Tectonic Plates - Science

1st topic - 1st qtr

GNSS/GPS

• Global Navigation Satellite System/Global Positioning System

• Receives timed signals from several satellites and calculates an exact ground position

• Tracks 3D movement: east-west, north-south, and up-down

• Precise movement at installed points

InSar

• Interferometric synthetic aperture radar

• Compares radar signals from satellite images taken over the same area at different times

• Maps ground movement toward or away from satellite across a wide area

• Reveals fault deformation, uplift, subsidence, and volcanic swelling

• Wide-area surface deformation

VLBI

• Very Long Baseline Interferometry

• Radio telescopes observe the same distant quasar and compare signal-arrived times

• Measures changes in the distance and direction between telescopes

• Tracks large-scale plate motion and maintains a stable global reference frame

• Global telescope-to-telescope movement

Satellite laser ranging

• Sends a laser pulse to a satellite reflector and times the returning light

• Calculates the precise distance between the station and the satellite

• Improves station positions, satellite orbits, and the global reference frame

• Precise ground-to-satellite distance seismology

Seismic Monitoring

• Seismometers record P waves, S waves, and surface waves from earthquakes and describes

• Locates earthquakes and describes their magnitude, depth, and fault motion

• Identifies active boundaries and sudden movement along faults

• Sudden earthquake and fault movement geology

Geological Evidence

• Scientists study displaced landforms, rock ages, and magnetic patterns

• Records past fault movement and long-term seafloor spreading

• Extends the evidence from decades to thousands or millions of years

• Long-term record of past movement

Tectonic plates

Large, rigid section of the Earth’s lithosphere that moves and interacts with other plates on the Earth’s surface

7 major tectonic plates

1. pacific

2. north and south america

3. africa and eurasia

4. antarctica and australia

seafloor spreading

moves outward on both sides. the closer the rock is to the mid-ocean ridge, the younger they are. progressively older as their distance from the ridge increases

seismic evidence

moves downward beneath another section

earth

dynamic planet , constantly changing due to both internal and external forces

additional info ( pls fully read )

the Earth’s geological composition, including its crust, mantle, core, and the distribution of its tectonic plates, volcanic activity, and seismic events, all contribute to the continuous and ever-changing processes that drive our planet’s dynamics

types of layers

1. compositional

2. mechanical

compositional

what its made of

layers of compositional

1. crust

2. mantle

3. core

crust

outermost, thinnest layer ( 5-70km thick ), composed of mostly silicon, oxygen, and aluminum, and makes up less than 1% of earth’s mass

continental plate

less dense, richer in silica and aluminum

oceanic plate

denser, primarily composed of iron- and magnesium-rich minerals

mantle

extends from the base of the crust to 2,900km deep, its the largest layer by volume ( 84% ) composed of silicate rocks rich in magnesium, and iron, solid but flows slowly

core

densest and hottest layer, made mostly of iron and nickel

mechanical layers

how the earth behaves

types of mechanical layers

1. lithosphere

2. asthenosphere

3. mesosphere

4. outer core

5. inner core

lithosphere

solid rigid layer that lies on top of the asthenosphere

asthenosphere

ductile region in the upper mantle capable of flowing

mesosphere

lies beneath the asthenosphere and is more rigid due to high pressure

outer core

liquid, and its motion creates earth’s magnetic field, composed mainly of liquid iron and nickel

inner core

solid, due to immense pressure despite extreme heat, and made mostly of solid iron and nickel

continental drift theory

developed by alfred wegener. proposes that the continents started out as a single landmass called Pangaea

Pangaea

supercontinent. from the greek words pan and gaea meaning “ all earth “

plate tectonic theory

scientific theory that explains the movements and interactions of earth’s lithosphere, which is divided into several large and small rigid plates known as tectonic plates

plate boundaries

region where two or more plates meet and interact

convection currents

movement of tectonic plates are primarily driven by this

slab pull

when an oceanic plate becomes dense as it cools over time. when it reaches a subduction zone, it starts to sink beneath a light plate then gravity pulls the rest of the plate along into the mantle

ridge push

happens in divergent boundaries, magma rises to form new oceanic crust. the new crust is hot and elevated, forming a mid-ocean ridge. gravity causes the elevated ridge to slide down pushing the older crust outward

types of plate boundaries

1. divergent

2. convergent

3. transform

divergent boundaries

constructive. occurs when two plates move away from each other

convergent boundaries

destructive. two plates push into eachother

oceanic-oceanic convergence

an older denser tectonic plate being forced deep into the plant underneath a younger, less dense tectonic plate

subduction

process when one of the two plates is descending beneath the other. during this, a chain of volcanoes often develop near the plate boundary

oceanic-continental convergence

subduction also occurs when an oceanic plate converges with a continental plate. it produces a trench, and a volcanic arc, series of volcanic eruptions

continental-continental convergence

subduction doesnt occur, rather collision occurs the lack of subduction leads to plates crumbling upwards, forming fold mountains

collisio

when two plates converge, they cannot submerge into the mantle due to their composition.

transform

occurs when two plates slide past eachother horizontally. results in faults and earthquakes