December 2022

Mauna Loa Erupts


Mauna Loa erupts on November 27, 2022.

During the night of November 27, the Mauna Loa volcano on the island of Hawaii erupted. The last time it erupted was nearly 40 years ago. Mauna Loa is the world’s largest active volcano. An active volcano is one that is erupting or is likely to in the future.

A volcano is a place on earth’s surface where hot gasses and molten rock from deep inside the earth are released. Because temperatures inside the earth are so high, some rock is molten, or melted. Molten rock that is underground is called magma. When magma reaches the surface of the earth it is called lava. Volcanic eruptions can be explosive or effusive depending on the type of volcano. In general, effusive eruptions are less dangerous. Because less gas is involved in effusive eruptions, explosions are smaller. Eruptions at Mauna Loa are mostly effusive. Its last explosive eruption occurred in 1843.

In the current eruption, lava is flowing out of the northeast side of Mauna Loa. This is good because people are not in immediate danger. The northeast slope of Mauna Loa is not very steep, so lava flows move slower. However, there is a concern that lava could eventually reach and shutdown a key highway in the area. Other possible dangers include impacts to the air from volcanic ash and gasses. Additionally, there is always a chance that lava flows can shift or new flows can be created.

Just a few miles away, the smaller but more active Kilauea volcano is also erupting. Kilauea has been erupting since 1983. In 2018, hundreds of homes were destroyed by its lava flows. Since then, the Kilauea eruption has been limited to the crater of the volcano. Volcanic eruptions are sacred events to many Hawaiians, and dual eruptions haven’t been seen since 1983.

Image credit: ©USGS/ZUMA Press/NewsCom
Question 1
How long has it been since Mauna Loa’s last eruption?

Question 2
Which of the following is a danger created by a volcanic eruption?

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