Distribution of earthquakes and tsunamis

• What are the types of plate margins associated with earthquakes and volcanoes?

  Constructive, destructive, conservative, collision
• Where do most earthquakes occur?

  Along plate boundaries, especially subduction zones
• Which tectonic plates are associated with destructive margins?

  Nazca and South American plates
• Which tectonic plates are associated with collision margins?

  Indo-Australian and Eurasian plates
• What is the relationship between earthquakes and linear patterns?

  Most earthquakes occur in linear patterns at subduction zones
• What percentage of earthquakes occur on the Ring of Fire?

  90%
• Where do most volcanoes occur?

  Along plate boundaries, especially in the Pacific Ring of Fire
• What fraction of the world's volcanoes are found in the Pacific Ring of Fire?

  ¾
• What type of lava do most volcanoes produce?

  Molten magma that supplies the volcanoes
• How do subduction zones relate to volcano formation?

  They create volcanic chains called island arcs
• What geological feature is created by the subduction of the Nazca plate?

  Fold mountains like the Andes
• What type of eruptions are produced by subduction-related volcanoes?

  Viscous lava, explosive eruptions, and ash
• What happens to an oceanic plate as it subducts?

  It warms and releases volatile compounds
• What occurs when water meets hot rock during an eruption?

  Huge explosions due to vaporization
• What happens to gas in rising magma?

  Pressure drops, forming bubbles
• What type of lava do isolated volcanoes like the Hawaiian Islands produce?

  Basaltic lava
• How are isolated volcanoes formed?

  By hotspots or magma plumes beneath plates
• What is the process of volcano formation at convergent margins?

  Oceanic plate subducts, creating magma chambers
• What are the steps in the formation of volcanoes at convergent margins?

  1. Denser oceanic plate subducts beneath continental crust
  2. Heat melts the edge of the plate, forming a magma chamber
  3. Magma chamber contains dissolved gases and sea bed materials
  4. Friction creates faults, allowing magma to rise
  5. Increased pressure forces magma through the central vent
  6. Eruptions may occur through secondary cones if the vent is blocked
• What are the steps in the formation of volcanoes at divergent margins?

  1. Plates move apart at divergent margins
  2. Magma rises to the surface, reducing pressure
  3. Basic lava emerges from fissures
  4. Produces mainly shield volcanoes with less frequent eruptions
• Where do most tsunamis occur?

  In the Pacific Ocean
• What triggers most tsunamis?

  Earthquakes, sometimes volcanic eruptions or landslides
• Why do tsunamis predominantly occur in the Pacific Ocean?

  Due to subduction zones at Pacific plates