Tsunami Earthquake things Flashcards
Definition of Earthquake
the vibrations in the ground that result from the movement along breaks in Earth’s lithosphere
Definition of Fault
a fracture in the lithosphere where one block of rock moves toward, away from, or past another. Rocks bend as stress is put on them
Definition of Stress
the force exerted when an object presses on, against or pulls on another object (this occurs from the tectonic plates)
How is the intensity determined?
by the distance the rocks move along the fault and how much stress builds up before the rocks move
What are the three types of fault movements?
normal, reverse, strike-slip
What type of tectonic plate movement causes normal faults?
divergent
What type of tectonic plate movement causes reverse faults?
convergent
What type of tectonic plate movement causes strike-slip faults?
transform
Definition of Focus
the point underground where rocks first begin to move. Seismic waves travel outward from the earthquakes focus
Definition of Seismic Waves
the energy waves that travel as vibrations caused by earthquakes (these waves travel in all directions)
What are the three types of Seismic Waves?
Primary (fastest wave), Secondary (half as fast), Surface (slowest)
What are the three types of fault movements?
Normal, reverse, strike-slip
Definition of Epicenter
the point on earth’s surface directly above the focus
Definition of Seismograph
a device that constantly records movement of the ground. By studying seismographs once can find the location and strength of earthquake and focus
What is Aftershock?
a smaller earthquake that follows a more powerful earthquake
about __% of all earthquakes happen around the edges of the _______ _____
80%, pacific ocean
What is liquefaction?
Cause of a tsunami/dam breaking. Soil becomes soupy mud and cannot support structures anymore.
Name three methods to make buildings safer.
- Designed to reduce amount of ash
- Use base isolators, making the shaking slower and smoother
- Build an open space around buildings, causing a gentle shake
- Steel support walls
- Cross braces on walls
Why do scientists study seismic activity along faults
to predict earthquakes
Name two things scientists study to predict an earthquake.
- Changes or tilts in the ground
- Slow movement or stretching of rocks
- The development of cracks in the ground
How do you find the location of an earthquake
- find the difference between the arrival times of the primary and secondary waves
- the time difference is used to determine the distance of the epicenter from each station. The grater the difference in time, the greater the distance the epicenter is
- a circle is drawn around each station with a radius corresponding to the epicenter’s distance from that station. The point where the three circles meet is the epicenter
What do P and S waves do?
they change the speed and direction of seismic waves and they travel at different depths within Earth’s interior
Why can’t S-waves travel through the outer core
because its liquid
What are the inner core and other core mostly composed of
iron and nickel
TRUE OR FALSE
Seismic waves tend to slow down as they travel through hot material and are slower in areas in the mantle. They are faster in cool areas of the mantle near subduction zones.
true
Deep earthquakes occur along what tectonic plates
convergent tectonic plates
Shallow earthquakes occur along what tectonic plates
divergent tectonic plates
What kind of earthquakes are the most damaging
transform tectonic plates
Scientists discovered change in the earth interior from studying what?
seismic waves
A break in the earth’s lithosphere where rocks move towards and away from
earthquake
Which waves arrive first at the seismograph station
primary
What are the 3 stations that are used to measure the epicenter
triangulation
What waves happpen when there’s an earthquake and the land goes up and down
surface waves
TRUE OR FALSE
normal fault, rocks go down
true
TRUE OR FALSE
reversed fault, land goes up
true
What happens when a fault is on the surface and the land passes each other
strike-slip
Definition of magnitude
amount of energy released by an earthquake
Moment Magnitude Scale
determines the amount of energy release by earthquakes
Richter scale
determines how fast the ground moves
Modified Mercalli
determines earthquakes intensity based on descriptions of the effects
Definition of surface wave
move along the earth’s surface not the interior. Travel the slowest. Cause greatest ground movement and damage
Definition of primary waves
fastest wave, first to reach any location after earthquake. Particles of material are pushed together and pulled apart
Definition on secondary waves
travel half as fast, second wave to reach a location after an earthquake. Particles are shaken up, down,, side to side. Secondary waves can not travel through liquids
What fault line is it where rocks pull apart
normal
What measures the earth’s magnitude
richter scale
Earthquakes occur along plate boundaries along what ocean
pacific ocean
What direction do seismic waves travel
all directions
Definition of stress
force exerted on an object when presses or pulls against another
