The Richborough hoard of 'radiates', 1931 / by Harold Mattingly and W.P.D. Stebbing
Warm Up 10/21(22) 1. When an earthquake occurs, energy radiates in all directions from its source,...
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Transcript of Warm Up 10/21(22) 1. When an earthquake occurs, energy radiates in all directions from its source,...
Warm Up 10/21(22)Warm Up 10/21(22)1.1. When an earthquake occurs, energy radiates in all When an earthquake occurs, energy radiates in all
directions from its source, which is called the ____.directions from its source, which is called the ____.a. faulta. fault c. seismic centerc. seismic centerb. epicenterb. epicenter d. focusd. focus
2.2. The hypothesis that explains the release of energy during The hypothesis that explains the release of energy during an earthquake is called the ____.an earthquake is called the ____.a. moment magnitude hypothesisa. moment magnitude hypothesis c. Richter c. Richter hypothesishypothesisb. elastic rebound hypothesisb. elastic rebound hypothesis d. vibration d. vibration hypothesishypothesis
3.3. Most earthquakes are produced by the rapid release of Most earthquakes are produced by the rapid release of which kind of energy stored in rock subjected to great which kind of energy stored in rock subjected to great forces?forces?a. thermala. thermal c. chemicalc. chemicalb. elasticb. elastic d. Mechanicald. Mechanical
1. d, 2. b, 3. b
Earth’s Layered Earth’s Layered StructureStructure
Chapter 8, Section 4Chapter 8, Section 4
Layers Defined by CompositionLayers Defined by Composition If Earth were made up of the same If Earth were made up of the same
materials throughout its interior, seismic materials throughout its interior, seismic waves would travel in straight lines at waves would travel in straight lines at constant speedsconstant speeds
Seismic waves reaching seismographs Seismic waves reaching seismographs located farther from an earthquake travel located farther from an earthquake travel at faster average speeds, due to increased at faster average speeds, due to increased pressure at depthpressure at depth
Earth’s interior consists of three major Earth’s interior consists of three major zones defined by its chemical composition zones defined by its chemical composition – the crust, mantle, and core– the crust, mantle, and core
Paths of Seismic RaysPaths of Seismic Rays
The CrustThe Crust Crust –Crust – thin, rocky, outer layer of Earth; thin, rocky, outer layer of Earth;
divided into oceanic and continental crustdivided into oceanic and continental crust The oceanic crust is roughly 7 kilometers The oceanic crust is roughly 7 kilometers
thick and composed of the igneous rocks thick and composed of the igneous rocks basalt and gabbrobasalt and gabbro
The continental crust is 8-75 kilometers The continental crust is 8-75 kilometers thick (avg. 40 km) and consists mostly of thick (avg. 40 km) and consists mostly of the granitic rock granodioritethe granitic rock granodiorite
The rocks of the oceanic crust are younger The rocks of the oceanic crust are younger then the rocks of the continental crustthen the rocks of the continental crust
Mantle and CoreMantle and Core
Mantle – Mantle – a solid, rocky shell that a solid, rocky shell that extends to a depth of 2890 kmextends to a depth of 2890 km
Over 82% of Earth’s mass is Over 82% of Earth’s mass is contained in the mantlecontained in the mantle
The boundary between the crust and The boundary between the crust and mantle represents a chemical mantle represents a chemical composition changecomposition change
Core – Core – a sphere composed of an a sphere composed of an iron-nickel alloyiron-nickel alloy
Concept CheckConcept Check
What is the composition of the core?What is the composition of the core? An iron-nickel alloyAn iron-nickel alloy
Layers Defined by Physical Layers Defined by Physical PropertiesProperties
Earth’s interior has a gradual increase in Earth’s interior has a gradual increase in temperature, pressure, and density with temperature, pressure, and density with depthdepth
Depending on the physical environment Depending on the physical environment (temperature and pressure), a material (temperature and pressure), a material may behave like a brittle solid, a putty, or may behave like a brittle solid, a putty, or a liquida liquid
Earth can be divided into layers based on Earth can be divided into layers based on physical properties – the lithosphere, physical properties – the lithosphere, asthenosphere, outer core, and inner core.asthenosphere, outer core, and inner core.
Lithosphere and AsthenosphereLithosphere and Asthenosphere
Lithosphere – Lithosphere – relatively cool, rigid relatively cool, rigid shell consisting of the crust and shell consisting of the crust and upper most mantleupper most mantle
Averages about 100 kilometers in Averages about 100 kilometers in thicknessthickness
Asthenosphere – Asthenosphere – soft, soft, comparatively weak layer beneath comparatively weak layer beneath the lithospherethe lithosphere
The rocks within the asthenosphere The rocks within the asthenosphere are close enough to their melting are close enough to their melting points that they are easily deformedpoints that they are easily deformed
Lower MantleLower Mantle
From a depth of 660 km down to From a depth of 660 km down to near the base of the mantlenear the base of the mantle
More rigid layer that is still prone to More rigid layer that is still prone to gradual flowgradual flow
At the bottom of the mantle, rocks At the bottom of the mantle, rocks behave more like those in the behave more like those in the asthenosphereasthenosphere
Inner and Outer CoreInner and Outer Core
The core, which is composed of an The core, which is composed of an iron-nickel alloy, is divided into two iron-nickel alloy, is divided into two regions with different physical regions with different physical propertiesproperties
Outer Core –Outer Core – liquid layer 2260 km liquid layer 2260 km thick, flow produces Earth’s magnetic thick, flow produces Earth’s magnetic fieldfield
Inner Core –Inner Core – sphere with a radius of sphere with a radius of 1220 km, compressed into a solid 1220 km, compressed into a solid state by immense pressurestate by immense pressure
Earth’s Layered StructureEarth’s Layered Structure
Concept CheckConcept Check
Why is the inner core solid?Why is the inner core solid? It is under extreme pressure and is It is under extreme pressure and is
compressed into a solid as a resultcompressed into a solid as a result
Discovering Earth’s LayersDiscovering Earth’s Layers Moho –Moho – boundary separating the crust from the boundary separating the crust from the
mantle where the velocity of seismic waves mantle where the velocity of seismic waves abruptly increasesabruptly increases
Seismic waves from even small earthquakes Seismic waves from even small earthquakes can travel around the worldcan travel around the world
The outer core causes P waves that travel The outer core causes P waves that travel through it to arrive several minutes after through it to arrive several minutes after expected and are bent by 100expected and are bent by 100oo away from the away from the earthquake (shadow zone)earthquake (shadow zone)
It was further shown that S waves do not travel It was further shown that S waves do not travel through the outer core, making geologists through the outer core, making geologists conclude that the outer core is composed of a conclude that the outer core is composed of a liquidliquid
Concept CheckConcept Check
What is the Moho?What is the Moho? The boundary between the crust and The boundary between the crust and
the mantlethe mantle
Discovering Earth’s CompositionDiscovering Earth’s Composition Early seismic data and drilling technology Early seismic data and drilling technology
indicate that the continental crust is indicate that the continental crust is mostly made of lighter, granitic rocksmostly made of lighter, granitic rocks
The crust of the ocean floor has a baslatic The crust of the ocean floor has a baslatic compositioncomposition
The composition of the mantle and core is The composition of the mantle and core is known from more indirect dataknown from more indirect data
Scientists use lava and meteorites to infer Scientists use lava and meteorites to infer the composition of the mantle and corethe composition of the mantle and core
Earth’s core is thought to be mainly dense Earth’s core is thought to be mainly dense iron and nickel, similar to metallic iron and nickel, similar to metallic meteorites. The surrounding mantle is meteorites. The surrounding mantle is believed to be composed of rocks similar believed to be composed of rocks similar to stony meteoritesto stony meteorites
Earth’s Interior Showing P and S Earth’s Interior Showing P and S Wave PathsWave Paths
AssignmentAssignment
Read Chapter 8, Section 4 (pg. 233-237)Read Chapter 8, Section 4 (pg. 233-237) Do 8.4 Assessment #1-6 (pg. 237)Do 8.4 Assessment #1-6 (pg. 237)