Natural DisastersNatural Disasters

By: Patrick L. Abbott

Chapter 3Chapter 3

Basic Principles of Earthquake Geology and Seismology

OverviewOverview

The Lisbon Earthquake of 1755What is an Earthquake?Faults and Geological MappingTypes and FaultsDevelopment of SeismologySeismic Waves: Body Waves

Overview (cont.)Overview (cont.)

Seismic Waves and the Earth’s Interior

Seismic Waves: Surface WavesLove WavesRayleigh WavesTsunamiLessons from Tsunami

Overview (cont.)Overview (cont.)

Locating the Source of an Earthquake

Magnitude of EarthquakesGround Motion During EarthquakesEarthquake Intensity - What We Feel

During an Earthquake

The Lisbon Earthquake of The Lisbon Earthquake of 17551755

HistoryHistorical misconceptions

What is an Earthquake?What is an Earthquake?

FractureStress

Faults and Geologic MappingFaults and Geologic Mapping

Law of Original HorizontalityLaw of SuperpositionLaw of Original Continuity

Types of FaultsTypes of Faults

JointingDip and StrikeCross sectionMapPermeabilityFootwallHangingwall

Types of faults (cont.)Types of faults (cont.)

Dip-slip faults Normal faults Reverse fault

Strike-slip fault Right-lateral fault Left-lateral fault Hypocenter

Transform faults

Development of SeismologyDevelopment of Seismology

SeismologySeismometersSeismographsInertia

Seismic Waves: Body WavesSeismic Waves: Body Waves

Seismic WavesBody WavesSurface WavesPrimary Waves

GraniteSecondary Waves

Seismic Waves and the Seismic Waves and the Earth’s InteriorEarth’s Interior

PassageVarying velocities

Seismic Waves: Surface Seismic Waves: Surface WavesWaves

Love Rayleigh

Love WavesLove Waves

A. E. H. LoveCharacteristics

Rayleigh WavesRayleigh Waves

Lord RayleighCharacteristics

TsunamiTsunami

CharacteristicsSeicheTsunami versus Wind-Caused Waves

Periods Wavelengths

Lessons from TsunamiLessons from Tsunami

Alaska, 1 April 1946Chile, 22 May 1960Alaska, 27 March 1964Nicaragua, 1 September 1992Papua New Guinea, 17 July 1998

Locating the Source of an Locating the Source of an EarthquakeEarthquake

Arrival timesSeismogramRecording stations

Magnitude of EarthquakesMagnitude of Earthquakes

MagnitudePeriodFrequencyRichter ScaleOther Measures of Earthquake Size

Moment Magnitude Scale

Ground Motion During Ground Motion During EarthquakesEarthquakes

AccelerationPeriod and Resonance

Earthquake Intensity - What Earthquake Intensity - What We Feel During an We Feel During an EarthquakeEarthquake

Mercalli Scale Variables Earthquake magnitude Distance from hypocenter/epicenter Foundation materials Building style Duration of shaking