Plate Boundaries
What is the name for the boundary where two tectonic plates move away from each other and new crust is formed?
Divergent boundary (mid-ocean ridge)
Define a volcano in one sentence using information from the provided content.
An opening in the Earth’s crust where magma, gases, and ash escape; over time this can form a mountain.
Give a concise definition of an earthquake
A sudden and violent shaking of the ground caused by release of large amounts of energy
What major geological feature is created where tectonic plates move apart under the ocean?
Mid-ocean ridge.
what is the deepest part of the ocean and where is it located?
Challenger Deep in the Mariana Trench (deepest ocean point).
10,850 m (35,597 ft)
Deeper than Mt. Everest is tall
What type of plate boundary occurs where two plates move towards each other and one is fored beneath the other
Convergent boundary (subduction)
Name the primary rock types of the continental crust and the oceanic crust
Continental crust: mostly granite
Oceanic crust: basalt.
Which instrument records earthquakes and shows P-wave and S-wave arrivals?
Seismograph (seismogram records, showing P-wave and S-wave arrivals).
what type of crust is being created at divergent boundaries?
new oceanic crust
Which mountain is the highest above sea level and what is its elevation as given?
Mt. Everest — listed as 29,280 ft (8,848 m)29,280 ft (8,848 m) above sea level.
Describe what happens at a transform plate boundary, and give an example of what geologic phenomena would occur here.
Transform boundary: plates slide past one another; commonly causes shallow, frequent earthquakes (example: San Andreas Fault).
Identify which layer of the Earth is described as fluid with convection and explain in one sentence how convection in that layer affects plate motion.
Mantle — it behaves plastically and convects; mantle convection moves material and drives plate motion.
The largest recorded earthquake in history (Chile, May 22, 1960) had what Richter magnitude?
What were some impacts on humans?
Magnitude 9.5
about 2,000 killed and 2 million homeless
Approximately how long is the Mid-Atlantic ridge (in kilometers or miles)
16,000 km (10,000 miles)
Which mountain is tallest when measured from base to peak according to the document, and what is that height?
Mauna Kea — listed as 33,500 ft (10,210 m) from base to peak (taller from base than Everest).
Explain why mid-ocean ridges are associated with divergent plate boundaries and how this process contributes to sea-floor spreading.
Mid-ocean ridges form where plates diverge and mantle material upwells; new crust forms as magma cools, producing sea-floor spreading
What is the “Ring of Fire” and roughly what percentage of the world’s volcanoes are located there?
The Ring of Fire is the region around the Pacific with many volcanoes;
~75%
What type of plate boundary produces earthquakes at increasing depth? Provide a brief explanation of why the earthquake depths increase.
Subduction (Convergent)
Earthquakes happen at increasing depth as the subducting plate drags past the earth as it dives deep into the mantle.
What are some of the features associated with earthquakes found at mid ocean ridges?
shallow earthquakes
low-density earthquakes
Hotspot tracks form island chains as a plate moves over a fixed hotspot
Using plate types, state which combination of plates (oceanic or continental) commonly creates volcanic mountain chains through subduction, and briefly explain why melting occurs beneath the overriding plate.
An oceanic plate subducting beneath a continental plate.
Melting occurs because subducted oceanic crust gets pushed into the hot mantle which melts the plate
Explain why the Hawaiian Islands form a chain even though they are not on a plate boundary, and name the full chain name that includes the bend.
Hawaiian Islands form over a stationary mantle hotspot; as the Pacific Plate moves, new islands form in a line. The full chain including the bend is the Hawaiian-Emperor Chain (bend indicates a change in plate motion).
Explain how seismograph arrival times at multiple locations are used to locate an earthquake’s epicenter
Seismograph networks record differing arrival times of P-waves and S-waves; time differences give distance to the epicenter for each station. Triangulating distances from three or more stations locates the epicenter
How does sea-floor spreading explain the movement of continents over time?
For instance, how does the Mid-Atlantic ridge show that South America and Africa were once part of the same continent.
Compare and contrast the processes that create trenches (very deep oceanic features) and mid-ocean ridges, including where each forms relative to plate boundaries.
Trenches form at convergent boundaries where one plate subducts beneath another, producing very deep oceanic features. Mid-ocean ridges form at divergent boundaries where plates separate and new crust is created by upwelling magma