Origin of Sun, Planets & Earth History

• Natural Disasters

Origin of the Sun and Planets

• The Sun's main components are hydrogen (H) and helium (He).
• Nuclear fusion occurs when smaller hydrogen atoms fuse to create helium, converting mass into energy.

Earth History

• Earth began as an aggregating mass of particles and gases within a rotating cloud around 4.6 billion years ago.
• Key heat-generating processes during Earth's early years included impact energy, radioactive isotope decay, increasing heat that led to layer differentiation, and gravitational energy.
• The transformation of Earth was mainly due to impact energy, radioactive isotope decay, gravitational energy, and layer differentiation.
• Over a 30 to 100-million-year period, metal-rich particles (like iron-rich meteorites), rocks (like stony meteorites), and ices (water, carbon dioxide, and other compounds) accumulated to form Earth.
• As the coalescing particles enlarged, gravity pulled metallic pieces toward the center, while lighter materials concentrated near the exterior.
• Earth likely grew from random debris collisions, resulting in a somewhat homogeneous mixture.
• The substantial heat release caused widespread melting, leading to low-density materials rising to form a primitive crust of low-density rocks, large oceans, and a denser atmosphere.
• Low-density materials (magmas, waters, and gases) rose and accumulated on Earth's exterior as continents, oceans, and the atmosphere.

The Layered Earth

• The outer core is mostly liquid, and viscous convection currents generate Earth's magnetic field.
• Billions of years of volcanism helped create the continents, oceans, atmosphere, and the concentration of CHON elements (C, H, O, N), essential for life.
• Rapid stress on a material can cause brittle deformation, leading to fracture or breakage, as seen with ice.
• Prolonged stress or high temperatures can cause ductile or plastic deformation, resulting in permanent change, like chewing gum or Silly Putty.
• Stress can also cause elastic or recoverable deformation, like pulling a spring that returns to its original shape.
• Isostasy, developed in the 19th century, explains how low-density continents and mountains float on the denser mantle below, similar to an iceberg.
• The construction of Hoover Dam and the impoundment of Lake Mead caused the central region beneath the reservoir to sink up to 175 mm (7 in) over 15 years due to isostatic adjustment.

Internal Sources of Energy

• Gravitational energy was released as Earth consolidated into a denser mass, with deeper burial increasing gravitational pull and heat conversion.
• Significant heat generated during Earth's formation did not readily escape due to slow heat conduction in rocks.
• Some of this early heat still flows to the surface.
• Internal heat flow is sufficient to drive continent drift, volcanic eruptions, and earthquakes.
• Zircon crystals are crushed, dissolved in acid, and analyzed using mass spectrometry to measure uranium-238 and lead-206 amounts.
• Using these measurements and the known half-life of uranium-238, the formation time of the zircon crystal, and thus the igneous rock, can be calculated.
• Some igneous rocks are crushed to separate zircon.
• Zircon crystals contain uranium-238, locked in during magma crystallization, with virtually no lead-206 initially present.
• Lead-206 found in the crystal originates from uranium-238 decay.

Age of Earth

• The oldest Earth material ages, around 4.4 billion years, are measured from zircon sand grains in a 3.1-billion-year-old sandstone in western Australia.
• The oldest rocks on Earth, found in northwest Canada, are 4.055 billion years old and of crustal composition, suggesting recycling from even older rocks.
• The planet's age, 4.57 billion years, is determined using radioactive isotopes and their decay products collected from meteorites.
• Determining the age of Earth is challenging due to constant rock formation and destruction.

Plate Tectonics

• The tectonic cycle involves:
  • Asthenosphere rising and melting to form magma, which cools into new ocean floor/lithosphere.
  • New lithosphere slowly moving laterally from oceanic crust formation zones, known as seafloor spreading.
  • The older, colder, denser oceanic lithosphere slab colliding with another slab, turning downward, and being pulled back into the asthenosphere through subduction.
  • The remaining dense, buoyant slab overrides the other, while the pulled-in slab is reabsorbed into the mantle.
  • The cycle completion time often exceeds 250 million years.
• From a geologist-astronaut's perspective, Earth's lithosphere is broken into plates.
• The study of plate movements and interactions is known as plate tectonics.
• Movements of iron-rich fluid in Earth's outer core generate electric currents, creating the magnetic field.
• Magnetic field reversals involve the field's orientation flipping from north (normal) to south (reverse) polarity.
• Reversals take less than a thousand years, and the last occurred 780,000 years ago.
• The magnetic field becomes twisted during reversals but still protects Earth from solar and space radiation.
• Changes in the magnetic field's orientation leave imprints in rocks, which paleomagnetists can read.
• Paleomagnetic history is key evidence for seafloor spreading and has charted continental movement paths along different latitudes, providing data for a magnetic timescale.
• Lava flows accumulate as stratified rock sequences with measurable magnetic polarity. Volcanic rocks contain radioactive isotopes that enable age determination, creating a timescale of magnetic polarities when plotted vertically.
• Magma injected into oceanic ridges is imprinted by Earth's magnetic field as it cools, forming new rock.
• The seafloor/ocean crust/lithosphere is pulled away from oceanic ridges, like parts of two large conveyor belts, in opposite directions.
• The oldest ocean floor rocks are about 200 million years, less than 5% of Earth's age, while some continental rocks exceed 4 billion years.
• The oldest seafloor rocks are found at the edges of ocean basins.
• Deep-seated volumes of rock in certain locations are hotter and less dense, rising as plumes through the mantle.
• Magma rises through the lithosphere and feeds active volcanoes at hot spots forming lines of extinct volcanoes on the ocean floor, indicating plate movement direction. That hotspot also probably is responsible for the prominent bend in the island/seamount chain.
• The ocean bottom averages 3.7 km (2.3 mi) deep, with trenches exceeding 11 km (nearly 7 mi) in depth. These trenches have been understood since the 1960s.
• Trenches mark where subducting plates turn downward to re-enter the mantle.
• The progressive deepening of the seafloor with increasing age is further evidence of seafloor spreading.
• Plates slide past at transform faults or collide at convergence zones, and are constructed at divergence zones, and conserved at transform faults.
• Plate-edge interactions are directly responsible for most earthquakes, volcanic eruptions, and mountain formation.
• Evidence from paleomagnetic timescale and magnetically striped seafloors confirms seafloor spreading and plate tectonics validity.
• Lithosphere spreads, cools, and becomes denser, pulled down more strongly by gravity.
• When oceanic lithosphere collides with another plate, the denser plate goes beneath the less-dense plate in subduction.
• If an oceanic plate goes beneath another oceanic plate, it results in an island arc of volcanoes.
• If the subducting oceanic plate is pulled beneath a continent-carrying plate, the plate forms a trench, with a line of active volcanoes.
• Plate movements are outlined and have defined movement rates due to the magnetic record of seafloor rocks.

How We Understand Earth

• Uniformitarianism states that natural laws are uniform through time and space, and these laws produce consistent effects.

Summary

• Internal heat in early Earth caused widespread melting.
• Gravity layered Earth by density: heavy metallic core outward through layers of decreasing density to the atmosphere.
• The layers are in flotational equilibrium known as isostasy, and vertical land movements from isostatic adjustments are measurable.
• Radioactive isotopes heat Earth's interior at measurable rates, acting as clocks for dating events in Earth's history.
• The earth is 4.57 billion years old.
• Earth's outer layers are involved in the tectonic cycle, with hot, buoyant rock/magma rising from the mantle, building mountain ranges, via magma injection, and elevate ridges.
• Moving lithospheric plates collide where the denser rock subducts, melts, and reabsorbs.
• The lithosphere fractures into plates that diverge, slide, and converge.
• Plate collisions cause mountain formation, seafloor bending into trenches, and volcanoes.
• The evidence for plate tectonics is from ancient magnetic fields locked in rocks indicating seafloor spreading and continental drift. Ages of rocks support continuously forming and spreading oceanic crust/lithosphere, with rocks indicating recycling into the mantle.

Understanding Earthquakes

• A fault is a fracture where the two sides move past each other.

Types of Faults

• A normal fault occurs with the hanging wall moving down relative to the footwall, caused by extensional force, typical at seafloor spreading centers and areas where continents are pulled apart.
• Dip-slip faults involve major offset in the dip or vertical direction due to tension (pulling) or compression (pushing).
• With compressional forces, the hanging wall moves upward relative to the footwall, called a reverse fault, commonly found where subduction or continental collision occurs.
• When stress produces shear and causes movement along a fault to be horizontal, the fault is a strike-slip fault.
• Transform faults transfer seafloor crust forms at volcanic ridges and pulled apart by gravity and slab pull, where plates slide past each other.

Development of Seismology

• Instruments detect (seismometers) and record (seismographs) Earth motions including horizontal and vertical movements.
• A seismometer needs a stationary part to record seismic waves, accomplished by suspending a heavy mass from a frame, and Earth motions are recorded on paper or digitally.
• Earth transmits energy waves from the initial disturbance, with similarities in amplitude, wavelength, period, and frequency.
• In one second, the frequency is the number of waves passing a point, measured in hertz (Hz), where 1 Hz equals one cycle.
• Five waves/second is 5 Hz and the time between each wave is 0.2 seconds.

Seismic waves

• A fault slip or explosion releases energy as seismic waves, including body waves through the planet and surface waves.
• Primary (P) waves are body waves that are the fastest.
• Body waves ranging from about 0.02 Hz to tens of Hz produce measurable ground shaking, and are either primary or secondary waves.
• High-frequency, short-period waves are energetic close to the hypocenter/epicenter.
• P waves move in a push-pull motion and move through material depending on density and compressibility.
• Greater resistance to compression increases seismic wave speed, and the pass through packed atomic lattices.
• S waves are transverse waves that propagate by shearing or shaking particles, moving up and down perpendicular to the advancment direction.
• S waves travel through solids, with velocity being influenced by density and resistance to shearing, represented in granite at about 3 km/sec.
• S waves shake and twist the ground with side-to-side motions, causing more damage to buildings.
• Surface waves advance in a backward-rotating, elliptical motion, and put more energy into Rayleigh waves when shallower.

Rayleigh waves pass through ground and water, and have long periods, which describe earthquakes that feel like being rocked in a sea boat.

• Love waves advance with shearing motion relative to their direction, and generally travel faster than Rayleigh waves.
• Surface waves are created as Love waves and Rayleigh waves, that are referred to as L waves (long waves) with longer motion cycles are the slowest moving and carry energy greater distances.
• Motion with the L waves is similar to that of S waves, except it is from side-to-side in a horizontal plane parallel to Earth's surface.

Locating the Source of an Earthquake

• P waves travels about 1.7 times faster than S waves
• The difference in arrival times is greater between P and S waves at the earthquake origin.
• The arrival time difference for P and S waves of 11 minutes corresponds to a 8,800 km distance.
• Epicenters are located using seismograms from three stations, intersecting the circles with the distances by difference in S and P waves.
• S-P wave arrival time differences determine distance from the station to the hypocenter.
• Hypocenter surface affects surface wave timing.

Magnitude of Earthquakes

• Magnitude estimates the relative size/energy release of an earthquake and is measured from seismic wave traces with the Richter scale.
• 10-fold in the amplitude of a quake sees a increase for the earthquake (4 to 5).
• The energy released increases more rapidly.
• Seismic moment (M0) depends on fault movement, reliable measure of earthquake size and measures strain energy released by the rupture surface.
• Large earthquakes are part of a long series of movements and smaller earthquakes are foreshocks, and those that follow are aftershocks and part of that same strain on the fault.

Fault-rupture lengths and durations affect seismic waves and earthquakes with short movement lengths, as well as long distances produce greater amounts of motion. - 100 m (328 ft) rupture ≈ magnitude 4 - 1 km (0.62 mi) rupture ≈ magnitude 5 - 10 km (6.2 mi) rupture ≈ magnitude 6 - 40 km (25 mi) rupture ≈ magnitude 7 - 400 km (250 mi) rupture ≈ magnitude 8 - 1,000 km (620 mi) rupture ≈ magnitude 9

• High-frequency seismic waves die out, while low-frequency waves carry significant amounts of energy and cause a bigger impact.

Ground Motion During Earthquakes

• Buildings periods are about 0.1 second per story, The 1-story house shakes quickly, but the 30-story building sways slowly, with about 3 seconds per cycle.
• Shaking is amplified when seismic waves match the period of a building and resonance occurs buildings' periods.
• Resonance in buildings causes the collapse and catastrophic failure, also when the building is more flexible, will have a longer period.
• When shaking starts: drop, cover, and hold on.
• Buildings are designed to handle vertical forces caused by building weight and sideways and horizontal components is the biggest concern with large earthquakes.
• Usual acceleration 9.8m/sec^2, regardless of weight, it refers to .0g used in compared units and buildings shake up, down, and back, then the change can be measured as acceleration.
• The Mercalli intensity value for an earthquake depends on earthquake magnitude, distance, type of rock, building style, and duration.
• Building style is important, and buildings, bridges, and other structures fail.
• Low-frequency surface waves and the foundation are building are important and the hard rock with nearby P and S waves amplified by surface waves from earthquakes,and steep slopes fail as landslides when shaken.
• Relation on size and big quake can mean big damage and its important, closer it is to the epicenter means the most damage.
• Shaking times factor as big damages and lives lost.

Building in Earthquake Country

• Reinforce buildings to resist shaking increasing seismic for resistance a known to be retrofitting for building strength.
• The goal is building to react shaking like the body does.

Preventing Damage from Earthquakes

• Base isolation uses rubber and steel sandwiches, and more parts to resist building ground shaking and is placed on the ground or inside structure to absorb it.
• One-meter wide isolator show a wide array, while earthquakes use rubber and steel with lead to absorb energy.

How We Understand Volcanic Eruptions

• Plate tectonics and understanding is critical, Plate tectonics help understanding tectonic activity.
• Magma varieties and the magma affects an eruption with peaceful or volcanic.

Plate-Tectonic Setting of Volcanoes

• Subduction causes the volcano mountains to rise.
• The volume mag released is a spreading setting.
• the rock melting is lower with hydrated basalt.
• Rising affects continents that add plumes.

Chemical Composition of Magmas

• Rock amounts can make eruptions.
• Oxygen silicone percentage amounts high.
• Silicones dioxide creates behavior volcano.
• Silicon oxygen atoms surrounded tetrahedron charge attracting electrons
• The are ideal for location and low silicon dioxide and pressure cause magma continuing to rise .
• Liquid viscosity can be flow or slow.
• Viscosity is liquids liquid friction, or can become slow. Low is a day cream, viscosity barely.
• Silicone, oxygen and other molecules can join on a row making flow higher.

High Volcanicity Highest can be easiest in a basalt where they are on silicone so no real flow. Basalt surface magma.

• Basalt most of content crystal.

• Magma contains most dissolved water as the volcano rises and can contain around small amount of water. Crystal types. Basalt creates smaller and shallow and it is for rock by melting it melting where the amounts are more like to occur

• Rock materials are silicone levels.

• Rocks types are in layers is volatile. Where high eruptions occur, gases into old rocks and the atmosphere a pyroblastic.

How a Volcano Erupts

• Volcano erupt with heat.
• Superheats move as phases.
• Rock material lowers content and increase most.

Non-expolsive and explosive types.

• The gas volume is easy and doesn't affect explosions. Gas occurs with pybrocastic rocks.
• Explosion breaks pyroblastiv in the volume.

Air-born particles

• Air particles coarse to the volcano, as finer matter moves great distances. A air-fall deposit, and can blast across like gas flows.
• Volcano glass becomes obsidian.
• Basalt has a crust.
• And gas becomes magma it is volcanic gases filled

Viscosity can change whether blast.

• Water control to.

Geysers have water and hear a third require of surface area and boiled point.

Weather can make the air more thicker causing mudflow. Volcano makes the lava.

• Mixture contains ash and more.

• There is the power in the volcano.

• Particles fall during events by volcanic deaths. Is known the start.

• Mud makes them slide.

• Water can make secondary events or make them heavy with ice.

Japanese Tsunami, March 11 2001

• Tsunamis impacted 670 km and push at long distances.
• Were killed by tsunamis.

Tsumanis

• Subsidence can occur in some locations.
• Subsiding zones can build more.
• Japan in 2001.
• Releasing hydrogen inside ocean.
• Waves rotated by a volume
• Water rises deeper.

High wave causes it can change depth

4.5 Tsunami

Tsunami water needs calculation. Long waves move deep. A speed means 500 m sec. The waves move inside ocean depth.

Explore the origin of the sun and planets, focusing on hydrogen and helium in the sun and nuclear fusion. Learn about early Earth's formation 4.6 billion years ago, key heat-generating processes, and compositional changes due to impact energy and radioactive decay.