Geology of Indonesia and Tectonic Plates

Aug 14, 2024

Notes on Indonesia and Tectonic Plates

Introduction to the Ring of Fire

  • Indonesia is located in the Ring of Fire, a region around the Pacific Ocean known for:
    • Frequent earthquakes
    • Volcanic eruptions
  • The Ring of Fire forms a circle encircling the Pacific Ocean due to tectonic plate interactions.

Tectonic Plates Overview

  • Tectonic plates are large sections of the Earth's lithosphere that move and interact.
  • Earth’s lithosphere:
    • Rigid outer layer (about 100 km thick)
    • Composed of the crust and upper mantle
  • Below lithosphere: asthenosphere, which is solid but can flow very slowly.

Movement of Tectonic Plates

  • Plates move relative to each other at speeds of 2-15 cm/year.
  • Interaction of these plates leads to geological formations:
    • Himalayan mountains (Asia)
    • East African Rift
    • San Andreas Fault (California)
  • Developed between the 1950s to 1970s, updating the earlier theory of Continental Drift proposed by Alfred Wegener in 1912.

Tectonic Plates Surrounding Indonesia

  • Indonesia is surrounded by four tectonic plates:
    1. Indo-Australian Plate
      • Area: Approximately 58.9 million km²
      • Formed from the fusion of the Australian plate and Indian plate
      • Located in eastern regions like Papua and East Nusa Tenggara.
    2. Eurasian Plate
      • Area: Approximately 67.8 million km² (3rd largest in the world)
      • Includes most of Europe and Asia
      • Geological activity includes volcanic events and earthquakes in major Indonesian islands (Sumatra, Java, Sulawesi, Kalimantan).
    3. Pacific Plate
      • Area: Approximately 103.3 million km² (largest plate)
      • Located under the Pacific Ocean, influencing the formation of the Hawaiian Islands.
    4. Philippine Sea Plate
      • Area: Approximately 5.5 million km² (micro plate)
      • Located north of Halmahera and in contact with the other three macro plates.

Plate Movement and Geological Impact

  • Different movements of the plates:
    • Indo-Australian Plate: Moves northeast at 7.7 cm/year.
    • Pacific Plate: Moves northwest at 10.2 cm/year.
    • Eurasian Plate: Relatively stationary.
  • Resulting geological features and hazards:
    • Tectonic earthquakes
    • Volcanic activity from the northern tip of Sumatra to various islands in Indonesia.

Conclusion

  • Indonesia's unique geological features lead to a complex landscape:
    • Various beaches
    • Sea trenches
    • Active mountains
    • Faults
  • This complexity makes Indonesia prone to tectonic earthquakes, contributing to its identity as the largest archipelago in the world.

Closing

  • This presentation provides insights into Indonesia's geological dynamics and tectonic plates.
  • Thank you for watching!