Glaciers and Earthquakes By: Michael Humann

Glaciers: An overview Introduction to Glaciers Types of Glaciers Glacier Bay, Alaska Interesting Facts

Introduction to Glaciers So what is a glacier? Glaciers are made up of fallen snow that accumulates over years and years of snow fall in the same place. After many years the snow begins to compress and forms ice. What is unique about glaciers is that they move. Why do they move? Once they reach around 20m thick, the ice becomes so heavy that they begin to move with the aid of gravity. The ice may fan across plains, or travel down mountain valleys.

The bottom of the glacier moves much slower than the top due to the friction between the ground and the glacier. This is called the zone of plastic flow. Glaciers can both retreat and advance. The movement of glacier is something that happens over a long period of time, but in some extreme and rare cases it can move very rapidly as much as a few meters per day.

Types of glaciers Tidewater glaciers- are glaciers that extend far enough to reach the sea. These glaciers are responsible for calving small ice bergs into the sea. Where the ice meets the sea it creates a moraine shoal which is a deep mound of debris in front of the place of terminus. The terminus is the term for where the glacier meets the sea.

Valley Glaciers- starts high in the mountains and flows down the mountain valley. Some examples of valley glaciers are the Muldrow and Kahiltna in Denali National Park. This is an example of a Valley Glacier

Ice Sheet- a very thick glacier that covers a large area Ice Sheet- a very thick glacier that covers a large area. They must be bigger than 50 thousand sq. kilometers in order to be classified as an ice sheet. Antarctica and Greenland are two places where ice sheets exist today Piedmont Glacier- when a glacier or an ice stream flows from the mountains into a plane where the glacier then spreads out

Glacier Bay, Alaska In 1794 Glacier Bay was founded by Captain George Vancouver It is located in Southeast Alaska and is one of the most active areas for glaciers calving into the sea. It is a popular tourist attraction.

It has 16 tidewater glaciers Glacier Bay has both tidewater glaciers and some other types of glaciers It has 16 tidewater glaciers Some of the glaciers include the Carroll and Cushing Glaciers, Riggs and McBride Glaciers, Muir and Johns Hopkins This is a satellite image of the Carroll and Cushing Glaciers

Interesting Facts: Glaciers store about 75% of the world’s freshwater. Glacier ice crystals can grow to be as large as baseballs. North America’s largest glacier is the Berling Glacier in Alaska, measuring 204 kilometers long. Antarctic ice is over 4,200 meters thick in some areas Almost 90% of an iceberg is below water, only about 10% shows above water. If all land ice melted, sea level would rise approximately 70 meters worldwide. In Washington state alone, glaciers provide 470 billion gallons of water each summer.

Satellite image of Glacier Bay

Earthquakes Earthquakes: An Introduction What causes Earthquakes? The 3 Fault Zones History of Earthquakes

Introduction to Quakes Ever since the beginning of the Earth, tech-tonic plates have moved to shape the Earth into the shape it is in today. This still occurs today. Plates shift gradually over time, but sometimes they get stuck and after some time the plates break loose which results in a violent shift in the landing and shaking and trembling. This is an earthquake.

Earthquakes are some of me deadliest forms of natural disasters and over time have been responsible for the deaths of thousands. A picture from the 1906 earthquake in San Franscico

Why do Earthquakes Happen? The outer layer of the earth is about 70km thick and is made up of roughly 12 irregularly shaped plates. Quakes happen where these plates meet and overlap each other. There are 3 different types of fault zones. They are spreading zones, subduction zones and transform faults.

The place where the quake originates is called the epicenter. Earthquakes are created by the crust breaking or being dislodged. This is when the most powerful quakes happen. Vibrations are then sent through the earth, these are called seismic waves. The waves are sent out in a ring shape. The place where the quake originates is called the epicenter.

The 3 Fault Zones Spreading Zones- are zones where two plates are pushed up by molten lava and new material is formed there. The mid-Atlantic ridge is a very good example. Transform Faults- is a place where two plates slide past each other, the San Andreas fault is a transform fault.

Subduction Zones- this is a zone or area where one plates rides on top of the other or subducts and it melts in the mantle. The San Andreas fault which is a transform fault.

History of Earthquakes A earthquake is measured by a tool called a seismograph. The scale which quakes are measured on is called the Richter Scale. The biggest earthquake ever recorded was in Chile in 1960 and was a 9.5.

The deadliest quake was last year Dec. 26,2004 off the coast of Sumatra. Most of the fatalities were due to the tsunami caused by the quake and roughly 280,000 people died. The largest quake in the U.S. was in Price William Sound, Alaska in 1964.

Review Questions What are the names of the 3 types of fault zones? Subduction, transform, and spreading. How many tidewater glaciers are in Glacier Bay, Alaska? 16 What is the area between the bottom of the glacier and the ground called? Zone of plastic flow Roughly how thick is the outer crust of the earth, and how many plates does the earth contain? 70km and 12 How much of the earth’s freshwater do glaciers store? 75%

Sources http://libraryphoto.er.usgs.gov/earth1.htm http://pubs.usgs.gov/gip/earthq1/ http://www.nps.gov/glba/ http://nsidc.org/glaciers/