Plate tectonics, earthquakesand tsunamis

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

GATE GeologyParadise Canyon Elementary SchoolLa Canada, California 9 February 2005

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Plate tectonics, earthquakesPlate tectonics, earthquakesand tsunamisand tsunamis

• Part 1Part 1 - plate tectonics - plate tectonics

• Part 2Part 2 - earthquakes - earthquakes

• Part 3Part 3 - tsunamis - tsunamis

• Part 4Part 4 - California hazards - California hazards QuickTime™ and aTIFF (Uncompressed) decompressor

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Motion betweenthe plates causesearthquakes andvolcanoes

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Tilly Smith, 10 years old, saved Tilly Smith, 10 years old, saved people from the tsunami !people from the tsunami !

LONDON — A British schoolgirl who recognized the signs of a LONDON — A British schoolgirl who recognized the signs of a coming tsunami thanks to a recent geography lesson saved coming tsunami thanks to a recent geography lesson saved her family and some 100 other tourists at a Thai beach, a her family and some 100 other tourists at a Thai beach, a British newspaper reported.British newspaper reported. Tilly SmithTilly Smith, 10, realized they were in , 10, realized they were in danger when she saw the tide suddenly rush out — an indication danger when she saw the tide suddenly rush out — an indication earthquake-driven tidal waves are only minutes away — and told her earthquake-driven tidal waves are only minutes away — and told her mother. She explained that she had studied tsunamis only two weeks mother. She explained that she had studied tsunamis only two weeks before at her school in Oxshott, just south of London. Her parents, before at her school in Oxshott, just south of London. Her parents, Penny and Colin Smith, warned nearby vacationers and staff at their Penny and Colin Smith, warned nearby vacationers and staff at their hotel in Phuket, and the hotel swiftly evacuated Maikhao beach, hotel in Phuket, and the hotel swiftly evacuated Maikhao beach, minutes before the devastating waves struck.The beach was one of minutes before the devastating waves struck.The beach was one of only a few in Phuket where no one was killed or seriously hurt. "I was only a few in Phuket where no one was killed or seriously hurt. "I was on the beach and the water started to go funny," Tilly said. "There on the beach and the water started to go funny," Tilly said. "There were bubbles and the tide went out all of a sudden. I recognized what were bubbles and the tide went out all of a sudden. I recognized what was happening and had a feeling there was going to be a tsunami. I was happening and had a feeling there was going to be a tsunami. I told mummy."told mummy."

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Movie by T. Atwater, UCSB

Part 1. Plate TectonicsPart 1. Plate Tectonics

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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

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Earthquakes & PeopleEarthquakes & People

Earthquakessometimes hitbig cities

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Where the India plate is pusheddown beneath the Banda micro-plate, it is being SUBDUCTED.

Where the two plates’ surfacesare sliding past each other, itgets caught for hundreds ofyears and then the stored stressis released in a big earthquake.

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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

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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

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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)

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MerapiMerapivolcano,volcano,JavaJava

Strato-volcanoeserupt igneous rocks!

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LocationLocation

• Epicenter nearEpicenter near

Simeulue IslandSimeulue Island

• AftershocksAftershocks

extend past theextend past the

Nicobar andNicobar and

Andaman Andaman IslandsIslands

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If you If you feel anfeel anearth-earth-quake,quake,get toget tohighhighground!ground!

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