Earthquakes Flashcards
How do earthquakes occur?
They occur when two tectonic plates slip past one another.
What is the surface where two tectonic plates slip past each other?
It is called the fault or fault plane.
What is the focus?
The location below the earth’s surface where the earthquake starts.
What is the epicenter?
The location directly above the focus on the surface of the earth
What are foreshocks?
These are smaller place earthquakes that happen in the same as the larger earthquake that follows.
Scientists can’t tell that an earthquake is a foreshock until the ______ earthquake happens.
Larger
What is the largest main earthquake called?
The main shock
What are aftershocks?
These are smaller earthquakes that occur afterwards in the same place as the main shock.
How long can aftershocks last?
Weeks, Months and even years.
What are the two ways scientists quantify the size of earthquakes?
Magnitude and intensity
What is magnitude?
Magnitude is a measure of the amount of energy released during an earthquake.
What is intensity?
It refers to the effect of the earthquake
What are earthquakes recorded by?
Instruments called seismographs
What recordings do seismographs make?
Seismogram
When was the Richter scale invented?
1930
What is the Richter Scale?
It is used to measure the largest seismic wave on the seismogram.
The Richter scale uses a _______ scale.
Logarithmic
Explain how the Richter scale works:
It uses a logarithmic scale. A specific seismogram located 100km away from the epicenter of an earthquake. A wave one millimeter high on a seismogram would have a magnitude of 3 because 1000 is ten raised to the third power. In contrast, a wave ten millimeters high would have a magnitude of 4.
What do we mean if we say the Richter scale is open-ended?
There is no limit to how small or large an earthquake might be.
Before the Richter scale was invented the effects of earthquakes at different locations was _______ and ________. Intensity is measured using the modified ___________. This scale uses Roman Numerals to describe earthquake intensity. An earthquake intensity of I is generally not felt, and an intensity of XII represents total destruction of buildings.
Observed
Recorded
Mercalli Scale
