Volcanic eruption explained - Steven Anderson

Summary

The script narrates the unexpected emergence of the Paricutin volcano in Mexico, triggered by geological forces. It explains how magma, influenced by lithostatic and magmastatic pressures, can lead to volcanic eruptions when the Earth's crust is unable to contain it. The role of dissolved gases in magma, the process of 'unloading', and the impact of climate change on volcanic activity are discussed. The script concludes by highlighting the challenges in predicting eruptions and the advancements in technology that may aid in understanding these natural phenomena.

Takeaways

• 🌋 The Paricutin volcano in Mexico was formed unexpectedly in 1942, starting as a fissure in a cornfield and eventually covering over 200 square kilometers with lava and ash.
• 🌍 The formation of any volcano begins with magma, which is molten rock that forms when ocean water infiltrates the Earth's mantle, lowering its melting point.
• 🔥 Magma typically remains underground due to a balance of lithostatic pressure, magmastatic pressure, and the rock strength of the Earth's crust.
• 💥 Eruptions can occur when this equilibrium is disrupted, often due to an increase in magmastatic pressure from dissolved elements and compounds forming high-pressure gas bubbles.
• 🎈 The presence of these gas bubbles can lower magma's density and increase its buoyancy, which may have been the trigger for the Paricutin eruption.
• 🌌 Two natural causes for the formation of buoyant bubbles are the influx of new magma from deeper underground and the cooling of magma, leading to the solidification of minerals and a concentration of dissolved gases.
• 🏔 Landslides or 'unloading' can also trigger eruptions by reducing the lithostatic pressure above a magma chamber, as seen in the 1980 Mount St. Helens eruption.
• ⛰ Erosion or melting glaciers can slowly unload pressure over time, with some geologists concerned that climate change-induced glacial melt could increase volcanic activity.
• 🗻 Eruptions can also happen when the rock layer weakens and can no longer contain the magma, due to processes like hydrothermal alteration or tectonic activity.
• 🔬 Predicting volcanic eruptions is challenging due to the difficulty in measuring changes in magmastatic pressure within deep and hot magma chambers.
• 🛠️ Technological advances like thermal imaging, spectrometers, and laser tracking are aiding volcanologists in better understanding and monitoring volcanic activity.

Q & A

What unusual event did Dionisio Pulido initially mistake for thunder in 1942?

Dionisio Pulido initially mistook the sound of a fissure opening in his cornfield, which later became known as the volcano Paricutin, for thunder.

How much area did the lava and ash from Paricutin cover over the years?

The lava and ash from Paricutin covered over 200 square kilometers over the next 9 years.

What is magma and where does it typically form?

Magma is molten rock that often forms in areas where ocean water can penetrate the Earth’s mantle, lowering the melting point of the layer.

What are the three geological factors that usually keep magma beneath the Earth's surface?

The three geological factors are lithostatic pressure (the weight of the Earth's crust), magmastatic pressure (magma pushing back against the crust), and the rock strength of the Earth's crust.

What causes an increase in magmastatic pressure?

An increase in magmastatic pressure can be caused by various elements and compounds in the magma, such as water or sulfur, that no longer dissolve and instead form high-pressure gas bubbles.

How do high-pressure gas bubbles in magma contribute to an eruption?

High-pressure gas bubbles can act like bubbles in a shaken soda, lowering the magma's density and increasing the buoyant force pushing upward through the crust, potentially leading to an explosive eruption.

What is the process behind the Paricutin eruption according to many geologists?

Many geologists believe that the Paricutin eruption was caused by the formation of buoyant bubbles in the magma, which increased the upward pressure through the crust.

What are the two known natural causes for the formation of buoyant bubbles in magma?

The two known natural causes for the formation of buoyant bubbles are the introduction of additional gassy compounds by new magma from deeper underground and the cooling of magma, which leads to the solidification of minerals and an increase in gas concentration.

What is the process called 'unloading' and how is it related to volcanic eruptions?

'Unloading' is the process where the weight of the rock above a magma chamber is significantly reduced, such as by landslides, which can drop lithostatic pressure and trigger an eruption.

How can climate change potentially increase volcanic activity?

Climate change can increase volcanic activity by causing glacial melt, which through the process of 'unloading', can reduce lithostatic pressure and potentially trigger eruptions.

What are some of the technological advances that volcanologists are using to better understand volcanoes?

Technological advances include thermal imaging to detect subterranean hotspots, spectrometers to analyze escaping gases, and lasers to track the impact of rising magma on a volcano's shape.

Why is predicting volcanic eruptions difficult despite understanding the causes?

Predicting volcanic eruptions is difficult because measuring changes in magmastatic pressure is challenging due to the depth and heat of magma chambers, making it hard to monitor the delicate balance of geological factors.