Post date: Jun 24, 2016 4:22:25 PM
eLink to the JPL lesson: http://www.jpl.nasa.gov/edu/teach/activity/lava-layering-making-and-mapping-a-volcano/
Here are some real-world examples that complement these lessons, along with my own scientific commentary:
Kilauea, Hawaii: This is exactly what you see in the lesson. These eruptions have all happened in your lifetimes and many of them in your students’ lifetimes. Which eruptions came from the vent named “Pu’u O’o?” Pay particular attention to the tiny yellow strip of the 1997 eruption that happened along a fissure. Did any other eruptions look like they came from that fissure, or was it a ‘one time deal?” “What causes the lava flows to ‘move around’ even though when they come out of the same vent (You can answer this using your play dough models — it involves tiny variations in the thickness of the solidified lava in some places that re-route future lava flows). What causes the VENT to move around (the plumbing can get temporarily or permanently clogged up, causing the lava to break through in other areas). Read more, including a similar map for all of Hawaii.
Mt. Ranier, Washington: Slightly more complex because these old lava flows (up to 500,000 years old, or “500 ka”) have been carved away by erosion on the steep mountain sides. Also, the very top of the mountain is covered by a glacier! Read more...
Mammoth Mountain, California: Mammoth’s lava flows tell a much more complicated history than Kilauea. The following layers on this map are lava flows: Qv1, Qv2, Qv3, MMdr, and Ri. There are also deposits from small steam explosions (Qpe) that are pretty recent, and super explosive ash falls (Bt, Rr) that are much older (760,000 for the Bishop Tuff, BT). The abbreviation ‘ka’ means thousands of years ago. Notice that the top of Mammoth mountain (the dark red MMdr) is NOT the youngest layer. Mapping out the age of lava flows in this area tells us that the vent moves around. The small steam explosions (Qpe) and more recent eruptions (Ri) are not coming out of the top of Mammoth Mountain. Does this mean that Mammoth is extinct and will never erupt? Or does it just mean that the next eruption will be much bigger than Mammoth? We don’t yet have enough observations to answer these questions.
Advanced observers: Also notice that the recent eruptions (Qpe and Ri) line up in a line that runs roughly north-south. What causes this linear pattern? Well, every time we see a pattern [CCC-1] of landform structures [CCC-6] in geology, we know that there must something that causes [CCC-2] this “function." The clue is the black lines labeled ‘fault’. All the magma seems to be squeezing into an existing fault.
Teacher background: If you are interested, check out my 5 part video series on monitoring volcano hazards. It’s lengthy, but seems to get a lot of hits on YouTube with comments saying people found it interesting and useful:
Professor d'Alessio's Volcano Monitoring YouTube Video Playlist