EES 1030 Lecture 11 Outline of Last Lecture I. Structural GeologyII. Mapping Geological StructuresIII. Investigation of the shallow EarthIV. Style of Rock DeformationV. Brittle DeformationVI. FaultsVII. Dip-Slip FaultsVIII. Strike-Slip FaultsIX. Ductile Deformation: FoldsX. MonoclinesXI. Domes and BasinsOutline of Current Lecture XII. EarthquakesXIII. SeismologyXIV.Distribution of EarthquakesXV. Measuring the size of earthquakesXVI. Earthquake DamageXVII. TsunamisThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best Used as a supplement to your own notes, not as a substitute.XVIII. Can earthquakes be predicted?Current Lecture- Earthquakeso Sudden release of energy accumulated in deformed rocks: radiates as seismic waveso Focus = site of initial ruptureo Seismic: Gxreek for “shaking”o Fault is locus of earthquake movement Not all earthquakes cause surface rupture- Seismologyo The study of earthquake or seismic waveso Types of seismic waves Body waves: travel through Earth’s interior.- Two types: Primary and secondary waves- Primary (P waves): compressional or push-pull waves. Fastest seismic waves (6km/s)- Secondary (S waves): shear or shaking waves. Travel at half speed of P waves (3.5 km/s in crust) Surface waves: travel over Earth’s surface, responsible for most earthquake damageo Locating Earthquake Source Focus: place within Earth where earthquake waves originate Epicenter: location on surface directly above focus Epicenter is located by difference in arrival times of P & S waves- Distribution of Earthquakeso Not random but focused around plate margins (but also seen in plate interiors)o Most earthquakes are shallow (<50km). Heat weakens rocks – less able to store strain energy- Measuring size of earthquakeso Intensity: measure of degree of earthquake shaking at a given locale based on damageo Influenced by: local geology, building design & construction Magnitude: estimates the amount of energy released at the source of the earthquake Richter Scale: Charles Richter 1935 Based on amplitude of largest seismic wave recorded, adjusted for distance to epicenter Moment magnitude: related to the physical properties of fault that caused the earthquake  better estimate of total energy released- Earthquake Damageo Extent of structural damage attributable to earthquake vibrations depend on: Depth of earthquake Intensity and duration of the vibrations Nature of the material the structure rests on Design of the structure Quality of construction Liquefaction: unconsolidated materials saturated with water turn into a mobile fluid. No strength to support buildings- Tsunamiso Destructive ocean waves triggered by movement of surface fault or landslideo Appear like a rapidly-rising tide- Can earthquakes be predicted?o Short-range predictions (days to weeks): Monitoring precursors that might precede an earthquake: uplift, subsidence, strain, weird animal behavior… no reliable method exists for making short-range earthquake predictionso Long-range forecast (decades to centuries): based on premise that earthquakes are repetitive or cyclical. Continued motion of Earth’s plate causes strain to build up again.  Historical records or