Transcript earthquakes - District 128 Moodle

EARTHQUAKES
INTRODUCTION TO EARTHQUAKES
• Earthquake =
• a vibration of the
Earth produced by the
release of energy.
Seismology is the study of
earthquakes and seismic waves
that move through and around the
earth.
A seismologist is a scientist who
studies earthquakes and seismic
waves
What is the epicenter and focus of an earthquake?
• Energy that creates an earthquake moves out
from the focus.
• The focus is the place within the Earth where the
rocks breaks, producing an earthquake.
• The epicenter of an earthquake is the point on
the ground’s surface directly above the focus.
Waves associated with earthquakes
• Energy moving outward from the focus of an earthquake travels
in the form of seismic waves.
TYPES OF SEISMIC WAVES
• The two main types of seismic waves are body waves and
surface waves.
Body Waves
Surface Waves
HOW DO SCIENTISTS MEASURE
EARTHQUAKES
• There are two ways in which
scientists quantify the size of
earthquakes: magnitude and
intensity
• Earthquake magnitudes are
measured using the Richter
Scale.
WHERE ARE EARTHQUAKES MOST
COMMON?
• No part of the Earth’s surface is safe from earthquakes. But some
areas experience them more frequently than others.
• Earthquakes are most common at plate boundaries, where different
tectonic plates meet. The largest events usually happen where two
plates are colliding- this is where a large amounts of stress can build
up rapidly
About 80 percent of all
recorded earthquakes occur at
the circum-Pacific seismic belt,
commonly known as the Rim of
Fire due to the prevalence of
seismic and volcanic activity
Other facts about Earthquakes
put together…
• Tectonic earthquakes are most common
• Earthquake is in other words, a shaking or
trembling of the earth that accompanies rock
movements extending anywhere from the crust
to 680 km below the Earth's surface.
• The tsunami that hit Indonesia and killed more
than 150,000 people would be measured at 9.0
in Richter Scale.
• Earthquakes release stress which causes
permanent change in the Earth's crust.