The Big One: Historic Earthquakes, Volcanoes, Tsunamis

Overview

Plate tectonics is the driving force behind earthquakes, volcanoes, and tsunamis. The Earth's lithosphere is broken into plates that move and interact at their boundaries. These interactions, such as collisions (subduction zones) or sliding past each other (transform boundaries), generate stress. When this stress is released, it causes earthquakes. Subduction zones, where one plate slides beneath another, are also associated with volcanic activity as the subducting plate melts and the resulting magma rises to the surface. Finally, large earthquakes, particularly those occurring on or near the ocean floor, can displace the seabed, generating tsunamis. 1. Plate Boundaries and Interactions: a. Divergent Boundaries: Where plates move apart, magma rises to the surface, creating new crust and causing volcanic activity, often in the form of mid-ocean ridges. Earthquakes at these boundaries tend to be shallow and less powerful. b. Convergent Boundaries: Where plates collide, one plate can be forced beneath the other (subduction). This process generates magma, leading to explosive volcanic eruptions and powerful earthquakes, particularly where the subducting plate melts and releases magma. The "Ring of Fire" around the Pacific Ocean is a prime example of this. c. Transform Boundaries: Where plates slide past each other horizontally, friction builds up until it's released as an earthquake. These earthquakes can be powerful and are often shallow. 2. Earthquakes and Plate Tectonics: Earthquakes occur along fault lines, which are fractures in the Earth's crust where plates meet. As plates move, they can get stuck, causing pressure to build. When the pressure exceeds the strength of the rocks, the plates slip, releasing energy as seismic waves, which we feel as earthquakes. The depth and intensity of earthquakes vary depending on the type of plate boundary and the specific geological setting. 3. Volcanoes and Plate Tectonics: Volcanoes are often found at plate boundaries, particularly at convergent boundaries where one plate subducts. The subducting plate melts, and the resulting magma rises to the surface, causing volcanic eruptions. Divergent boundaries also experience volcanic activity as magma rises to fill the space between separating plates. Volcanoes can also be found at hotspots, which are areas of volcanic activity not directly related to plate boundaries. 4. The Ring of Fire: The Ring of Fire is a zone of intense seismic and volcanic activity that circles the Pacific Ocean. It is a prime example of how plate tectonics drives these phenomena, as it is located at a convergence zone where the Pacific Plate is subducting beneath surrounding plates. 5. Tsunamis and Plate Tectonics: Tsunamis are large ocean waves often triggered by underwater earthquakes or volcanic eruptions. Large vertical displacements of the ocean floor, caused by these events, displace massive amounts of water, generating these destructive waves.

Suggested Media

Age 8 and up

Web Resources: Plate Tectonics

Plate tectonics is the theory that the Earth's lithosphere (the crust and upper mantle) is divided into several plates that move and interact with each other. These plates “float” on the semi-molten asthenosphere below, and their movements cause geological phenomena like earthquakes, volcanic eruptions, and the formation of mountains. https://education.nationalgeographic.org/resource/plate-tectonics/
• VIDEO: TECTONIC PLATES (Excellent introduction): https://www.youtube.com/watch?v=Kg_UBLFUpYQ• VIDEO: PLATE TECTONICS: https://www.youtube.com/watch?v=JmC-vjQGSNM• VIDEO: PLATE TECTONICS (Oregon/California): https://www.youtube.com/watch?v=2TSTVCIZ-dg • VIDEO: PLATE TECTONICS (IRIS: Incorporated Research Institutions for Seismology): https://www.youtube.com/watch?v=Xzpk9110Lyw• PLATE TECTONICS: https://www.livescience.com/37706-what-is-plate-tectonics.html• PLATE TECTONICS: https://www.britannica.com/science/plate-tectonics• PLATE TECTONICS: https://www.geolsoc.org.uk/Plate-Tectonics/Chap2-What-is-a-Plate

Web Resources: Earthquakes

An earthquake is the shaking or trembling of the Earth's crust caused by the sudden release of energy, often due to the movement of tectonic plates. This movement can occur along fault lines, where the Earth's crust is broken and the blocks on either side move relative to each other. The energy released travels outwards as seismic waves, causing the ground to shake. https://en.wikipedia.org/wiki/Earthquake#:
AND FOR SOME FUN: Annie & the Natural Wonder Band: https://www.youtube.com/watch?v=cJeGP5qRCNs
Lisbon 1755
Krakatau 1883

Web Resources: Volcanoes

A volcano is a vent or fissure in the Earth's crust (or another planet's surface) through which molten rock (magma), ash, and gases erupt. Volcanoes can also refer to the landform created by the accumulation of erupted materials, often cone-shaped. https://spaceplace.nasa.gov/volcanoes2/en/#
• VIDEO: VOLCANOES (National Geographic): https://www.youtube.com/watch?v=yDy28QtdYJY• VIDEO: VOLCANO TYPES (PBS Nova): https://www.youtube.com/watch?v=HdhARb2PGqA• VIDEO: YELLOWSTONE SUPERVOLCANO: https://www.youtube.com/watch?v=lMLo0E66O8A• VIDEO: TYPES OF VOLCANOES: https://www.youtube.com/watch?v=WgktM2luLok• WHAT CAUSES VOLCANOES: https://www.scientificamerican.com/article/what-causes-a-volcano-to/• VOLCANOES (National Geographic): https://www.nationalgeographic.com/environment/natural-disasters/volcanoes/

Web Resources: Tsunamis

A tsunami is a series of powerful ocean waves typically caused by large-scale disturbances like underwater earthquakes, volcanic eruptions, or landslides. These waves, with long wavelengths and periods, can travel vast distances across oceans and cause significant destruction when they reach coastal areas. https://en.wikipedia.org/wiki/Tsunami#

Web Resources: Preparedness

Predictions

As of today, there's no completely accurate way to predict exactly when an earthquake (and its possible tsunami) or volcano will occur. But there’s a lot of cutting-edge science taking place that makes it possible to make “educated” assumptions and guesses. More than ever, speaking in terms of “probabilities” is far more a reality than it was a decade ago. As time goes on, and more pioneering discoveries are made, accurate predictions may become more than a mere possibility. Here are some resources that examine what’s currently happening in volcanology, seismology, and oceanography.
• NEW SCIENTIST: https://www.newscientist.com/article/mg19926752-000-unknown-earth-can-we-predict-earthquakes-and-volcanic-eruptions/• FUTURISM: https://futurism.com/satellites-will-soon-predict-earthquakes-and-volcanic-eruptions-from-space/• CARNEGIE INSTITUTE SCIENCE: https://carnegiescience.edu/news/how-can-we-predict-volcanoes-and-earthquakes• VOX: https://www.vox.com/energy-and-environment/2017/9/21/16339522/8-things-to-know-about-earthquakes-alaska• SMITHSONIAN MAGAZINE: https://www.smithsonianmag.com/smart-news/does-earths-molten-core-power-earthquake-cycle-180967054/• QUARTZ: https://qz.com/1188262/volcano-eruption-prediction-methods-scientists-say-crystals-can-tell-when-a-volcano-will-blow/• SCIENTIFIC AMERICAN: https://www.scientificamerican.com/article/volcano-forecast-new-technique-could-better-predict-eruptions/• PACIFIC NORTHWEST SEISMIC NETWORK: https://pnsn.org/outreach/faq/earthquake-prediction

Pacific Northwest