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.

Outlines

00:00

🌋 Birth of Paricutin: Unpredictable Eruption Mystery

In 1942, Dionisio Pulido discovered a new volcano, Paricutin, in his cornfield, Mexico, which intrigued scientists with its sudden emergence. The script delves into the origins of volcanoes, starting with magma formation influenced by ocean water penetrating the Earth's mantle. It explains the balance of lithostatic, magmastatic pressures, and rock strength that usually contain magma beneath the surface. The eruption of Paricutin is hypothesized to be due to an increase in magmastatic pressure from dissolved elements forming gas bubbles, which, when reaching the surface, can cause explosive eruptions. The script also discusses other triggers for volcanic activity, such as 'unloading' from landslides or glacial melt, and the weakening of rock layers by hydrothermal alteration and tectonic activity.

05:02

🔬 Volcanic Eruptions: The Quest for Prediction

This paragraph continues the exploration of volcanic activity, focusing on the difficulty of predicting eruptions. Despite understanding the geological factors that contribute to volcanic eruptions, measuring changes in magmastatic pressure remains a challenge due to the depth and heat of magma chambers. The script highlights the ongoing efforts of volcanologists to develop new technologies for better understanding and monitoring of volcanic activity. Advances in thermal imaging, spectrometry for gas analysis, and laser tracking for volcanic shape changes are mentioned as tools that may enhance our ability to anticipate and study volcanic eruptions.

Keywords

💡Paricutin

Paricutin is the name of a volcano that emerged in a Mexican cornfield in 1942, as described in the script. It is a key example illustrating the spontaneous formation of a volcano. The script details how this new volcano's eruption was a result of geological processes, making it central to the video's theme of volcanic eruptions and their causes.

💡Magma

Magma is molten rock found beneath the Earth's surface, which plays a fundamental role in the formation of volcanoes. The script explains that the presence of magma is the starting point of any volcanic activity. It is the driving force behind eruptions, as it can exert pressure that may lead to explosive events, such as the one that created the Paricutin volcano.

💡Lithostatic Pressure

Lithostatic pressure is the weight of the Earth's crust pressing down on the magma. The script describes it as one of the three geological factors that maintain a delicate balance to keep magma beneath the surface. When this pressure is disrupted, it can lead to volcanic eruptions, highlighting its importance in understanding volcanic activity.

💡Magmastatic Pressure

Magmastatic pressure is the force exerted by magma pushing back against the lithostatic pressure. The script uses this term to explain how magma can create an upward pressure that, if not balanced, can result in volcanic eruptions. It is a critical concept in the video's exploration of the dynamics between the Earth's crust and the magma beneath it.

💡Rock Strength

Rock strength refers to the durability and resistance of the Earth's crust. In the script, it is identified as the third factor in the balance that keeps magma in check. The strength of the rock can determine whether it can withstand the pressures from below, and its weakening can be a precursor to volcanic eruptions.

💡Eruption

An eruption is a geological event where magma, ash, and gases are expelled from a volcano. The script discusses various triggers for eruptions, such as changes in pressure and the weakening of the Earth's crust. The term is central to the video's narrative, as it describes the explosive outcome of the geological processes discussed.

💡Buoyant Force

Buoyant force is the upward push that acts on objects in a fluid or gas. In the context of the script, it is used to describe how the formation of gas bubbles in magma can decrease its density and increase the force that pushes it upward through the crust, potentially leading to an eruption.

💡Hydrothermal Alteration

Hydrothermal alteration is a process where acidic gases and heat from magma corrode rock, turning it into soft clay. The script mentions this as a way the rock layer can be weakened, allowing magma to rise and potentially cause an eruption. It is an important concept in understanding how volcanic activity can be facilitated by the alteration of the Earth's crust.

💡Tectonic Activity

Tectonic activity refers to the movement of the Earth's plates, which can create fissures and stretch the crust. The script explains that such activity can weaken the rock layer, making it susceptible to volcanic eruptions. It is a key concept in the video's discussion of the various factors that can trigger eruptions.

💡Volcanologists

Volcanologists are scientists who study volcanoes and volcanic activity. The script mentions their efforts to understand and predict volcanic eruptions through the use of technology and scientific methods. They are central to the video's message about the ongoing quest to better comprehend and potentially predict volcanic activity.

💡Spectrometer

A spectrometer is a device used to measure properties of light over a specific portion of the electromagnetic spectrum. In the script, it is mentioned as one of the tools volcanologists use to analyze gases escaping from magma, aiding in the study of volcanic activity. It exemplifies the scientific advancements that contribute to our understanding of volcanoes.

Highlights

In 1942, a new volcano named Paricutin emerged in Mexico, surprising locals with its sudden appearance and explosive eruptions.

The formation of any volcano begins with magma, influenced by the interaction between ocean water and the Earth's mantle.

Magma typically remains underground due to a balance of lithostatic, magmastatic pressures, and the rock strength of the Earth’s crust.

Volcanic eruptions can be triggered when the equilibrium between these geological factors is disrupted.

An increase in magmastatic pressure, often due to the formation of high-pressure gas bubbles, can lead to explosive eruptions.

Geologists believe that the Paricutin eruption was likely caused by the buoyant force of gas bubbles within the magma.

Two natural causes for the formation of buoyant bubbles in magma are the introduction of new magma from deeper underground and the cooling process of magma solidifying into crystals.

Landslides or 'unloading' can significantly reduce lithostatic pressure, leading to volcanic eruptions like the 1980 Mount St. Helens event.

Erosion and melting glaciers can also cause 'unloading' over longer periods, potentially increasing volcanic activity.

Climate change and glacial melt are of concern to geologists due to their potential to affect volcanic activity.

The weakening of the rock layer by acidic gases and hydrothermal alteration can also result in volcanic eruptions.

Tectonic activity, such as earthquakes and continental plate shifts, can create pathways for magma to reach the surface.

Predicting volcanic eruptions is challenging due to the difficulty in measuring changes in magmastatic pressure.

Advances in thermal imaging, spectrometry, and laser technology are aiding volcanologists in better understanding and monitoring volcanic activity.

Volcanologists are utilizing new technologies to detect subterranean hotspots and analyze escaping gases from magma.

Lasers are used to track the impact of rising magma on a volcano’s shape, providing insights into potential eruptions.

The ongoing exploration of new technology aims to improve our understanding of volcanic vents and their explosive nature.

Transcripts

In February of 1942, Mexican farmer Dionisio Pulido

thought he heard thunder coming from his cornfield.

However, the sound wasn’t coming from the sky.

The source was a large, smoking crack emitting gas and ejecting rocks.

This fissure would come to be known as the volcano Paricutin,

and over the next 9 years, its lava and ash would cover over 200 square km.

But where did this new volcano come from,

and what triggered its unpredictable eruption?

The story of any volcano begins with magma.

Often, this molten rock forms in areas where ocean water

is able to slip into the Earth’s mantle and lower the layer’s melting point.

The resulting magma typically remains under the Earth’s surface

thanks to the delicate balance of three geological factors.

The first is lithostatic pressure.

This is the weight of the Earth’s crust pushing down on the magma below.

Magma pushes back with the second factor, magmastatic pressure.

The battle between these forces strains the third factor:

the rock strength of the Earth’s crust.

Usually, the rock is strong enough and heavy enough

to keep the magma in place.

But when this equilibrium is thrown off, the consequences can be explosive.

One of the most common causes of an eruption

is an increase in magmastatic pressure.

Magma contains various elements and compounds,

many of which are dissolved in the molten rock.

At high enough concentrations, compounds like water or sulfur no longer dissolve,

and instead form high-pressure gas bubbles.

When these bubbles reach the surface,

they can burst with the force of a gunshot.

And when millions of bubbles explode simultaneously,

the energy can send plumes of ash into the stratosphere.

But before they pop, they act like bubbles of C02 in a shaken soda.

Their presence lowers the magma’s density,

and increases the buoyant force pushing upward through the crust.

Many geologists believe this process was behind the Paricutin eruption

in Mexico.

There are two known natural causes for these buoyant bubbles.

Sometimes, new magma from deeper underground

brings additional gassy compounds into the mix.

But bubbles can also form when magma begins to cool.

In its molten state, magma is a mixture of dissolved gases and melted minerals.

As the molten rock hardens, some of those minerals solidify into crystals.

This process doesn’t incorporate many of the dissolved gasses,

resulting in a higher concentration of the compounds

that form explosive bubbles.

Not all eruptions are due to rising magmastatic pressure—

sometimes the weight of the rock above can become dangerously low.

Landslides can remove massive quantities of rock from atop a magma chamber,

dropping the lithostatic pressure and instantly triggering an eruption.

This process is known as “unloading”

and it’s been responsible for numerous eruptions,

including the sudden explosion of Mount St. Helens in 1980.

But unloading can also happen over longer periods of time

due to erosion or melting glaciers.

In fact, many geologists are worried that glacial melt

caused by climate change could increase volcanic activity.

Finally, eruptions can occur when the rock layer is no longer strong enough

to hold back the magma below.

Acidic gases and heat escaping from magma

can corrode rock through a process called hydrothermal alteration,

gradually turning hard stone into soft clay.

The rock layer could also be weakened by tectonic activity.

Earthquakes can create fissures allowing magma to escape to the surface,

and the Earth’s crust can be stretched thin

as continental plates shift away from each other.

Unfortunately, knowing what causes eruptions

doesn’t make them easy to predict.

While scientists can roughly determine the strength and weight

of the Earth’s crust,

the depth and heat of magma chambers makes measuring changes

in magmastatic pressure very difficult.

But volcanologists are constantly exploring new technology

to conquer this rocky terrain.

Advances in thermal imaging have allowed scientists

to detect subterranean hotspots.

Spectrometers can analyze gases escaping magma.

And lasers can precisely track the impact of rising magma on a volcano’s shape.

Hopefully, these tools will help us better understand these volatile vents

and their explosive eruptions.