Study Guide Questions Flashcards
How did Kant conceive the cause of earthquakes
Air through tunnels under the Earth force it around.
- The eruption of what volcano caused the year without a summer? How much did temperatures drop in western Europe?
The eruption of Mount Tambora in 1815 caused the year without a summer, and temperatures dropped by about 1.5 to 2.5 degrees Celsius in western Europe.
- What were the maximum tsunami run-up heights caused by the great Japan earthquake and the Lake Lituya events?
40.5m for Japan, and 524m for Lake Lituya
- How were natural hazards coupled in the Lake Lituya event?
o Give an example of hazard coupling for another (not Lake Lituya) event.
Another example of hazard coupling is the 2004 Indian Ocean earthquake and tsunami, where the underwater earthquake triggered a devastating tsunami that resulted in widespread destruction and loss of life in coastal regions across multiple countries.
o 1994 Northridge EQ vs 2003 Bam EQ
In the 1994 Northridge earthquake, the primary hazard was the seismic shaking caused by the rupture of the San Andreas Fault in California, leading to widespread damage to buildings and infrastructure. In contrast, the 2003 Bam earthquake in Iran was primarily characterized by the collapse of poorly constructed adobe buildings due to intense ground shaking, resulting in significant casualties and destruction in the city of Bam.
- Name 2 map projections.
Mercator, Gall-Peters
- Marie Tharp and the mapping of the seafloor
Marie Tharp played a crucial role in mapping the seafloor by meticulously analyzing and plotting data collected from sonar soundings, which led to the creation of the first comprehensive maps of the ocean floor, revealing the mid-ocean ridges and other key features of Earth’s underwater topography.
- Structure of the Earth
o Seismic tomography –
Waves travel more quickly in denser materials and slower in loose material
S-waves can’t travel through fluids (proof of liquid outer core)
- Evidence for plate tectonics (and continental drift)
Evidence for plate tectonics and continental drift includes the fit of continents like South America and Africa, matching geological formations and fossils across continents, magnetic striping on the ocean floor, and the distribution of earthquakes and volcanoes along plate boundaries.
- Ocean basins – images of the seafloor, seafloor ages, etc.
Ocean basins feature diverse seafloor landscapes, including abyssal plains, mid-ocean ridges, and deep-sea trenches. Seafloor age is determined through techniques like marine magnetic anomalies, revealing younger crust near mid-ocean ridges and older crust near continents.
Magnetization – Explain how the observed magnetic patterns provide evidence for seafloor spreading
As new oceanic crust forms at mid-ocean ridges, iron-bearing minerals in the magma align with Earth’s magnetic field, creating alternating bands of normal and reversed polarity that symmetrically mirror each other on either side of the ridge.
- Hotspots – Explain how island chains are formed and how this is related to plate tectonics
Island chains form from volcanic activity at hotspots beneath Earth’s crust. As tectonic plates move over these stationary hotspots, successive volcanic eruptions create chains of islands. This process provides evidence for plate tectonics by demonstrating the interaction between tectonic plates and volcanic activity.
- Explain what happens in terms of the Earth’s lithosphere (i.e. created or destroyed or otherwise) at
o Convergent margins
o Divergent margins
o Transform plate boundaries
Convergent: destroyed. Divergent: created. Transform: nothing
Isostasy
Isostasy is the balance of forces that determines the vertical movements of Earth’s crust in response to changes in the distribution of mass, such as the loading and unloading of glaciers or the formation of mountain ranges.
o Types of faults
Normal (div.), Thrust/Reverse (conv.), Strike-Slip (Transform)
What causes a fault to slip?
Faults slip due to the accumulation of stress along their boundaries caused by tectonic forces, such as compression, tension, or shear. When the stress exceeds the strength of the rocks holding the fault in place, it ruptures, causing the rocks to move along the fault plane, releasing energy in the form of an earthquake.
o Earthquake cycle (interseismic, coseismic)
The earthquake cycle involves two main phases: interseismic and coseismic. During the interseismic phase, strain accumulates along a fault due to tectonic forces, causing gradual deformation. When the accumulated stress exceeds the strength of the rocks, the fault slips suddenly during the coseismic phase, generating an earthquake and releasing the accumulated strain energy.
Types of Waves
Primary waves (P-waves): Fastest seismic waves that propagate through solids, liquids, and gases. They cause minimal damage but can still shake structures.
Secondary waves (S-waves): Slower than P-waves, S-waves only travel through solids. They cause moderate damage and shake structures side to side.
Surface waves: Slower than P and S-waves, surface waves only travel along Earth’s surface. They include Love waves, which move side to side, and Rayleigh waves, which have a rolling motion. Surface waves cause the most damage to structures and the ground.
Focus / Hypocenter vs. Epicenter
The focus (hypocenter) of an earthquake is the point within the Earth where the rupture initiates and seismic waves originate. The epicenter is the point on the Earth’s surface directly above the focus where the earthquake’s effects are usually strongest.
Seismograms and seismographs
Seismographs are instruments that detect and record seismic waves generated by earthquakes. Seismograms are the graphical representations or records produced by seismographs, showing the amplitude and arrival times of seismic waves, which help scientists analyze earthquake characteristics such as magnitude, location, and depth.
