Wk4_Freeman_J_Volcanoes

image credit:wikipedia 

 This week for our travel Journal I decided to visit Mt. Saint Helens right here in my own backyard of the PNW. Mt. Saint Helens is famous for numerous reasons, the one pertaining most to our class focus is the volcanic eruption of 1980. Mt. Saint Helens is a composite volcano or stratovolcano. A composite volcano is the picturesque typical volcano image that comes to most people’s mind when you mention a volcano. Nearly symmetrical cone structure on the outside, but inside they consist of alternating layers of explosive ash and cinder interbedded with lava flows. This is how the volcano is formed, through countless eruptions over hundreds of thousands of years. The eruptions build upon the composite materials and volcano until layer over layer is formed to create the spectacle that we see today.

 Stratovolcanoes are the most potentially dangerous when considering volcanic eruption activity. Mt. Saint Helens is still considered an active volcano, its most recent “small” eruption taking place in 2008. Mt. Saint Helens eruptions are explosive, not effusive (meaning flowing or pouring out). The nature of a volcano’s eruption directly correlates to its magma composition. Volcanoes like Mt. Saint Helens, (composite) reflect the viscous nature of their magma. The magma is composed of felsic minerals, containing high silica amounts. This creates a very viscous magma that contain concentrated gasses and erupt at the lowest temperature thresholds. You can still see the consequences of previous eruptions on Mt. Saint Helen’s summit elevation and appearance. While the volcano has lost its picturesque symmetrical cone, it is still a majestic sight to behold that demands respect.

 The 1980 eruption of Mt. Saint Helens was the most devastating and economically damaging eruption in the entire history of the United States. Given it’s position just 96 miles from Seattle, and only 50 miles from Portland, the implication of another massive eruption is grave. Some of volcanic hazards to consider with Mt. Saint Helens include massive volcanic ash pollution and downfall over several days, eruption of lava flows, and pyroclastic flows (lava flows consisting of hot gases infused with incandescent ash and larger lava fragments). Geologists tell us that while it is still an active volcano, there is no immediate threat of volcanic eruption activity.