earthscience

The Four Earth Sciences

Many different sciences are used to learn about the earth, however, the four basic areas of Earth science study are: geology, meteorology, oceanography and astronomy. A brief explanation of these sciences is provided below.

Geology: Science of the Earth

Geology is the primary Earth science. The word means "study of the Earth". Geology deals with the composition of Earth materials, Earth structures, and Earth processes. It is also concerned with the organisms of the planet and how the planet has changed over time. Geologists search for fuels and minerals, study natural hazards, and work to protect Earth's environment.

Meteorology: Science of the Atmosphere

Meteorology is the study of the atmosphere and how processes in the atmosphere determine Earth's weather and climate. Meteorology is a very practical science because everyone is concerned about the weather. How climate changes over time in response to the actions of people is a topic of urgent worldwide concern. The study of meteorology is of critical concern for protecting Earth's environment.

Oceanography: Science of the Oceans

Oceanography is the study of Earth's oceans - their composition, movement, organisms and processes. The oceans cover most of our planet and are important resources for food and other commodities. They are increasingly being used as an energy source. The oceans also have a major influence on the weather and changes in the oceans can drive or moderate climate change. Oceanographers work to develop the ocean as a resource and protect it from human impact. The goal is to utilize the oceans while minimizing the effects of our actions.

Astronomy: Science of the Universe

Astronomy is the study of the universe. Here are some examples of why studying space beyond Earth is important: the moon drives the ocean's tidal system, asteroid impacts have repeatedly devastated Earth's inhabitants and energy from the sun drives our weather and climates. A knowledge of astronomy is essential to understanding the Earth. Astronomers can also use a knowledge of Earth materials, processes and history to understand other planets - even those outside of our own solar system.

Northridge Earthquake

Northridge Earthquake

At 4:30 am, on January 17, 1994, residents of the greater Los Angeles area were rudely awakened by the strong shaking of the Northridge earthquake. This was the first earthquake to strike directly under an urban area of the United States since the 1933 Long Beach earthquake.

The earthquake occurred on a blind thrust fault, and produced the strongest ground motions ever instrumentally recorded in an urban setting in North America. Damage was wide-spread, sections of major freeways collapsed, parking structures and office buildings collapsed, and numerous apartment buildings suffered irreparable damage. Damage to wood-frame apartment houses was very widespread in the San Fernando Valley and Santa Monica areas, especially to structures with "soft" first floor or lower-level parking garages. The high accelerations, both vertical and horizontal, lifted structures off of their foundations and/or shifted walls laterally

Japn's earthquake tsunami

causes of japan's tsunami

That earthquake happened on the ocean floor more than 200 miles from Tokyo. Arizona State University professor of earthquake geology Ramon Arrowsmith says sections of the ever-moving earth's crust, known as plates, began to lift after colliding. 

That earthquake happened on the ocean floor more than 200 miles from Tokyo. Arizona State University professor of earthquake geology Ramon Arrowsmith says sections of the ever-moving earth's crust, known as plates, began to lift after colliding. 

Arrowsmith says that energy gave birth to huge waves on the ocean's surface. Those waves became tsunamis when the crashed ashore in Japan.

While Friday’s horrific destruction caused by the quake and tsunami may seem a once-in-a lifetime disaster to us, Professor Arrowsmith says it's nature's way and has happened often in the past and will happen again in the future.

casualties
 
Tokyo, Japan, March 15, 2011 /WNCNews/ – The death toll from the earthquake that followed by  tsunami which flattened most of the northeastern coast of Japan, to reach at least 2,400 people.

Japan National Police Agency, on Tuesday (March 15, 2011) said, 2414 people are confirmed dead and 3118 missing, while 1885 were injured due to earthquake and tsunami that struck Japan on Friday (March 11, 2011) ago. Number of victims yesterday officially consisted of 1647 people.

On Sunday (March 13, 2011), police chief of Miyagi, one of the prefectures hardest hit disaster, said the number of death toll is estimated at more than 10,000 in its own territory.

In the midst of a mass rescue efforts, there has been data updates showing severe loss along the east coast of Honshu island, where the tsunami waves destroyed or damaged more than 55,380 homes and other buildings.

More than 3,000 houses were flooded by the sea water of tsunami, while about 130 other houses on fire, police said. They added that there are at least 68 landslides in those areas.

Hazardous earthquakes in california

The presence of the San Andreas fault was brought dramatically to world attention on April 18, 1906, when sudden displacement along the fault produced the great San Francisco earthquake and fire. This earthquake, however, was but one of many that have resulted from episodic displacement along the fault throughout its life of about 15-20 million years.

What Is It?

Scientists have learned that the Earth's crust is fractured into a series of "plates" that have been moving very slowly over the Earth's surface for millions of years. Two of these moving plates meet in western California; the boundary between them is the San Andreas fault. The Pacific Plate (on the west) moves northwestward relative to the North American Plate (on the east), causing earthquakes along the fault. The San Andreas is the "master" fault of an intricate fault network that cuts through rocks of the California coastal region. The entire San Andreas fault system is more than 800 miles long and extends to depths of at least 10 miles within the Earth. In detail, the fault is a complex zone of crushed and broken rock from a few hundred feet to a mile wide. Many smaller faults branch from and join the San Andreas fault zone. Almost any road cut in the zone shows a myriad of small fractures, fault gouge (pulverized rock), and a few solid pieces of rock.

Where Is It?

The San Andreas fault forms a continuous narrow break in the Earth's crust that extends from northern California southward to Cajon Pass near San Bernardino. Southeastward from Cajon Pass several branching faults, including the San Jacinto and Banning faults, share the movement of the crustal plates. In this stretch of the fault zone, the name "San Andreas" generally is applied to the northeastern most branch.

seismic waves

seismic wave, vibration generated by an earthquake explosion, or similar energetic source and propagated within the Earth or along its surface. Earthquakes generate four principal types of elastic waves; two, known as bodywaves, travel within the Earth, whereas the other two, called surfacewaves, travel along its surface. seismographs record the amplitude and frequency of seismic waves and yield information about the Earth and its subsurface structure. Artificially generated seismic waves recorded during seismicsurveys are used to collect data in oil and gas prospecting and engineering.

strata and shield volcanoes

Strata volcano

 Stratovolcanoes have steep sides with cones that stick out like huge bumps. They are built up when eruptions of viscous lava, tephra, and pyroclastic flows happen. It takes thousands of years for the pressure to build up enough in stratovolcanoes to cause an eruption. More than one kind of magma builds up in stratovolcanoes. They are basalt, andesite, dacite, and rhyolite magma. All of those magmas cause explosive eruptions except basalt magma. There are a lot of different vents around stratovolcanoes. Some of the vents are cinder cones and domes low on the sides of the volcano. Sometimes stratovolcanoes are called composite cones.


shield volcano

Shield volcanoes are large volcanoes that are built almost entirely of fluid lava flows. It has broad sloping sides and is usually surrounded by gently sloping hills in a circular or fan shaped pattern, that looks like a warrior's shield.
The volcano is produced by the action of the gas (steam or water vapor) with heat from the earth's core. This action melts rock turning it into magma. The pressure from the heat of the gas pushes the magma upwards till it explodes. Molten magma shoots upward from deep below the ocean floor and breaks through the drifting plates to form shield volcanoes. Lava flows gently and continuously out of the central volcanic vent or group of vents. This lava is very runny, and can't be piled up into steep mounds. It gradually accumulates and cools around the volcano. The eruptions are characterized by low explosivity lava-fountaining that forms cinder cones and spatter cones at the vent. The volcanoes are built up slowly by the accretion of thousands of highly fluid lava flows called basalt lava. The lava spread widely over great distances, then cools as thin gently dipping sheets. Lavas also erupt from vents along fractures (rift zones) that form on the flanks of the cone. Some of the largest volcanoes in the world are Shield volcanoes.

Batholith

Batholith

 If you come across an outcrop (exposure) of coarse-grained igneous rock, chances are you are standing on a pluton or batholith that crystallized several km below the Earth's surface. It may represent the magma chamber of an extinct volcano or a magma body that never produced any eruptions.

Batholiths indicate a long period of repeated igneous intrusions over a large area, such as might be expected along a subduction zone.

The Sierra Nevada Batholith

The Sierra Nevada Batholith of eastern California forms the largest mountain range in the continental U.S. Although the prospect of walking across huge areas of one type of rock--granite--might seem dull, in fact the Sierras offer spectacular scenery and lots of interesting details about what went on in the magma chambers of a suite of subduction zone volcanoes that were active from roughly 150 to 80 million years ago. Intrusive rocks offer many clues as to the inner workings of the Earth!