EARTHQUAKES, SEISMIC EARTHQUAKES, SEISMIC WAVES, & MONITORING WAVES, & MONITORING

SYSTEMS SYSTEMS

EarthquakeEarthquake

Shaking and trembling Shaking and trembling from movement of the from movement of the Earth’s platesEarth’s plates

More than 8,000 More than 8,000 quakes everyday quakes everyday

Focus-point where Focus-point where earthquake beginsearthquake begins

Epicenter- point on Epicenter- point on Earth’s surface above Earth’s surface above the focus the focus

Seismic WavesSeismic Waves

Carry energy away Carry energy away from the earthquake from the earthquake

P wave: 1P wave: 1stst waves and waves and they compress and they compress and expandexpand

S wave: secondary S wave: secondary waves and they waves and they vibrate side to sidevibrate side to side

Surface wave: travel Surface wave: travel on the surface and on the surface and produce ground produce ground movement movement

P-waveP-wave

S-waveS-wave

Measuring EarthquakesMeasuring Earthquakes

Mercalli Scale- measures the amount of Mercalli Scale- measures the amount of damage on a scale of 1-12damage on a scale of 1-12

Measuring Earthquakes (2)Measuring Earthquakes (2)

Richter scale-Richter scale-measures an measures an earthquake’s earthquake’s magnitude magnitude (strength)(strength)

Seismograph- Seismograph- measures wave measures wave strength strength

Measuring Earthquakes (3)Measuring Earthquakes (3)

Movement Movement Magnitude Scale: Magnitude Scale: estimates the total estimates the total energy released by energy released by the earthquake the earthquake

Comparing MagnitudesComparing Magnitudes

One-point increase One-point increase in magnitude in magnitude represents 32 represents 32 times as much times as much energy as the one energy as the one beforebefore

Locating the EpicenterLocating the Epicenter

Seismic waves are used. P waves Seismic waves are used. P waves travel faster than S wavestravel faster than S waves

Locating Locating the the

EpicenteEpicenterr

The Modern SeismographThe Modern Seismograph

Seismic waves Seismic waves cause a drum to cause a drum to vibrate while an vibrate while an attached pen attached pen records the records the vibrations vibrations

Instruments to Monitor Faults Instruments to Monitor Faults (Predicting Earthquakes)(Predicting Earthquakes)

Tiltmeters- measures the raising of the Tiltmeters- measures the raising of the groundground

Creep Meters- a wire measures horizontal Creep Meters- a wire measures horizontal movement of the ground movement of the ground

More Instruments More Instruments

Laser-Ranging Devices: a Laser-Ranging Devices: a laser detects horizontal laser detects horizontal fault movements fault movements

GPS satellites: Monitor GPS satellites: Monitor changes in elevation and changes in elevation and hroizontal movements hroizontal movements with satelliteswith satellites

Mapping Faults Mapping Faults

Scientists study Scientists study faults and the faults and the movement along movement along them them

Friction- force that Friction- force that opposes motion of opposes motion of one object sliding one object sliding over another object over another object

Predicting EarthquakesPredicting Earthquakes

Scientists use their monitoring tools and Scientists use their monitoring tools and fault maps to make predictions but there fault maps to make predictions but there is no effective early warning system is no effective early warning system