Earthquakes and Volcanoes Section 2. Monday, May 14 Tuesday, May 15. Agenda. Lecture: Earthquakes and Volcanoes Prioritize unit activities Pick 2 options for today (besides lecture). Other announcements. Schedule for today: 8:10-9:05 Assembly 9:10-10:25 Period 2 10:30-11:05 1 st lunch - PowerPoint PPT Presentation
Text of Earthquakes and Volcanoes Section 2
EARTHQUAKES AND VOLCANOESSECTION 2Monday, May 14Tuesday, May 15
Lecture: Earthquakes and Volcanoes Prioritize unit activities Pick 2 options for today (besides lecture)
Schedule for today:8:10-9:05 Assembly9:10-10:25 Period 210:30-11:05 1st lunch11:10-12:35 Period 412:40- 2:00 Period 6
What is an earthquake? Earthquakes occur at plate boundaries Earthquakes are vibrations resulting
from rocks sliding past each other at a fault
(Seismic waves are waves of energy released during in earthquake)
Vocabulary Focus the area along a fault at which the
first motion of an earthquake occurs
Epicenter the point on Earth’s surface directly above an earthquake’s focus
Other websites on EarthquakesTypes of faultshttp://www.iris.edu/gifs/animations/faults.htmRecent map of earthquakes
Shortly after the M7.9 earthquake near Denali National Park, Alaska, Shannon & Wilson engineers were on the road to investigate and document geotechnical damage. The team includes Rohn Abbott, Steve Adamczak, Frank Wuttig, Mark Lockwood, and Bill Perkins.
Tree split in 20- to 30-foot wide rupture zone at Milepost 215.7, Richardson Highway.
Same location as photo 11. Note vehicles for scale.
Ground displacement into lake. Note submerged sand boil and vegetation.
Milepost 77.5, approx. 6 ft vertical, 4 ft horiz. movement across road due to liquefaction of soil below road embankment. Displacements typical of much of road embankments between mileposts 78-75.2
Milepost 78, looking north towards Mentasta Lodge east (right) side of road. Approx. 4 ft vertical, 6 ft horiz. displacement across road SW end of landslide-lateral spread into lake on west side of road
Up to 8ft diameter rocks across Red Rock Canyon Road (1.4 miles east of Richardson Highway at milepost 213.6. Note pickup for scale.
Airport-Typical cracking and lateral displacement in runway surface
Airport-Sand boils at lodge. Differ. settle., lat. movement, foundations tilted inter. floors, opened horiz. cracks between floors-walls. Lodge employee saw 4ft high geysers from boil vents
Airport-Typical sand boil in runway
Airport-Settlement of Hanger relative to floor slab has shortened the height of the door opening and prevents door from closing completely. Residents reported that door closed completely prior to earthquake
Airport-Power pole at lodge that sank approx. 3 feet during. Lodge employee present at time of earthquake reported watching pole sink. Note slack guy wires, which were reportedly taught prior to the earthquake
Earthquakes generate three types of waves:
1. Longitudinal waves travel by compressing and stretching crust, also
called primary waves (P waves)
2. Transverse waves travel in an up and downward movement,
also called secondary waves (S waves)(Both P waves and S waves spread out from the focus in all
directions through the earth.)
3. Surface waves (Surface waves move only on Earth’s surface.)
seismic waves that can move only through solids, move in a rolling circular motion
surface waves D:\Ch21\80078.html
Seismologists detect and measure earthquakes.
Seismology the study of earthquakes including their origin, propagation, energy, and prediction• Seismologists use sensitive equipment called
seismographs to record data about earthquakes.
• Seismograph D:\Ch21\80079.html
How to calculate the epicenter of an earthquake?
• Because P waves travel faster, the difference between the arrival of P waves and the arrival of S waves allows scientists to calculate how far away the focus is.
• Three seismograph stations are necessary to locate the epicenter of an earthquake.
How to calculate the magnitude of an earthquake? Richter scale a scale that expresses
the magnitude of an earthquake
Magnitude of earthquake D:\Ch21\80105.html
Why does the Pacific Northwest have earthquakes? We are located at a convergent
continental boundary, where two tectonic plates are colliding.
This boundary is called the Cascadia Subduction Zone. It lies offshore and runs from British Columbia to northern California.
The two plates are converging at a rate of about M 3-4 cm/year (1-2 inches/year), and the northeast-moving Juan de Fuca Plate is pushing into North America, causing stress to accumulate.
Earthquakes are caused by the abrupt release of this slowly accumulated stress.
Hazards in the PNW/diagram of faults and volcanoes
What is a volcano?A volcano is any opening in Earth’s crust
through which magma has reached Earth’s surface.
Vent an opening at the surface of Earth through which volcanic material passes.
So we call it magma or lava?Magma that reaches Earth’s surface is called
Types of Volcanoes
have mild eruptions.
forms a gently sloping mountain.
Shield volcanoes are some of the largest volcanoes.
3 types of volcanoes D:\Ch21\80116.html
Composite volcanoes are made up of alternating layers of ash, cinders, and lava.
The lave is thicker than that of shield volcanoes.
Gases are trapped in the magma, causing eruptions that alternate between flows and explosive activity that produces cinders and ash.
Composite volcanoes are typically tall with steep sides.
Cinder cones• are the most abundant volcano.
•Cinder cones are the smallest and most common volcanoes.
•Large amounts of gas are trapped in the magma, and violent eruptions of hot ash and lava occur.
•Cinder cones tend to be active for only a short time and then become dormant.
Where do volcanoes occur? (there are 3 places)
1) Most volcanoes occur at convergent plate boundaries.
• 75% of the active volcanoes on Earth are located in an area known as the Ring of Fire.
• The Ring of Fire is located along the edges of the Pacific ocean, where oceanic tectonic plates are colliding with continental plates.
Other places to find volcanoes2) Underwater volcanoes occur at
divergent plate boundaries.
• As plates move apart at divergent boundaries, magma rises to fill the gap.
• This magma creates the volcanic mountains that form ocean ridges.
• Iceland is a volcanic island on the Mid-Atlantic ridge that is growing outward in opposite directions.
One more common spot
3) Volcanoes occur at hot spots.• Some volcanoes occur in the middle of plates. Hot spots D:\Ch21\80124.html
Mantle plumes are mushroom shaped trails of hot rock that rise from deep inside the mantle, melt as they rise, and erupt from volcanoes at hot spots at the surface.
• The plumes remain in the same place as the tectonic plate moves, creating a trail of volcanoes.
• The Hawaiian Islands are an example of this type of volcanic activity.
All students will complete the lecture notes for each section in their handbook/journal.
All students must define any vocabulary from the GLE evaluation sheet that is not familiar to them.
All students will end up with the equivalent of 10 activities (4 sections of notes + 6 activities).
How to pick your activities?
Score of 4 = Lecture notes Score of 3 = Lecture notes + one more
option from section Score of 2 = Lecture notes, review of
content + one more option from list Score of 1 = Lecture notes, review of
content, lab, + one additional activity
Today in Science
On May 14, 1850, the first U.S. patent for this machine was issued to Joel Houghton of Ogden, NY, for an "Improvement in Machines for Washing Table Furniture”
What was this machine that most people now have in their kitchens?
Today in Science
This female scientist, Williamina Paton Stevens Fleming, was born on 15 May 1857.She was a Scottish-born American astronomer who pioneered in the classification of stellar spectra and the first to discover these types of stars. Prof. Edward Pickering, director of the Harvard Observatory first employed Fleming as a maid, but in 1881 hired her to do clerical work and some mathematical calculations at the Observatory. She further proved capable of doing science. After devising her system of classifying stars by their spectra, she cataloged over 10,000 stars within the next nine years. Her duties were expanded and she was put in charge of dozens of young women hired to do mathematical computations (as now done by computers). The type of star she discovered will be the fate of our sun one day. What type of star did she discover?
The “white dwarf”
Today in Science
In 1935, at the Franklin Institute, Philadelphia, this scientist was awarded the Benjamin Franklin Medal for his outstanding fundamental contributions to theoretical physics, especially his relativity theory. Who was this famous scientist?