Download Cascades?

Map of US Volcanoes and Current Activity Alerts: https://volcanoes.usgs.gov/index.html
1. Describe the patterns you see including the alert levels.
http://www.pnsn.org/volcanoes
Seismicity
The PNSN is responsible for the routine seismic monitoring of the Cascade range volcanoes in Oregon
and Washington and coordinates very closely with the Cascade Volcano Observatory (CVO) of the US
Geological Survey's Volcano Hazards Program who monitor many other parameters and have the
mandate to study and evaluate all volcanic hazards.
The above plot is updated frequently to show the distribution of earthquakes located at or very near the
major volcanoes. Under many of the volcanoes' special pages there are "seismicity" tabs giving updated
maps, time-depth plots and seismiscity rate plots to help understand the seismic activity at each.
Volcano Summary
There is a weekly update provided by the CVO for Cascade Volcano status.
Cascadia is home to numerous active volcanoes that form as a part of the subduction process. Volcanic
eruptions in the Cascades are infrequent, but may be violent. Here is a graphic indicating the eruptive
history of many volcanic centers based on the geologic record.
Eruptive episodes are likely to be accompanied by copious seismicity as magma works its way to the
surface. Earthquakes, even "swarms" of earthquakes at volcanoes are not necessarily a sign of an
impending eruption, but together with other observations (deformation, gas emission, temperature
changes) they provide one important and early clue when eruptions may be approaching. Volcano
seismologists track not only earthquakes, but also various kinds of seismic signals with special
characteristics that suggest magma movement.
A special challenge at Cascade volcanoes is seismic activity associated with glacier movement, icefalls,
and rockfalls—these are the most common signals we see! Distinguishing between all the different types
of seismic sources can be difficult: a job for a specialist.
These pages provide an ongoing overview of earthquake activity at the monitored volcanoes in
Washington and Oregon. Simply the number of located earthquakes at or near a volcano is not
necessarily indicative of impending volcanic activity. Besides number and size there are waveform
characteristics, changes in these characteristics, event depth, and changes in exact locations that go into
the interpretation of seismicity patterns. These interpretations are combined with other available
geophysical monitoring parameters and a good understanding of the geologic history of a volcano to
arrive at forecasts for future volcanic activity. The PNSN along with the CVO uses both automatic and
manual reviews of our data to keep a close eye on our volcanoes. We are confident that we will recognize
and be able to interpret the precursory geophyscal events that inevitably occur before significant volcanic
eruptions.
1. Which volcanoes erupted during the past 200 years?
2. What does the diagram suggest about the likelihood of future volcanic activity in the
Cascades?
3. Based on the eruptive history represented by the timeline, which volcano do you think
is most likely to erupt next? Explain your answer.
Yellowstone
This presentation focuses on the eruption history of the Yellowstone region. First, you will view a seven
minute video about volcanoes and hydrothermal features. To watch it, click anywhere on this slide.
Then, you’ll examine a few maps to see where Yellowstone National Park is and its significant features—
geological as well as practical ones like roads and villages. Finally, you’ll learn more about the history of
eruptions in Yellowstone while your teammates learn more about earthquakes and hydrothermal
systems.
The link to the video takes you to the American Museum of Natural History’s Science Bulletin:
“Monitoring the Fire Below”.
http://www.amnh.org/explore/science-bulletins/(watch)/earth/documentaries/yellowstonemonitoring-the-fire-below
Yellowstone lies partially in three states -- Montana, Idaho and Wyoming.
Much of Yellowstone is a large crater (a “caldera”) that is surrounded by cliffs. The cliffs are topped by
lava flows. This picture was taken from the top of a lava flow. The green bluffs below the mountains
are the rim of the caldera. In the foreground are two lava flows.
Yellowstone is one of the largest and most active calderas in the world. Eruptions in Yellowstone started
about 2.3 million years ago. But, they follow a string of eruptions through the region that has left a path
of calderas. Click on this slide and then on “Interactive: A Hotspot Trail” on the webpage to explore an
animation of volcanism moving across the region over time. The center of volcanism has moved
because the North American plate is moving over a “hotspot” in the mantle that produces magma by
melting rocks in the crust.
Between the caldera-forming events (three in Yellowstone), other lava eruptions and hydrothermal
eruptions occurred. The topography of the older craters is quite flat because of millions of years of
erosion and burial by other volcanic events such as the Snake River Plain flood basalts.
Don’t worry, don’t panic about this figure…. It is complicated but it shows the science behind the
animation you explored in the previous slide. It shows the ages of volcanic rocks in the region to the
west of Yellowstone. The big yellow Y is where the Yellowstone hot spot currently is.
This figure compiles the work of many geologists and is published in a scientific research journal. It’s
this kind of article, and the research that goes into it, that allowed the American Museum of Natural
History to build the animation you explored on the previous slide.
There have been about 80 lava flows since the most recent caldera formed 640,000 years ago. This map
uses color to show different ages of the rocks, both inside and outside the caldera. It also shows
earthquake epicenters and faults.
Clicking on the map links to The American Museum of Natural History’s Science Bulletin. Select the
“Different magma - Different volcano” interactive link on this page to investigate the relationship
between the different kinds of lava and volcanoes.
The collapse of calderas is cataclysmic. Rocks and lava explode upward and outward as the caldera
collapses, and the debris covers huge regions. This map shows how far volcanic ash went during the
2,100,000 and 630,000 year-old eruptions that led to calderas in Yellowstone.
Your team will be using Google Earth to compare where the interesting features in the park are. You do
not have any specific data within Google Earth with the exception of the caldera rim. However, you can
examine other maps in this PowerPoint presentation to determine how the eruption history might
influence places you suggest (or do not suggest) for research station placement and mark according in
Google Earth using the “polygon” feature.
You will be able to turn layers on and off by checking the data sources of interest in the “Places” bar in
the left of Google Earth.
For help with Google Earth, refer to this Guide.
http://serc.carleton.edu/sp/library/google_earth/UserGuide.html