Earthquakes and Volcanoes Flash Cards
What is the Mercalli Scale?
1-12 rating using Roman numerals. It is subjective (based on opinion) and it rates the damage from an earthquake.
What is the Moment Magnitude Scale?
It is the most reliable scale and preferred by scientists because it is a calculation. It calculates the area ruptured by the fault and the distance the Earth moved.
What is a P wave?
P waves are PRIMARY WAVES. They move in a spring-like motion; they compress and expand. It is the fastest wave and it reaches the seismic stations first.
What is an S wave?
S waves are SECONDARY WAVES. They move ⬆️⬇️⬅️➡️. They are also half the speed of P waves.
What are surface waves?
Surface waves are the slowest energy of wave. It is also the most destructive.
What is a seismograph? How does it work?
The machine that measures the strength of an earthquake. HOW IT WORKS: 1) Incoming seismic waves. 2) Drum vibrates and rotates. 3) Pen documents on paper.
What is the Richter Scale?
The scale that rates the strength of an earthquake from 1-10. Each step is a tenfold increase.
What is a seismogram?
The reading of an earthquake’s strength that comes from a seismograph. It is a paper print-out.
What are seismic waves?
The waves that are given off by an earthquake. It is energy that moves the ground.
What is the Triangle of Uncertainty?
The area where circular signals from three earthquake detecting stations in three cities intersect, creating a triangle which shows the epicenter.
What is the epicenter?
The area directly above the focus on land.
What is the focus? What is a focus also called?
The focus is the starting point of an earthquake below ground. A focus is also called a hypocenter.
What is the plate boundary that earthquakes occur at?
Transform boundary.
What is the fault that earthquakes occur at?
Strike-Slip fault.
What is the type of volcano with the highest lava viscosity? What is the type with the lowest?
Highest: Composite
Lowest: Shield
What are the three types of volcanoes?
Composite, shield, and cinder cone.
How does a composite volcano form?
Subduction occurs (a oceanic plate sinks under a continental plate).
What makes a composite volcano unique?
Inside, layers of lava alternate with layers of ash. Also, the eruptions alternate with quiet ones and explosive ones.
How does a shield volcano form?
Lava from vents gradually build a wide, gently sloping mountain.
What makes a shield volcano unique?
It has a quiet eruption which gives off fluid lava. The volcano also forms on hot spots.
How does a cinder cone volcano form?
Ash, cinder, and bombs from other high viscosity volcanic eruptions build around a vent in a steep, cone shaped hill or small mountain.
What makes a cinder cone volcano unique?
It is made by other volcanoes, but still has an explosive eruption.
Give real world examples of all three types of volcanoes.
Composite: Mt. St. Helens
Shield: Mauna Loa Volcano
Cinder Cone: Sunset Crater
What is the difference between magma and lava?
Magma is molten rock underneath Earth’s surface in magma chambers and volcanoes (higher temp.). Lava is magma on Earth’s surface (lower temp.).
