Earth Science Exam 2
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224 terms
Terms | Definitions |
|---|---|
 What is an earthquake | Vibrations (waves) produced by sudden energy releases within the earth |
| Elastic rebound theory | Stress - applied on either side of a fault Strain (bending) - begins to build up Rupture (breakage) - Strain is greater than the rock's internal strength (break) |
| Focus | The underground location where breaking rocks generate an earthquake |
| Epicenter | The earth's surface directly above the focus |
| Rebound | the rock snap back, which generates wave energy called an earthquake |
| Fault | large cracks in the earth that have measurable movement |
| Normal fault | One side moves down as it pulled by gravity. Prevail tension |
| Reverse Fault | one side of the fault moves over the other side. Prevail compression |
| Thrust Fault | low angle reverse fault (less than 45 degrees) |
| Strike slip faults | lateral slip faults |
| Right lateral slip fault | objects on the other side of the fault move to the right |
| Left lateral slip fault | objects on the other side of the fault move to the left |
| Active Fault | a fault that has broken the earth's surface within the last 11,000 years |
| measuring waves using a seismograph | recording drum to record.drum attached to the earth drum shakes. pen attached to hanging weight inertia |
| Body waves | they move through the body of the earth |
| P waves (primary waves) body waves | push-pull or compression waves travel through solid, liquids, and gases they bounce back when released Fastest waves |
| S Waves (secondary waves) body waves | transverse or side to side waves move at the right angles to the direction of travel transmit only though solids Second fastest waves |
| Surface waves | S waves that move side to side (Love waves) and up and down (Raleigh waves) Most destructive waves. least fastest waves have the strongest shaking. |
| Ritchter scale magnitude | measure the wave amplitude (maximum pen movement on seismogram on log 10 graph |
| One Richter magnitude height of wave | is a 10 times increase in wave height/amplitude of s waves |
| One Richter magnitude in shaking energy | is a 32 times increase in shaking energy |
| Seismic hazards: destruction form earthquakes | Shaking hazards Landslide hazards liquefaction hazards surface faulting hazards Tsunami hazards |
| Shaking hazards | STRUCTURE DAMAGE shaking intensity duration of shaking site geology design of structure FIRE |
| Landslide hazards | Upland Hazards: seismic energy (shaking) applies to weak natural slopes or over-weighed slopes (by poor construction design) |
| Liquefaction hazards | Flatland hazards especially near-coastal regions and rivers |
| Surface faulting hazards (ground rupture) | Active fault no building for human occupancy within 50 feet of identified active faults |
| Tsunami Hazards | Seismic sea waves (no tidal waves) |
| how tsunami hazard form | Large movement along a fault on the ocean floor large landslides on ocean floor |
| What are the first warnings of a Tsunami | Rapid withdrawal of water form beaches five to thirty minutes later large surge of water washes onto the beach and inland water retreats back out to sea (most destructive phase) ten to sixty minutes later, next pulse of water comes ashore |
| Layered earth theory * based on seismic model | Crust - solid Upper Mantle - solid Asthenosphere - plastic Lower Mantle - solid D layer - plastic Outer Core - liquid inner core - solid |
| Seismic waves move fastest | in cold rocks |
| Seismic waves move slower | in hot rocks |
| Which is the lightest density | Crust |
| Which is the heaviest density | Inner Core |
| Layered earth theory * based on heat flow | Crust - insulator Upper mantle - convection currents Asthenosphere - partial melting (plastic) Lower mantle - convection currents "D" Layer - Partialy melting (plastic) Outer core - convection currents Inner core - radioactive decay releases heat (specially uranium) |
| How does the plates of the earth's crust move | Plates of the earth's crust move as coherent, solid units with respect to each other |
| Plate boundaries/plate margins | are where plates of crust meet |
| how does Rigid plates move | move on soft asthenosphere |
| Divergent plate margins | where plates move apart, resulting in upwelling of magma from the mantel, cools to form new seafloor rock |
| What is the process of forming new seafloor rock called | sea floor spreading |
| Mid ocean ridge | continuous ridge formed by rising molten mantle, cools on the ocean floor and moves away form the spreading center |
| Rift Valleys | When spreading center develop below continents hot rising "Mantle plume" weakens continental rocks and pulls continents apart by extensional forces |
| Rift Valleys | Red sea Gulf of Baja California Atlantic ocean |
| Convergent Plate Margins | zones of plate convergence, where oceanic lithosphere is subducted and absorbed into the mantle |
| Subduction zone | region where oceanic plate descends into the mantel |
| Deep ocean trench | the ocean floor feature produced over a subduction zone |
| Types of convergent boundaries | Oceanic-continental convergence Oceanic Oceanic convergence Continental continental convergence |
| Oceanic continental convergence | The thicker, less dense continental crust "floats" over the descending thinner and denser oceanic crust melts at 100 km to 150 depth Newly formed magma rises to form either lines of volcanoes or lines of plutonic mountains |
| Oceanic continental convergence | Examples Andean ranges Cascade ranges Japanese archipelago |
| Oceanic Oceanic convergence | when two oceanic plates converge, the colder, older, denser plate descends under the younger, warmer, lighter plate |
| Oceanic Oceanic convergence | Example Aleutian islands |
| continental continental convergence | Neither plate will subduct beneath the other because of the low density, buoyant nature of continental rocks |
| Continental continental convergence | Example Himalaya mountains |
| Transform plate boundaries | plates grind past each other without production or destruction of lithosphere |
| Transform fault | in the same level of the fracture zone |
| Driving mechanism theories | Convection current hypothesis Slab pull and slab push hypothesis Mantle plume hypothesis |
| Convection current hypothesis | Large convection currents in mantle carry lithosphere in a conveyor belt |
| Slab pull and slab push hypothesis | as oceanic slabs cool, they become denser and heavier. dense heavy slabs pull down into subduction zones |
| Mantle plume hypothesis | All upward convection is confined to a few mantle plumes. dense cool slab is drawn down into subduction zone by gravity |
| Proofs of plate tectonic theory | Polar Wandering Magnetic reversals Earthquake patterns Ocean drilling Hot spots |
| Polar wandering | Iron-rich grains in older rocks do not align with present magnetic poles on earth, continent must have moved |
| Magnetic reversals | seafloor spreading: magnetic field periodically reverses its polarity. observed in reversal strips on side of mid ocean ridges |
| Earthquake patterns | close association between plate boundaries and distribution of earthquakes |
| Ocean drilling | Age of ocean sediment increased with increasing distance from mid ocean ridges |
| Hot spots | mantle plumes age of chains of submerged volcanoes (seamounts) increase away form presently active volcanoes |
| Hot Spots | Example Hawaiian islands |
| Dissolved Gases | important in volcanic erruption |
| Gas bubbles form | pressure is released as magma moves upward toward the surface |
| Magma composition | Especially silica |
| silicate chains | make the magma more viscous (thicker texture) |
| Low viscosity | fluids flow readily |
| high viscosity | fluids are highly resistant to flow |
| Magma viscosity | affects ability of gas bubbles to reach the surface |
| Basalts | Very fluid lavas, quit volcanic eruptions |
| Rhyolites | very viscous lavas, very violent eruptions |
| Magma temperature | Higher magma temperature results in less viscous lava |
| Basalt | Hotter lavas 1200 degrees makes smooth lavas |
| Basalt | Hawaiian basalts |
| Volcanic eruptions | dissolved gasses magma composition magma temperature pressure |
| what is extruded during volcanic eruptions | Lava flows Rhyolite flows |
| Basalt flows | pahoehoe flows aa flows |
| Pahoehoe flows | Hawaiian smaller bubbles very fluid |
| aa flows | rough jagged blocks form as gas escapes form lava |
| Rhyolite flows | Very viscous, bubbly flows |
| Gases | magmas are 1 to 5 percent gases - especially water |
| Pyroclastic materials | Ash: fine, sand-size cinders: pea-size lapilli: walnut-size blocks: larger than lapilli |
| is rhyolite lighter or heavier than basalt | lighter |
| is basalt ligher or heavier than rhyolite | heavier |
| Shield volcanoes | Basalt only |
| Typically basaltic composition | very fluid flows |
| Basalt is silica | poor hot |
| cinder cones | rhyolite mostly (some basalt) |
| composite volcanoes | lava flows - cinders Andesite |
| Mt Shasta & Mt Lassen | Steep majestic mountains; typically andesite composition |
| Nuee Ardent | ash flows-fast moving, glowing HOT avalanches-often air-rafted |
| Lahar | water-saturated volcanic ash and vocalic debris COLD |
| Calderas | volcanic collapse structures |
| size of caldera | a volcanic crater greater than 1 kilometer in diameter |
| Caldera form | when a partially emptied magma chamber collapses |
| Larger calderas form | when granitic magma chambers are close to ground surface and the roof collapses |
| Examples of calderas | Yellowstone Long Valley, CA |
| Lava Plateaus | Extensive fluid basalt flows form fissures eruptions |
| Examples of Lava Plateaus | Snake River plain Columbia river Plateau Earth's Moon |
| Volcanic necks | erosional remnants of cinder cones |
| Cinder covering | eroded away form cinder cones |
| Example of cinder covering | East Mojave Desert |
| Intrusive igneous structures | Plutons |
| Plutons | Underground igneous rocks classified according to shape and size |
| Plutons | Dikes and Sills Laccolths and Batholiths |
| Dikes | Vertical-sheet |
| when are vertical dikes produced | when magma is injected into fractures that cut across rocks layers |
| Sills | Horizontal tabular flat pluton |
| When are horizontal sills formed | when magma is injected along sedimentary bedding surfaces |
| Laccolith | Larger, lens-shaped pluton which arches overlying strata upward |
| When do Laccolith form | when the magma was forcibly injected |
| Batholith | the largest intrusive igneous bodies |
| What is the size of Batholith | greater than 64 square kilometers |
| How do rocks melt | temperature pressure (sudden release of pressure) role of volatiles |
| Temperature | Geothermal Gradient Rising heat form mantle Crust is an insulator |
| Geothermal Gradient | It gets hotter as you go deeper 20 to 30 degrees / kilometer about 1 degree F/100 feet, per book |
| Pressure | increases with depth |
| Melting | result in increase in volume, volume is held constant at depth, requires higher temperature at depth |
| Sudden release of pressure | lower a rock's melting temperature |
| Role of volatiles | very difficult to melt dry rock |
| in order for rocks to melt you need | water |
| what does volatiles cause | rock to melt at lower temperatures |
| Sloder Flux example | Flux removes impurities Flux absorbs and concentrates heat Volatiles add vapor pressure |
| partial melting | The spark plug |
| Rocks typically melt | over a range of 200 degrees C |
| Minerals with the lowest melting points | Melt first (example quartz) |
| As temperature rises Silica | sweats out of crystal structures |
| Partial melting tends to produce a magma that | has a higher silica content than the original rock |
| Distribution of igneous Activity | spreading centers subduction zones Intraplate Igneous Activity |
| Subduction Zone | Basalt becomes contaminated with silica rich continental rocks |
| intraplate igneous activity | Mantle plumes |
| Isostasy | Less dense crust Floats |
| Oceanic crust is | denser than continental crust |
| Isostatic adjustment | The crust process at funding a new level of equilibrium |
| Isostatic adjustment | added weight removal weight erosion slowly reduce mountains |
| Rock deformation | forces greater than rock strength |
| Types of deformation | Elastic deformation Plastic deformation stress Strain Strike Dip |
| Elastic deformation | reversible rocks first stretch up to elastic limit like rubber band |
| Plastic deformation | past elastic limit flowing and folding permanent changes occur |
| Stress | force per unit area |
| strain | change in shape or size in response to stress |
| Compressive stress | results in rock being flattened |
| tensional stress | result in rock bending stretched |
| shear stress | stress parallel to a plane in opposite direction |
| Strike | compass direction of a line formed by intersection at horizontal and dipping planes |
| Dip | horizontal plan and incline plane |
| Folds | result of compressional forces |
| Anticlines and synclines | two most common folds |
| Anticlines formed | by up-folding or arching |
| Anticlines | oldest sediments are inside at the core of the fold youngest sediments outside |
| Syncline formed | by down warping into troughs |
| Syncline | youngest sediments are inside at the core of the fold oldest sediments outside |
| Example of syncline | Irvine valley |
| Domes | produced by up-warping old rocks are in the center |
| Domes shape | like a circular anticline or a double ended doubly planing anticline |
| Basins | produced by down-warping youngest rocks are in the center |
| Basins shape | like a circular syncline or a double ended doubly plunging syncline |
| Faults | fractures where appreciable movement has occurred |
| Dip slip faults movement | is mostly vertical |
| Hanging wall | Rock above the fault surface |
| Foot wall | rock below the fault surface |
| Normal Fault | hanging wall moves downward |
| reverse fault | hanging wall moves upward against gravity |
| thrust fault | reverse faults with dips less than 45 degrees |
| Strike slip faults or lateral slip faults | dominant slip is to the right or left along the fault |
| right lateral slip fault | the other side moves to the right |
| left lateral slip fault | the other side moves to the left |
| tensional forces pull apart forces | normal faults prevail found at the divergent plate boundaries |
| horst and graben structures | normal faults prevail |
| horst | uplifted block |
| Grabben | down dropped block normal faults |
| Compressional forces | found at the convergent plate margins |
| Joints | fractures with no appreciable displacement |
| shrinkage cracks | from igneous rocks cooling |
| Sheeting | unloading cracks |
| Fault block mountains | bounded on at least one side by high to moderate angle normal faults |
| Basin and ranges province | upwelling of hot mantle stretches crust 200 to 300 kilometers |
| Example of fault block mountains | Sierra Nevada Teton Range |
| Folded mountains | most major mountain belts |
| Example of folded mountains | Appalachian mountains alps Himalaya mountains |
| Up-warped mountains | Caused by broad arching of crust |
| Examples of Up-warped mountains | Black Hills Andirondack mountains |
| Mountain building | at convergent boundaries |
| Oceanic-continental convergent boundaries | Where oceanic crust is being subducted below continental crust |
| Passive continental margins | Continent is depositing sediment onto oceanic crust |
| Subduction zone forms | Between oceanic plate and continental plate |
| Parallel mountain belts form | accretionary wedge oceanic sediments are scraped form sub-ducting oceanic plate |
| Example of parallel mountain belts | California coast ranges |
| Volcanic arc | melted oceanic crust rises thorugh continental crust to form volcanic and plutonic mountain ranges |
| Example of Volcanic arc | Sierra Nevada Andes Mountains |
| Example Ocean-Ocean convergent boundaries | Aleatian Islands Alaska |
| Example Continental-Continental boundaries | Himalaya mountains |
| Collision result in | folding continents buoyant to subduct |
| Mountain building and continental accretion | smaller crust fragments pealed off sub-ducting plate pushed onto edge of continent distinct individual blocks are called terraces |
| Terrances | do not belong where they are |
| ridges plates move | on the soft asthenosphere |
| at which plate boundary is oceanic plates destroy | convergent |
| what structure is found between spreading ridges | transform faults |
| the Himalaya mountain are an example of | continental continental convergence |
| Hawaiian island are an example of | shield volcanoes |
| Southern California example of a left lateral slip fault is | Garlock |
| Which seismic wave travel fastest | P Waves |
| Tectronic plate boundaries where new seafloor is created are called | divergent boundaries |
| 79% Nitrogen 20% Oxygen 1% Argon Trace Gases | Ari is compose of |
| The crust process of finding a new level of equilibrim | Isostatic Adjustment |
| Which fault prevail when rocks are under tension forces | Normal Fault |
| Which faults prevail when rocks are under compression | Reverse Fault |
| A circular fold which have older rocks in the core is a | Dome |
| The compass direction of the intersection of a horizontal plane and a dipping plane is called the | Strike |
| Which has viscous thick lava | Rhyolite |
| Mount Lassen and Mt Shasta are which types of volcano | Composite |
| What is a volcanic crater greater than 1 Kilometer wide called | Caldera |
| An intrusive igneous rock body greater than 64 kilometer is a | Batholith |
| A circular fold produced by up warping so that the older rocks are in the center is called a | Dome |
| The present is the key to the past describes which theory | Uniformitarianism |
| An erosional surface with parallel strata on either side is called | Nonconformity |
| Fossil preservation where pores and cavities of plants or animals are filled with minerals is called | Petrification |
| The first step in the carbon 14 cycle is | Nitrogen 14 absorbs a neutron |
| Interbeded algal mats and silt are preserved as fossil | stromatolites |
| Half-life | 5730 years |
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