Caldera

26 Oct 2023 Caldera

This article covers “Daily Current Affairs” and the topic details “Caldera”. This topic has relevance in the Geography section of the UPSC CSE exam.

GS 1: Caldera

Why in the news?

Scientists at the California Institute of Technology (Caltech) have detected over 2,000 earthquakes occurring in the Long Valley Caldera in recent years.

About Long Valley Caldera:

• The Long Valley Caldera is a dormant supervolcano situated in the Eastern Sierra Nevada Mountains of California, USA. It was formed approximately 760,000 years ago by a super-eruption that expelled about 140 cubic miles of magma. This eruption blanketed much of east-central California with hot ash, which was even carried as far as what is now Nebraska.
• Since 1978, the caldera has been experiencing regular earthquake swarms, leading to concerns that it may be at risk of erupting again. Despite its dormant status, the ongoing seismic activity serves as a reminder of the caldera’s volatile past and potential future.

• Caldera definition: A caldera is a large, bowl-shaped depression formed by the collapse of a volcano after a massive eruption. It is the most destructive type of volcanic eruption. Calderas may have uneven shapes due to different rates of collapse.
• Caldera types: There are three main types of calderas, based on their formation and characteristics. They are:
  • Crater-lake calderas: These are formed by the collapse of a stratovolcano after a Plinian eruption, which is very explosive and releases huge amounts of lava, ash, and rocks. These calderas often fill with water, forming lakes.
  • Shield volcano calderas: These are formed by the gradual subsidence of a shield volcano due to the periodic release of lava. This is less explosive and produces fountains of lava. These calderas have nested or terraced shapes, rather than a single large depression.
  • Resurgent calderas: These are the largest and rarest type of calderas, formed by the widespread collapse of vast magma chambers due to extremely destructive eruptions called pyroclastic sheet flows. These eruptions have not occurred in historic times. These calderas may rise again due to magma pressure, forming domes or islands.

SOURCE: California’s supervolcano cooling down but may still cause quakes: Report

Download Yojna daily current affairs eng med 26th Oct 2023

Q.1 Consider the following statements:

1. Crater-lake calderas result from the collapse of stratovolcanoes .
2. Shield volcano calderas form gradually due to less explosive lava releases, creating nested or terraced depressions.

Which of the statements given above is/are correct? 

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

ANSWER: C

Q.2 Discuss the correlation between the distribution of volcanoes and earthquake belts. How do tectonic plate boundaries play a pivotal role in shaping these patterns?

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