lab exam 2 notes
How'd you figure out question 11 on the earthquake sheet? "If the first p-waves were recorded on the seismogram in Tokyo at 5:46:56 AM what time did the earthquake actually occur? Show your work."
Distance divided by speed. Then subtract that number from the time it was recorded. Remember you're subtracting time.
matter that L waves can travel through?
Earth's surface
Which seismic waves cause damages?
Surface (L) waves
focus vs. epicenter?
The location where the rocks move along the opposing sides of a fault to produce an earthquake is often deep within the Earth's crust known as the earthquake's focus. The depth may vary depending on the location or nearby plate boundary. The geographic location on the Earth's surface directly above the focus is termed the epicenter, and is often used in the press.
Explain the doctrine of uniformitarianism in further detail.
The physical, chemical, and biological laws that operate today have also operated in the geologic past: "The present is the key to the past." We use evidence from what we see happening on Earth today to determine what happened in the past by looking at the evidence left behind. For example, fish live in water; if we find a fish fossil there must have been water there in the past.
Provide two ways to determine the flow of a stream using contour lines
The point of a V in contour lines points in the opposite direction that the stream is flowing, you can also determine the elevation lines, and considering water flows downhill, the lower elevations are the direction it flows
properties of surface waves?
Unlike body waves, surface waves can only travel along the surface of the Earth similar to waves in the ocean. They are the slowest of all the waves (~2.5 km/sec.) and therefore are the last to arrive and the last to be recorded on a seismograph. Surface waves are much larger in amplitude and therefore are responsible for most of the damage. These waves can affect the crust in two ways; an undulatory, wavelike motion, and a side-to-side shaking. These potentially destructive waves can fracture the crust, break foundations, and knock over homes.
properties of secondary waves?
a little slower than p-waves, ~3.5 km/sec, and therefore are the second to reach a location and second to be recorded on a seismograph. S-waves are shear waves meaning they shift the crust up and down as they travel through like whipping a rope. S-waves can only travel through solids.
Why did you need three seismic stations to determine the epicenter of the earthquake?
because each seismic station creates a circle around it, and when all 3 are drawn they all intersect at one point, this point is the epicenter
slope formula?
change in elevation (tall-short) over distance = ft/mi
nature of p waves?
compress and extend the crust
properties of primary waves?
fastest, ~6 km/sec, first to reach location, first to be recorded, compressional waves meaning they compress and extend the crust as they travel through like a spring or slinky. These waves can travel through solids, liquids, and gases.
What is younger? Faults or rock?
faults
What is younger? rock or inclusions?
inclusions
Explain half life in further detail
it is the time it takes half of the parent to decay to the daughter. After one half-life 50% of the parent remains and 50% of the daughter is created. Then, that 50% parent continues to decay to 25% by 2 half-lives creating 75% daughter. Refer to the graph for help on how percentages and half-lives coincide.
How was the geologic timescale determined?
it was developed to separate events in Earth's history into specific ranges of time before the present.. It was based on Fossil Succession or the evolutionary change of life forms over Earth's history. The dates were added later, after the birth of radioactive dating techniques. Periods are not based on time, but instead the life forms present during that time range. Some separations are much longer than others. The older time periods are subdivided much less due to less preserved fossil evidence to differentiate changes in life forms.
formula for calculating map series?
latitude at the top - latitude at the bottom longitude on left - longitude on right should be the same answer, answer is map series
If you had a 15 minute quadrangle map you would be able to see (more/less) detail and (more/less) area.
less; more
What is the proper order of PLS?
quarters smallest to largest, section, township, range
What runs east to west? township or range?
range
Difference between absolute and relative dating?
relative is the sequence while absolute is numeric.
What does relative dating relate to? teachers question.
sequence - in order
nature of s waves?
shift the crust up and clown
matter that s waves can travel through?
solids
matter that p waves can travel through?
solids, liquids, and gases
Give details about the geologic timescale
the geologic timescale was developed to separate events in Earth's history into specific ranges of time before the present. It was based on Fossil Succession or the evolutionary change of life forms over Earth's history. The dates were added later, after the birth of radioactive dating techniques. Periods are not based on time, but instead the life forms present during that time range. Some separations are much longer than others. The older time periods are subdivided much less due to less preserved fossil evidence to differentiate changes in life forms.
What additional information would you need to determine the depth of the focus of the earthquake?
the s-p interval at the epicenter
What are the basic rules of contour lines?
they will never split, end, or cross one another
What runs north to south? township or range?
township
What is the name of the method you used to determine the epicenter?
triangulation of the epicenter
nature of L waves?
undulatory wavelike motion and side-to-side shaking
speed of surface (L) waves?
~2.5 km/sec
speed of secondary (S) waves?
~3.5 km/sec
speed of primary (P) waves?
~6 km/sec
