EARTHQUAKES, SEISMIC WAVES, & MONITORING SYSTEMS

Earthquake Shaking and trembling from movement of the Earth’s plates Shaking and trembling from movement of the Earth’s plates More than 8,000 quakes everyday More than 8,000 quakes everyday Focus-point where earthquake begins Focus-point where earthquake begins Epicenter- point on Earth’s surface above the focus Epicenter- point on Earth’s surface above the focus

Seismic Waves Carry energy away from the earthquake Carry energy away from the earthquake P wave: 1 st waves and they compress and expand P wave: 1 st waves and they compress and expand S wave: secondary waves and they vibrate side to side S wave: secondary waves and they vibrate side to side Surface wave: travel on the surface and produce ground movement Surface wave: travel on the surface and produce ground movement

P-wave P-wave S-wave S-wave

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

Measuring Earthquakes (2) Richter scale- measures an earthquake’s magnitude (strength) Richter scale- measures an earthquake’s magnitude (strength) Seismograph- measures wave strength Seismograph- measures wave strength

Measuring Earthquakes (3) Movement Magnitude Scale: estimates the total energy released by the earthquake Movement Magnitude Scale: estimates the total energy released by the earthquake

Comparing Magnitudes One-point increase in magnitude represents 32 times as much energy as the one before One-point increase in magnitude represents 32 times as much energy as the one before

Locating the Epicenter Seismic waves are used. P waves travel faster than S waves Seismic waves are used. P waves travel faster than S waves

Locating the Epicenter

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

Mapping Faults Scientists study faults and the movement along them Scientists study faults and the movement along them Friction- force that opposes motion of one object sliding over another object Friction- force that opposes motion of one object sliding over another object

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