Mount Pinatubo Facts: Read About This Active Stratovolcano

Martha Martins
Nov 03, 2023 By Martha Martins
Originally Published on Mar 17, 2022
Mount Pinatubo facts are an interesting read.

Mount Pinatubo is a volcano with lava domes located around 55.9 mi (90 km) from northwestern Manila on Luzon Island in the Philippines.

The Mount Pinatubo eruption on June 15, 1991, was the first eruption in 600 years and the explosions peaked between June 14-16. However, based on recorded history, this eruption was on a smaller scale than the modern eruptive history of the volcano.

This volcano is seen as a modern-day example of extremely dangerous explosive eruptions in recent times. Mount Pinatubo is an active volcano, found on Zambales Mountains in Luzon Island's northern regions. Zambales Mountains are a part of the Luzon Island chain located between the complicated junctions of micro-plates between the Philippines and Eurasian plates.

Mount Pinatubo is a subduction-associated volcano and was formed by the movement of the Eurasian plate, which caused complete tectonic changes with the decreasing slab as it rose through the lithosphere of the Earth.

History Of Mount Pinatubo

Mount Pinatubo is a stratovolcano situated on Luzon, an island in the Philippines. The eruptive history of this volcano is split into two specific parts. The first portion of the history of this volcano concerns an ancestral volcano to Pinatubo. This specific period consists of all the eruptions of around 35,000 years ago.

The ancestral Pinatubo was made up of dacite and andesite; however, there is no solid evidence of the large eruptions from this volcano. Ancestral Pinatubo is believed to have been centered around the location of modern Pinatubo. This volcano is thought to have been as high as 7,550 ft (2301.2 m) above sea level at one time.

A 2.2 x 2.8 mi (3.5 x 4.5 km) wide caldera remains can be found from old Pinatubo even today. The oldest document eruption of Mount Pinatubo is believed to have been around 6,100 years ago.

Mount Pinatubo eruption ranks as the second-largest eruption of the 20th century, the first volcanic eruption being the Novarupta volcano in Alaska in 1912. Before its 1991 eruption, Pinatubo was unheard of because of its 400 years of dormancy. There were no recorded historic eruptions of the volcano.

Formation Of Mount Pinatubo

Mount Pinatubo was formed by the movement of the Eurasian plate under the Philippine Mobile Belt down the Manila Trench to the west of the region. This volcano grew in the subduction zone and has produced highly explosive or catastrophic eruptions in the past.

Geology Of Mount Pinatubo

Today, Pinatubo is a dome compound, a stratovolcano made up primarily of andesite and dacite. The structure is enveloped by sediment-laden and lahar (Indonesian term for a hot or cold mixture of rock fragments and water) deposits from the massive explosions of the volcano.

The eruptions of this volcano have been bunched into 6-12 eruptive periods. The events of June 15, 1991, are considered to be one of the smallest of the period.

Mount Pinatubo is situated in Cabusilan Mountain Range on Luzon, the largest and most populous island in the Philippines. This volcano is categorized as a stratovolcano, with towering, hilly sides made from layers of hardened lava, pumice, and volcanic ash.

The dust cloud from the eruption in 1991 covered an estimated 38610.2 sq mi (100,000 sq km) of Luzon Island, causing the region to fall into darkness.

Before its explosion, this volcano was discreet and had a deteriorated look. It was concealed under dense forest cover. Before the eruption, this volcano was 4,800 ft (1,463 m) tall, and today the volcano is around 4,900 ft (1493.5 m) tall.

Volcanologists have forecasted that the volcano will erupt shortly and the government have proposed various plans in case the volcano does explode in the near future.

Eruptions Of Mount Pinatubo

Pinatubo is believed to have undergone six periods of activity, with massive eruptions in the last 35,000 years. The 1991 eruption is ranked one of the smaller eruptions, and the largest is believed to have occurred 35,000 years ago, which presumably formed the caldera in the region.

Mount Pinatubo erupted on June 15, 1991, and caused a high-speed landslide of gas and hot ash, giant mudflows, and a volcano ash cloud that spread for more than 100 mi (160.9 km). Pinatubo eruption is known as the second-largest volcanic eruption of the 20th century.

The first magma from this eruption reached the exterior of the volcano between June 7 and 12. Since a large part of the gas within the magma was lost on its way to the exterior, this magma seeped out to create a lava dome.

However, this did not result in an explosion. Regardless, on June 12, the first spectacular eruption of this volcano occurred when gas-filled magma made its way to the surface.

The movement of this gas-filled magma to the exterior on June 15 caused a cataclysmic eruption that expelled more than 1 cubic mi (4.1 cubic km) of volcanic discharge. The volcanic ash cloud formed by this cataclysmic eruption ascended around 22 mi (35.4 km) into the air.

At lower altitude regions, the ash was spread to all regions by extreme cyclonic currents of a nearby forming typhoon. A shroud of volcanic smoke blanketed the country. The ash spread as far as the waters of the Indian Ocean and the smoke cloud was tracked by satellites.

The events caused huge landslides of pumice fragments, hot gas such as sulfur dioxide, and ash to roar down the sides of the volcano. The volcanic deposits are believed to have been around 660 ft (201.1 m) in thickness. The volcano's eruption caused the formation of a large caldera 1.6 mi (2.5 km) across.

A geological survey recorded occasional eruptions in September 1991. A lava dome formed in the new caldera from July to October 1992, as fresh magma ascended from beneath Pinatubo mountain.

The eruption of Mount Pinatubo resulted in the loss of 350 lives, most of the deaths caused by collapsing roofs. Various diseases broke out in evacuation camps and the continuous flow of ash caused additional deaths, taking the total death toll of the event to 722. More than 200,000 people were left homeless as a result of this eruption.

Aeta people, who inhabited the slopes of the mountain, were the worst affected group of people and were forced to flee from their homes. They found a destroyed village upon their return. Many of these people were successfully relocated by the Philippines government.

Currently, Mount Pinatubo is believed to be dormant, as it has not erupted since the 1991 eruption. The United States Geological Survey and the Philippine Institute of Volcanology and Seismology predicted the climactic eruption of Pinatubo in 1991, leading to the protection of at least 5,000 lives and prevented damage to at least $250 million in possessions.

Commercial and non-commercial aircraft flying in the region were cautioned about the dangers of the ash cloud formed from the June 15 eruption. Although most of the equipment was saved, the aftermath of the eruption destroyed two of the largest US military bases in the county.

The eruption of the volcano is estimated to have released a few million tons of sulfur dioxide into the stratosphere of the planet. The distribution of these gas clouds around the planet impacted the global climate and the global temperature dropped by around 1 degree from 1991-1993.

This eruption caused massive damage to the agriculture of the region as various sugar cane and rice paddies were buried under volcanic ash, which turned the soil unfit for agriculture.

Did You Know...

Even more than five years after the 1991 Mount Pinatubo eruption, the cataclysmic eruption of the volcano continued. Ash deposits from this eruption filled the surrounding regions and caused climatic change on a global scale.

Since 1991, these regions have seen an increase in typhoon rains, which formed giant mudflows after coming in contact with the volcanic residues.

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported a small phreatic explosion at Pinatubo on November 30, 2021. The event is believed by the geological survey to be a result of shallow hydrothermal processes on the low seismic activity recorded on the previous days. The eruption of Mount Pinatubo created Lake Pinatubo, a crater lake.


How was Mount Pinatubo formed?

Mount Pinatubo was formed as a result of the Eurasian plate sliding under the Manila Trench.

What caused Mount Pinatubo to erupt?

Small earthquakes formed under the volcano due to magma rising towards the surface. These earthquakes generated strong steam explosions, causing the volcano to erupt.

What type of volcano is Mount Pinatubo?

Mount Pinatubo is a stratovolcano. A stratovolcano is referred to as a conical-shaped volcano created by several layers of lava and ash.

Why is Mount Pinatubo famous?

Mount Pinatubo is famous for its VEI-6 eruption of 1991. The explosive eruption is known to be the second-largest terrestrial volcanic explosion of the 20th century.

Has Mount Pinatubo killed anyone?

The 1991 Mount Pinatubo eruption killed an estimated 350 people. However, massive damage to lives and property was prevented due to the prediction of this event.

Why is it called Mount Pinatubo?

The word 'pinatubo' translates to 'to have made grow' in the Sambal and Tagalog languages. The name suggests a knowledge of the volcano's eruption in 1500 AD.

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Written by Martha Martins

Bachelor of Arts specializing in Linguistics

Martha Martins picture

Martha MartinsBachelor of Arts specializing in Linguistics

Martha is a full-time creative writer, content strategist, and aspiring screenwriter who communicates complex thoughts and ideas effectively. She has completed her Bachelor's in Linguistics from Nasarawa State University. As an enthusiast of public relations and communication, Martha is well-prepared to substantially impact your organization as your next content writer and strategist. Her dedication to her craft and commitment to delivering high-quality work enables her to create compelling content that resonates with audiences.

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