Our volcano

There are gigantic volcanic mountain ranges, pervading the oceans like veins. Do you know, that this volcanic range is the earth’s longest one? It has a length of 56.000 km. The volcano we are going to visit is located at the East Pacific Rise at 9° 50' N latitude and 104° 17' longitude and is part of the so-called Fire Ring. Have a look at the world map to see where it is.

When plates move apart, the mantle and its magma chambers come close to the surface. During a volcanic eruption molten rock, or magma, gushes out through the crack from beneath the crust. These cracks are called dykes. The diameter of dykes can range from just a few centimeters to two meters.

As soon as magma bursts out onto the surface, it is called lava. Molten rock, once hardened at the surface is called volcanic rock. The most common type of volcanic rock is the firm, black basalt. Lava forming basalt is the most liquid rock. It has the highest temperature and therefore has the highest flow velocity during an eruption. The greatest part of the ocean floor consists out of basalt. Sands and silts cover it most of the time. Sometimes this layer is just a few millimeters thick; sometimes its size can be hundreds of meters.

Bare basalts can be found only at active volcanic sites. Depending on the amount, the velocity and the type of the emerging lava, different types of formations, like lava columns or pillow lava, occur. Pillow lava often features a hyaline (glassy), smooth surface, the black volcanic glass called obsidian.

Left picture, basalt with obsididan on surface. This picture was taken less than a year after the volcanic eruption in 2005/2006. Therefore, no sediment has yet accumulated on it. Right picture shows the extent of lava flow after the eruption with upper fresh basalt and lower part of basalt with little sediment. The lower part was not flooded with lava.