Plate tectonics, volcanoes, and earthquakes

Plate tectonics, volcanoes,and earthquakes

Ken HudnutKen HudnutU. S. Geological SurveyU. S. Geological Survey

Mr. Hajek’s 4th-grade classroomParadise Canyon Elementary SchoolLa Canada, California 3 October 2003

2 PCY

Plate tectonics, volcanoesPlate tectonics, volcanoesand earthquakesand earthquakes

• Part 1Part 1 - plate tectonics - plate tectonics

• Part 2Part 2 - volcanoes - volcanoes

• Part 3Part 3 - earthquakes - earthquakes

3 PCY

QuickTime™ and aAnimation decompressorare needed to see this picture.

Movie by T. Atwater, UCSB

Part 1. Plate TectonicsPart 1. Plate Tectonics

4 PCY

Motion betweenthe plates causesearthquakes andvolcanoes

5 PCY

Earthquakes and volcanoes are Earthquakes and volcanoes are driven by plate tectonic motiondriven by plate tectonic motion

• As a plate subducted, As a plate subducted, the Cascades the Cascades volcanoes and San volcanoes and San Andreas fault were bornAndreas fault were born

• The subducting plate The subducting plate melts and the magma melts and the magma rises up to form rises up to form volcanoesvolcanoes

• The plates sliding past The plates sliding past each other make the each other make the active transform faultsactive transform faults

Movie by T. Atwater, UCSB

QuickTime™ and aAnimation decompressorare needed to see this picture.

6 PCY

7 PCY

Worksheet on Worksheet on Plate EdgesPlate Edges

• Plate edges are of three typesPlate edges are of three types

• Plates pull away from each otherPlates pull away from each other

• Plates push towards each otherPlates push towards each other

• Plates slide past each otherPlates slide past each other

8 PCY

Part 2. VolcanoesPart 2. Volcanoes

QuickTime™ and aMotion JPEG A decompressorare needed to see this picture.

Eruption of Stromboli, Italy

9 PCY

Motion betweenthe plates causesearthquakes andvolcanoes

This is really bad news for people (like us!) living around the Pacific Rim, also known as the Ring of Fire

10 PCY

Why do volcanoes erupt?Why do volcanoes erupt?

• Pressure builds up Pressure builds up because of heat and because of heat and trapped gas bubblestrapped gas bubbles

• Cracks open and lava, Cracks open and lava, steam and ash blast outsteam and ash blast out

• Sticky magma makes Sticky magma makes tall cone-shaped tall cone-shaped volcanoes (like Merapi)volcanoes (like Merapi)

• Runny magma makes Runny magma makes low, broad volcanoes low, broad volcanoes (like Kilauea, Hawai’I)(like Kilauea, Hawai’I)

11 PCY

MerapiMerapivolcano,volcano,JavaJava

Strato-volcanoeserupt igneous rocks!

12 PCY

WestdahlWestdahlvolcano,volcano,AlaskaAlaska

QuickTime™ and aBMP decompressorare needed to see this picture.Volcanoes inflatewith magma, anddeflate with lava

13 PCY

Worksheet on Worksheet on Ring of FireRing of Fire

• Plates crash into each other, causing Plates crash into each other, causing high mountains and low ocean floor high mountains and low ocean floor called trenchescalled trenches

• Deepest trench is the Marianas (esp. at the Deepest trench is the Marianas (esp. at the ‘Challenger Deep’ location shown on map)‘Challenger Deep’ location shown on map)

• Highest mountain is Mt. EverestHighest mountain is Mt. Everest

14 PCY

Worksheet: hot spot track - islands cool, erode, & sink

15 PCY

Part 3. EarthquakesPart 3. Earthquakes

Earthquakesare a globalproblem

16 PCY

Earthquakes are driven by plate Earthquakes are driven by plate tectonic motiontectonic motion

• In the past 5 million In the past 5 million years, this motion years, this motion has been steady at has been steady at about 2 inches per about 2 inches per year year (that’s 15 feet (that’s 15 feet per century or 30 per century or 30 miles per million miles per million years!)years!)

• Yes, LA will be in Yes, LA will be in San FranciscoSan Francisco

• No, LA will not fall No, LA will not fall into the seainto the sea

Movie by T. Atwater, UCSB

QuickTime™ and aAnimation decompressorare needed to see this picture.

17 PCY

Earthquakes are Earthquakes are not onlynot only California’s problem California’s problem$30M of oil each day!

18 PCY

Houston, we have a problem…Houston, we have a problem…

19 PCY

Southern California is the nation’s most Southern California is the nation’s most dangerous place for earthquakes - why?dangerous place for earthquakes - why?

Silver linings:State-of-the-art earthquake monitoring arraysMany of the world’s best researchers work within this natural laboratory

20 PCY

The San Andreas faultThe San Andreas fault

21 PCY

San Andreas faultSan Andreas fault• Most of the plate Most of the plate

boundary motionboundary motion• 1685, 1812, 1857 eq’s1685, 1812, 1857 eq’s

• Big Bend compressionBig Bend compression• 1971 Sylmar (M 6.7)1971 Sylmar (M 6.7)• 1994 Northridge (M 6.7)1994 Northridge (M 6.7)

• SoCal is now heavily SoCal is now heavily ‘wired’ (much like ‘wired’ (much like Japan & Taiwan)Japan & Taiwan)• SeismicSeismic• GPSGPS

22 PCY

GPS

23 PCY

‘A rip in the desert canvas’- Los Angeles Times

Katherine Kendrick, USGS

Chris Walls, Earth Consultants International

24 PCY

Flying the fault line…Flying the fault line…

QuickTime™ and aDV/DVCPRO - NTSC decompressorare needed to see this picture.

25 PCY

Conclusions:Conclusions: • Earth is a very active Earth is a very active planet - that’s both a planet - that’s both a good and bad thinggood and bad thing

• Humans can survive Humans can survive despite natural hazards - despite natural hazards - tragic losses from tragic losses from volcanoes & earthquake volcanoes & earthquake are not inevitableare not inevitable

• Natural beauty results Natural beauty results from plate tectonics - we from plate tectonics - we can study & understand can study & understand the world around usthe world around us