Mauna Loa, what we know about the volcano erupting after 40 years of inactivity

Mauna Loa

The eruption of Mauna Loa, which began at 11.30 yesterday morning (Italian time), should not pose a danger to the nearby inhabited centers of the island, according to the latest bulletins of the United States Geological Institute (Usgs). The latest dates back to four o'clock this night (Italian time), and says that the eruption was concentrated in the northeastern Rift Zone, and at the moment there are no threatened populated areas. The next bulletin is expected in a few hours, when the sun will rise again on the island.

What's happening

The eruption that began yesterday morning, Monday 28 November around 11.30 (Sunday evening at 23.30 local time in the Hawaiian Islands), has so far affected three fissures. Initially the lava began to flow out of the caldera, then also from the flanks and at the moment the eruption is particularly affecting the north-eastern area of ​​the volcano. The direction is the opposite from the neighboring city Kona; therefore, at the moment there has been no evacuation order. Some roads near the volcano have been closed and experts are monitoring atmospheric conditions to prevent the concentration of dust and gas from becoming dangerous for citizens.

According to reports from the Usgs, the highest lava fountains are between 30 and 60 meters, but most of them are a few meters high. The flows from the top two fissures have moved down and are expected not to reactivate, while the third is currently feeding lava flows moving eastward parallel to the NE Rift Zone. While parameters monitored by experts indicate that the eruption will remain in the Northeast Rift, volcanic gas, fine ash and Pele's hair (droplets of magma cooled, vitrified and shaped by winds into a hair-like shape) may be carried downwind.

The largest volcano in the world

Mauna Loa is located on the island of Hawaii , the largest and youngest of the archipelago at the southeast tip of Hawaii, and occupies more than half of the island's surface. Measured from sea level, the summit is 4,169 meters high, but its sides extend to the ocean floor for about 5,000 meters, so that the Pacific plate is bent downward by its weight. Its surface area is estimated to be around 5,000 square kilometers, making it the active volcano with the largest volume in the world. It is a shield volcano and is formed by a summit caldera and two rifts: the Northeast Rift Zone and the Southwest Rift Zone. These are lateral fractures typical of shield volcanoes, which form at structural weaknesses and allow magma from a reservoir below the summit to move up the flanks and rise vertically, fueling an eruption. In addition to these, on the slopes of the volcano there are also "radial vents", oriented radially with respect to the caldera and outside of it and the rift zones. One of these vents erupted in 1859, but it has only happened three times in the last 200 years.

The latest episodes

Mauna Loa has erupted 33 times since 1843 . The last eruption dates back to 1984 and lasted about three weeks (from 24 March to 15 April). These forty years have been the longest period of quiet in the history of the volcano. Recently, however, there has been an increase in seismic activity and earthquake rates on the island.