Objectives  I will know what earthquakes are and how they are monitored on earth  I will be able to analyze graphs and data to draw conclusion about earthquakes.

Defining Earthquakes  Shaking and trembling of the earth’s crust.  More than 1,000,000 occur a year or one every 30 seconds  Faulting is the most common cause  Earthquakes continue until all the energy is absorbed into the surrounding Earth’s material (dirt, rocks, buildings, etc.)  TSUNAMIS- an earthquake occurs on the ocean floor causing waves to become greater than 20 meters.

Seismic Waves  FOCUS- underground point of origin  EPICENTER- aboveground point of origin; most violent shaking occurs at the epicenter  The three main types of seismic waves are: P waves, S waves, and L waves

Shadow Zone  Shadow Zone- is the area where no s-waves travel because they can not travel through the liquid outer core  Opposite side of the Earth from then the Focus

P Waves  Primary waves  Arrive first at the epicenter  Can travel through solids, liquids, and gases  They are push-pull waves

S Waves  Secondary waves  Can travel through solids, but NOT through liquids and gases  Move in up-down motion

L Waves (Love Waves)  Surface waves  Slowest moving seismic waves  Travel on top of Earth’s surface  Cause most of damage to Earth, because they bend and twist the surface

How Earthquakes are Measured  Seismograph-measures and detects seismic waves  Seismogram- Paper record of waves  Seismologist- scientist who study earthquakes  Richter Scale- a scale that allows scientists to determine earthquake strength based on many readings  1-10 levels at which an earthquake is measured on amount of damage caused; Above a 6 is very destructive

Reading a Seismograph  Find the P-Wave arrival time  0 sec  Find the S-wave arrival time  38 sec  Find the S-P Interval  38 sec  Find the Amplitude  180mm

NEXT YOU WILL BE COMPLETING: the virtual earthquake activity