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# Plate Boundaries and Related Phenomena This document describes different types of plate boundaries, their characteristics, and the associated phenomena. ## Divergent Plate Boundary * **Causes:** Upwelling magma, forming new crust. * **Oceanic:** Creates mid-ocean ridges and undersea mountains (...

# Plate Boundaries and Related Phenomena This document describes different types of plate boundaries, their characteristics, and the associated phenomena. ## Divergent Plate Boundary * **Causes:** Upwelling magma, forming new crust. * **Oceanic:** Creates mid-ocean ridges and undersea mountains (e.g. African Rift Valley, Iceland). * **Continental:** Creates rifts in the land (e.g. African Rift Valley). * **Effect:** Spreading of tectonic plates, volcanic activity, formation of new crust. * **Tsunami formation** - Rapid movement of ocean floor due to divergent plate activity causes waves, whose height increases as they reach shallow water. ## Transform Plate Boundary * **Description:** Plates slide past each other. * **Effect:** Tension builds, resulting in earthquakes. (Example: San Andreas fault). * **Note:** Seismic activity and potential tsunamis - Underwater fault slips, releases energy, causing large waves. ## Convergent Plate Boundary * **Description:** Plates collide. * **Types:** Subduction and collision. * **Subduction** results in a destructive process, one plate being forced under another. * **Collision** results in a constructive process, two plates colliding and building up landforms. * **Effects:** Earthquakes, volcanic activity (volcanic arcs), trench formation. ## Earthquakes * **Mechanism:** Fault lines lock up, building stress. When plates move, the energy is released causing the Earth to shake. * **Measurement:** SEISMOGRAPH uses the Richter scale. * **Tsunamis:** Earthquakes can cause underwater fault slips, releasing energy that generates tsunami waves. ## Volcanoes * **Mechanism:** Rupture in the lithosphere, allowing magma from the asthenosphere to reach the Earth's surface. * **Location:** Common at convergent subduction zones, divergent plate boundaries, and hot spots. * **Types of Eruptions:** Can vary from mild to deadly, emitting gases (water vapor, carbon dioxide, sulfur dioxide) and ejecta (ash, rocks, Magma). * **Aftermath:** Ash, particulates from eruptions can block sunlight and decrease global temperatures for 1-3 years (by blocking sunlight, affecting photosynthesis and decreasing global temperatures for a few years). Sulfur dioxide may cause global cooling as it turns into aerosols that block radiation to reach Earth. ## Diagram of Plate Boundaries The document includes diagrams illustrating the different types of plate boundaries—divergent (plates moving apart), convergent (plates colliding), and transform (plates sliding past each other) showing the relationship with topography, the formation of new landmasses and ocean trenches, and the associated volcanic activity and earthquakes. The diagrams also show how the plates move and interact with each other. A further labelled diagram illustrates how a tsunami is formed. ## Additional Factors and Effects * **Global effects:** Ashfall, and disruptions to global supply chains. * **Time-frame:** Devastation and climate effects are described in the different time frames from hours to years and climate impacts and global chain disruptions.