Hawaii is well known to be a lush green paradise with abundant waterfalls, crystal clear oceans, and waves most of us can only dream of, but have you ever wondered how Hawaii formed?

The Hawaiian islands are the result of volcanic activity that began millions of years ago. Through a hotspot in the earth’s mantle, magma rose from the depths to form volcanoes. With the movement of the tectonic plate, a chain of these volcanoes formed, eventually known as the Hawaiian Islands.

Let’s explore the depths of the Hawaiian islands and the wonders that brought them to life.

Volcanoes and How They Form the Hawaiian Islands

The Hawaiian island chain is made of 137 islands, 8 of which are considered major islands. These 8 major islands are all shield volcanoes that have the characteristics of a broad shield shape with sides less steep than other volcanoes. 

We know Hawaii is a chain of volcanoes, but what exactly is a volcano, and how did it create Hawaii?

The Hawaiian islands began forming millions of years ago due to tectonic movement and volcanic activity
The Hawaiian islands began forming millions of years ago due to tectonic movement and volcanic activity

How Are Volcanoes Formed?

Volcanoes are formed in numerous ways, which depend on a variety of geological factors; however, 4 situations are the most common. 

These include:

  • Subduction Zones: One tectonic plate is pushed beneath another, which causes magma to rise to the surface
  • Hotspots: Areas of the Earth’s mantle that are hotter than others which causes magma to rise to the surface
  • Divergent Boundaries: Tectonic plates that move apart bring magma to the surface, which can form long chains of volcanic ridges and volcanoes with wide bases
  • Intraplate Volcanism: Not well-understood volcanic action that takes place away from tectonic boundaries

Although volcanoes form in a variety of ways, it is a volcanic hotspot that’s responsible for Hawaii.

Tectonic Plates: How Their Movement Creates Island Chains

Tectonic plates are massive pieces of the earth’s crust that float along the mantle. When these plates collide, they interact and cause a variety of results, such as colliding, pushing one down and the other up, they could move apart from each other, or sliding alongside each other.

The result that takes place depends on specific geological factors, but these plate interactions are often the causes of volcanic action and tsunamis.

Tectonic plates moving over volcanic hotspots in the ocean can result in island chains
Tectonic plates moving over volcanic hotspots in the ocean can result in island chains

In a volcanic situation, magma is pushed or raised to the top and spills out to form a volcano. Depending on the type of volcano and the viscosity of the magma, the volcano could erupt explosively or effusively.

As these plates move, older volcanoes drift away from the active location, and new volcanoes are formed in their place. Over millions of years, more volcanoes are formed and washed away, eventually forming an island chain.

What Are Volcanic Hotspots and How Did They Form Hawaii?

Volcanic hotspots, as mentioned above, are areas in the earth’s mantle where magma is hot enough to raise the level of magma to the surface.

This causes weak spots in the mantle where the magma spills out as tectonic plates move across it.

There are numerous volcanic hotspots that can be found around the globe
There are numerous volcanic hotspots that can be found around the globe

The rising magma forms a tube-like structure with sloping sides that slowly grow. This is what we see as a volcano.

As the tectonic plates move away from this hotspot, new volcanoes are formed, and those further away from the spot become dormant. It is through a hotspot and moving tectonic plates that the Hawaiian islands were formed.

Are the Hawaiian Islands Still Being Formed?

As the Hawaiian hotspot still exists, and the tectonic plates have not stopped moving, new islands are still being formed in the Hawaiian chain. However, this is an incredibly slow process that takes place over millions of years.

There are currently two active volcanoes on the Hawaiian chain which can both be found on the Big Island, often referred to as Hawai’i. Over time, the tectonic plates will move these volcanoes away from the hotspot, where they will become dormant.

As this process continues, new volcanoes will slowly be formed.

How Often Do the Hawaiian Islands Erupt?

Of the two active volcanoes in Hawaii, one is the largest volcano on Earth, and the other one of the most active.

The Hawaiian hotspot is still active and slowly forming new islands
The Hawaiian hotspot is still active and slowly forming new islands

Mauna Loa, the largest volcano on earth by volume, last erupted in 1984 and has since seen no activity, although it’s believed that this volcano will remain active for millions of years to come.

Kilauea, on the other hand, is one of the most active volcanoes on Earth and has been continuously erupting since 1983. This volcano also saw major volcanic action in 2018, where major changes to the landscape were made.


What makes the Hawaii islands unique?

The Hawaiian islands are unique for a number of reasons, some of which include their formation through a hotspot, whereas most other islands are formed on tectonic boundaries. Because of the island chain’s remote nature, it is also home to unique biodiversity and culture found nowhere else on Earth.

Apart from Hawaii, what other hotspots are there?

Geologists estimate that there are approximately 40 – 50 active volcanic hotspots on Earth. These hotspots are found in various sizes and have different geological effects on their surroundings. Some of the major volcanic hotspots include Hawaii, Yellowstone, East Africa, Galapagos Islands, and Iceland.

How has volcanic activity affected the Hawaiian Islands’ environment?

Volcanic activity around the Hawaiian islands has numerous impacts on the environment. Some of these include effects on air quality, a rise in tourism which in itself has numerous environmental effects, a change in water quality, as well as unique and isolated biodiversity and the constant change and formation of land.

When did the Hawaiian islands begin forming?

Kure Atoll is a coral atoll and also the oldest island of the Hawaiian chain. It’s believed that the island was formed over 30 million years ago and is also the most remote atoll in the world.

Of the major islands, Kauai is known to be the oldest of the eight and was formed approximately 5-5.5 million years ago. This volcano has been extinct for millions of years.

The youngest Hawaiian island is the Big Island, and is believed to continue to grow for millions of years to come.

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