Hawaii's Active Volcanoes

There are five volcanoes that are considered active in Hawaii. Maui has one of these volcanoes, called Haleakala, that could erupt again. It has not erupted in a long time but it has erupted at least ten eruptions in the past 1,000 years. There is an area southeast of Hawaii that has active volcanism and is called Lo'ihi. This is the site of the next Hawaiian Island.

The big island has three active volcanoes. The picture to the right shows the Big Island split into all five volcanoes and pictures Lo'ihi as well.The largest one is called Mauna Loa and this volcano is considered the largest single mountain in the world. On the top of Mauna Loa there is an oval caldera called Mokuaweoweo that is 4.8km long, 2.4km wide and 183 meters deep. The Mauna Loa can produce .9-4.5 million metric tons of lava per hour at the beginning of an eruption. Mauna Loa averaged about an eruption every 3.6 years between 1831 and 1950. Kilauea Volcano is a smaller volcano that is still active on the Big Island. It is located about 3,048km below the summit of Mauna Loa. The highest point or summit of Kilauea is 1,250m above sea level. Kilauea also has a caldera called Halemaumau meaning 'house of everlasting fire'. Hualalai is the third youngest and third most historically active volcano in Hawaii and is also located on the Big Island. Between 1700s and 1801 six different vents erupted from this volcano.

 The video below shows an ariel view of the Kilauea volcano erupting.

                                      



 Questions

You will need to use the links in the post and other resources. There are a list of helpful sites on the side of the blog.

1) Why do the Hawaiian islands form a chain? 

2) Why do hot spots occur?

3) What are several defining features of a shield volcano?

4) What are the locations (what island are they on) of the five active Hawaiian volcanoes?

5) Choose one of the five volcanoes and do a little more research on it. Find out at least: how big it is, the last time it erupted, what it's name means, and the oldest dated rocks.

The Formation of the Hawaiian Islands

Students, please read carefully through the information, watch the video, and answer the questions that follow (there are two posts). Bring your questions to class on Monday. If you have any questions ask them in the form of a comment and I will get back to you. Thank you and have fun!

The Hawaiian Islands are made up of large shield volcanoes that rise up out of the ocean. There is a geological 'hotspot' beneath the earth's crust that is currently underneath the Big Island. A hotspot is an area in the middle of a tectonic plate where volcanism occurs. Volcanism occurs in these areas because  magma is under pressure and is able to push its way to the surface.  Hot spots develop because of a weak or thin area in the plate.The force of the magma creates cracks in the earth's crust and these cracks get larger and larger as the magma wells up and creates a bulge. The force of the magma pushing up will eventually break through the cracks. When this happens runny lava oozes out and spreads around. The lava hardens when it comes into contact with the ocean water because the water is cold. This process happens over and over, thousands of times slowly building up more and more layers of magma until a large shield volcano is formed. First the volcano will form an undersea mountain but when the volcano reaches the surface of the ocean it creates a new island.

The Hawaiian Islands form a chain. This is because our earth's surface is made up of large tectonic plates that shift very slowly over time. The Hawaiian Islands are near the centre of the Pacific plate which slowly moving in a northwestern direction. Over millions of years this plate moves across the hot spot causing the original volcano to become extinct and creating a new volcano. As the older islands that are now extinct move away from the hot spot they no longer have volcanism and begin to erode. Kauai is the oldest of the islands and formed abut 5 million years ago and Oahu is the next oldest, both no longer have active volcanoes.