Long Valley Caldera

Oct. 25, 2023

More than 2,000 earthquakes have been identified rumbling across the Long Valley Caldera in the last few years by scientists at the California Institute of Technology (Caltech).

About Long Valley Caldera:

It is located in the Eastern Sierra Nevada Mountains of California, United States of America (USA).
It is a dormant supervolcano.
It was formed by a super-eruption about 760,000 years ago that blasted 140 cubic miles of magma, covering much of east-central California in hot ash that was blown as far away as present-day Nebraska.
It has been unleashing earthquake swarms on a regular basis since 1978, raising concerns that it might be at risk of erupting.

What is Caldera?

It is a depression created after a volcano releases the majority of the contents of its magma chamber in an explosive eruption.
Without any structural support below, the land around the erupting volcanic vent or vents collapses inwardly, creating the bowl-shaped caldera.
A caldera-causing eruption is the most devastating type of volcanic eruption.
These are formed by the inward collapse of a volcano.
Calderas may have parts of their sides missing because land collapses unevenly.
Types of Calderas
- Crater-Lake Calderas: It is a result from the collapse of a stratovolcano after a Plinian eruption, the most explosive type of volcanic eruption.
- Plinian eruptions release massive amounts of lava, volcanic ash, and rocks.
- Shield Volcano Calderas: These calderas do not result from singular explosive eruptions.
- They instead subside in gradual stages, due to the episodic release of lava. This less-explosive release of lava, known as lava fountaining, is characteristic of shield volcanoes.
- As a shield volcano periodically releases lava, it produces nested or terraced depressions rather than a large bowl-shaped caldera.
- It is composed of dormant and active shield volcanoes.
- Resurgent Calderas: These are the largest volcanic structures on Earth.
- They are not associated with one particular volcano, but instead result from the widespread collapse of vast magma chambers.
- This caldera collapse is produced by incredibly destructive eruptions known as pyroclastic sheet flows, the likes of which have not occurred in historic times.