetic GPS stations must be anchored to:

  • Options: A) Dense clouds, B) Solid bedrock, C) Soil surface, D) Mobile vehicles.

  • Answer: B (Solid bedrock).

  • Question 3: Why is satellite synthetic aperture radar (InSAR) utilized extensively in the Philippines rather than visible optical cameras?

  • Options: A) Sunny climate, B) Frequent cloudy and rainy conditions, C) Constant night conditions, D) High water salinity.

  • Answer: B (Frequent cloudy and rainy conditions; radar microwaves pass through cloud cover and precipitation).

  • Question 4: What is the standard measurement unit used to report tectonic plate velocity?

  • Options: A) $\text{km/h}$, B) $\text{mm/yr}$, C) $\text{m/s}$, D) $\text{miles/day}$.

  • Answer: B ($\text{mm/yr}$).

  • Question 5: Which combined data streams are most vital for issuing rapid, accurate tsunami alerts?

  • Options: A) Sonar and seismic data, B) GPS and atmospheric pressure, C) Satellite optical and forest cover, D) Wind speed and wave direction.

  • Answer: A (Sonar and seismic data).

• Formative Assessment: Integrated Hazards and Technology (Session 4):

  • Question 1: A sudden, instantaneous shift in bedrock GPS coordinates at a station indicates:

  • Options: A) Slow plate drift, B) An earthquake, C) Seasonal temperature change, D) Battery failure.

  • Answer: B (An earthquake).

  • Question 2: Which scientific tool generates high-resolution 3D bathymetric models of the seafloor?

  • Options: A) Handheld GPS, B) Multi-beam Sonar, C) Aerial photography, D) Ground penetrating radar.

  • Answer: B (Multi-beam Sonar).

  • Question 3: High velocity vectors depicted on a crustal strain GPS map signify:

  • Options: A) Zero seismic hazard, B) High rate of tectonic deformation and stress accumulation, C) Regional sinking, D) High surface wind velocities.

  • Answer: B (High rate of tectonic deformation and stress accumulation).

  • Question 4: What is the complete technical term for the acronym InSAR?

  • Options: A) International Research, B) Interferometric Synthetic Aperture Radar, C) Internal Satellite Array, D) Instant Recording.

  • Answer: B (Interferometric Synthetic Aperture Radar).

  • Question 5: To fully assess and manage geological hazards across the Philippine archipelago, scientists must study:

  • Options: A) Only the land, B) Only the oceans, C) Both land and marine domains, D) Only the atmosphere.

  • Answer: C (Both land and marine domains).

• Formative Assessment: Convergent Boundaries (Session 1 & Session 5):

  • Question 1: Which geological feature forms when two oceanic lithospheric plates converge?

  • Options: A) Continental rift valley, B) Volcanic island arc, C) Mid-ocean ridge, D) Fold mountain range.

  • Answer: B (Volcanic island arc).

  • Question 2: What geological process occurs when a dense oceanic plate plunges beneath an overriding continental plate?

  • Options: A) Seafloor spreading, B) Subduction, C) Continental rifting, D) Shearing.

  • Answer: B (Subduction).

  • Question 3: The collision between the Indian Plate and the Eurasian Plate formed which continental mountain range?

  • Options: A) The Andes, B) The Himalayas, C) The Mid-Atlantic Ridge, D) The San Andreas.

  • Answer: B (The Himalayas).

  • Question 4: Which bathymetric depression is consistently associated with subduction zones?

  • Options: A) Axial ridge, B) Deep ocean trench, C) Abyssal plain, D) Guyot.

  • Answer: B (Deep ocean trench).

  • Question 5: Why are convergent boundaries classified as "destructive"?

  • Options: A) They pull continents apart, B) Old lithosphere is subducted into the mantle and consumed, C) They generate new ocean crust, D) They maintain constant rock mass without change.

  • Answer: B (Old lithosphere is subducted into the mantle and consumed).

  • Question 6: What tectonic feature is common to all three convergent boundary classes (O-C, O-O, C-C)?

  • Answer: Intense seismic activity (earthquakes).

  • Question 7: Which specific class of convergent plate boundary forms the deepest oceanic trenches?

  • Answer: Oceanic-Oceanic (O-O) convergence (e.g., Mariana Trench).

  • Question 8: A convergent zone characterized by massive fold mountains and intense earthquakes without volcanic eruptions represents which collision class?

  • Answer: Continental-Continental (C-C) convergence.

• Formative Assessment: Divergent Boundaries (Session 2):

  • Question 1: In what relative directions do lithospheric plates move at a divergent boundary?

  • Options: A) Toward each other, B) Away from each other, C) Lateral horizontal sliding.

  • Answer: B (Away from each other).

  • Question 2: What is the primary topographic feature produced at an oceanic divergent boundary?

  • Options: A) Ocean trench, B) Mid-ocean ridge, C) Fold mountain belt.

  • Answer: B (Mid-ocean ridge).

  • Question 3: Where is the geologically youngest crust found across an ocean basin?

  • Options: A) Along the continental shelf, B) At the axis of the mid-ocean ridge, C) In deep ocean trenches.

  • Answer: B (At the axis of the mid-ocean ridge).

  • Question 4: What topographic structure develops when a divergent boundary initiates within a continental landmass?

  • Options: A) Island arc, B) Continental rift valley, C) Folded mountain range.

  • Answer: B (Continental rift valley).

  • Question 5: Divergent plate boundaries are also classified as:

  • Options: A) Destructive boundaries, B) Conservative boundaries, C) Constructive boundaries.

  • Answer: C (Constructive boundaries; new lithospheric crust is generated).

• Formative Assessment: Transform Faults (Session 3):

  • Question 1: What is the primary kinematic motion occurring along a transform fault?

  • Options: A) Vertical subduction, B) Upwelling spreading, C) Lateral horizontal sliding, D) Head-on collision.

  • Answer: C (Lateral horizontal sliding).

  • Question 2: Which geological phenomenon is typically absent along transform boundaries?

  • Options: A) Severe earthquakes, B) Fault scarps, C) Volcanism, D) Frictional stress.

  • Answer: C (Volcanism).

  • Question 3: The San Andreas Fault in California is an example of which plate boundary class?

  • Options: A) Convergent, B) Divergent, C) Transform, D) Subduction.

  • Answer: C (Transform).

  • Question 4: Why are transform boundaries designated as "conservative"?

  • Options: A) They store seismic energy indefinitely, B) Lithosphere is neither created nor destroyed, C) They prevent major earthquakes, D) They hold continental plates together.

  • Answer: B (Lithosphere is neither created nor destroyed).

  • Question 5: What specific type of mechanical stress dominates transform plate boundaries?

  • Options: A) Compressional stress, B) Tensional stress, C) Shear stress, D) Torsional stress.

  • Answer: C (Shear stress).

• Master Review & Boundary Matching (Session 4 & Session 5):

  • Match 1: Divergent Boundary matches with Plates moving apart, forming mid-ocean ridges and continental rifts.

  • Match 2: Convergent Boundary matches with Plates colliding, causing subduction trenches, volcanic arcs, or fold mountains.

  • Match 3: Transform Boundary matches with Plates sliding past each other horizontally along strike-slip faults with no volcanism.

  • Topographic Contrast: Convergent oceanic boundaries produce deep trenches; divergent oceanic boundaries produce elevated ridges.