Volcanoes and Earthquakes

DAY 1 Objective: I can explain how a volcano is structured

What is a Volcano? A mountain formed of lava and/or pyroclastic material

Anatomy of a Volcano Vent Crater Magma Chamber Magma Tube Opening in the crust Crater Steep-walled depression at the top Magma Chamber Where the molten rock waits Magma Tube Links the vent to the magma chamber

Day 2 Objective: I can explain what happens when a volcano erupts

Magma verse Lava Magma Lava Molten rock under the surface of Earth Molten rock on the surface of Earth

Factors Affecting Eruption Magma Composition Magma Temperature Amount of Dissolved Gases

Viscosity of Magma Substance’s resistance to flow Hotter the magma, more fluid and less viscous Directly related to its silica content More silica, greater its viscosity (slower movement)

Dissolved Gases Consist of water vapor and carbon dioxide More gases, the more violent the eruption

Gases 70% water vapor 15% carbon dioxide 5% nitrogen 5% sulfur

Pyroclastic Material Fragments ejected during eruptions From very fine to several tons Ex: Volcanic Ash Cinders (lapilli) Volcanic Bombs

Other Eruption Results Pyroclastic Flow Consist of hot gases, glowing ash, and large rock fragments Races down the steep slope Lahar Mudflow that occurs when volcanic debris becomes saturated with water and rapidly moves down steep volcanic slopes

DAY 3 Objective I can describe the locations of volcanoes and the relationship between volcanoes and plate tectonics

Plate Tectonics & Volcanoes Relationship Plate movement provided the mechanism by which mantle rock melts to generate magma

Ring of Fire Area around the pacific ocean with extreme volcanic activity This shows the Pacific Plate Boarder

Intraplate Activity Occurs with a plate, not a plate boundary Hot Spots Small volcanic region a few hundred kilometers across within a plate Ex: Hawaiian Islands

DAY 4 Objective: I can explain what an earthquake is I can explain why earthquakes happen

What is an Earthquake? Vibration of Earth Produced by a sudden release of energy Movement along a fault line

Parts of an Earthquake Focus Epicenter Fault Point within Earth where the earthquake starts Epicenter Location on the surface directly above the focus Fault Associated with earthquakes activity where movement has occurred

Causes of Earthquakes Elastic Rebound Hypothesis Release of built-up energy Most earthquakes are produced by the rapid release of elastic energy stored in rock that has been subjected to great forces When the strength of the rock exceeded, it suddenly breaks, causing the vibrations of an earthquake

Foreshock vs. Aftershock Small earthquakes before the big quake Aftershock Smaller earthquakes after the big quake

Seismic Science Seismology Seismograph Seismogram Study of earthquake waves Seismograph Instruments that record earthquakes Seismogram The record made by a seismograph

Day 5 Objective: I can explain how to locate origin of an earthquake I can explain how to measure the strength of an earthquake

Earthquake Waves Two Main Types Surface Waves Body Waves P-waves S-waves

Surface Waves Seismic waves that travel along Earth’s outer layer Moves up & down and side to side Most destructive Last to arrive at the seismograph

Body Waves P-Waves (primary waves) They push (compress) and pull (expand) rocks in the direction the wave travels Can travel through solids, liquids and gases Fastest waves First to the seismograph

S-Waves (secondary waves) Shakes particles at right angles to their travel Can only travel through solids 2nd to the seismograph

Locating Earthquakes The difference in velocity of a P-Wave & S-Wave provides a way to locate the epicenter Use a travel-time curve graph Needs at least three seismograph station data

Strength of an Earthquake Two different types of measurements to describe the strength of an earthquake Intensity Magnitude

Earthquake Intensity A measure of the amount of earthquake shaking at a given location based on the amount of damage

Earthquake Magnitude A measure of the size of seismic waves or the amount of energy released at the source of an earthquake

The Richter Scale Measures magnitude Based on the amplitude of the largest seismic wave A TEN-FOLD system Largest earthquake record= 9.6 (CHILE)

Moment Magnitude Scale More precise Amount of displacement that occurs along a fault zone Most widely used Estimates energy released by earthquakes

Mercalli Intensity Scale How much damage occurs Depends on: Strength Distance from the epicenter Nature of the surface material Building design

DAY 6 Objective: I can describe the dangers of an Earthquake I can explain how to make earthquake predictions

Earthquake Hazards Seismic Vibrations Damage to building depends on several factors Intensity of vibration Duration of vibration What type of material built on Design of the structure

Liquefaction Stable soil turns into a liquid that is not able to support building or other structures

Tsunami Large ocean wave created by an earthquake

Landslides Fires Caused by ruptured gas lines Greatest damage to structures Sinking of the ground triggered by the vibration Fires Caused by ruptured gas lines

Predicting Earthquakes Short Range Measure uplift, subsidence and strain in the rocks Short-range predictions have not been successful

Long Range Based on the idea that earthquakes are repetitive Seismic Gap An area along a fault where there has not been any earthquake activity for a long period of time