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Geophysics
The study of Earth using the combination of Geology and Physics, it lets us understand what is going on under the Earth's surface. Find questions on different types of seismic activities such as earthquakes and volcano eruptions here.
1,480 Questions
Where are the earthquakes located on the map?
The largest earthquake recorded to date was a magnitude 9.5 that occurred in Chile on Sunday, May 22, 1960.
Approximately 1,655 people were killed, 3,000 injured, 2 million homeless, and $550 million damage in southern Chile. The resulting tsunami caused 61 deaths, $75 million damage in Hawaii; 138 deaths and $50 million damage in Japan; 32 dead and missing in the Philippines; and $500,000 damage to the west coast of the United States.
What are the seismic waves of the Earth's crust?
Rock under stress breaks at the focus, releasing energy and vibrations called seismic waves, which travel away from the focus, through Earth's interior, and across the surface.
The three types of seismic waves are:
Primary waves: The first to arrive at seismographs
Secondary waves: The second to arrive at seismographs
Surface waves: The last and most severe to arrive at seismographs
Who developed the theory of continental drift?
That the continents move relative to each other, slowly drifting towards each other and forming together into super-continents.
He thought that all the continents were one supercontinent called Pangaea.
When was continental drift first believed?
Alfred Wegener publically promoted the theory as early as 1912. Although he was convinced it was correct, it did not gain wide acceptance until the 1960s. Today we have measurements of the rates and directions of drift of the various place established with highly accurate GPS observations.
The energy of an earthquake called seismic waves originates from a point called the?
the energy of an earthquake, called seismic waves,originates from a point called the ? epicenter
What is the most common type of rock on earth's surface?
Sedimentary Rocks. 75% of rocks exposed to the surface are sedimentary.
How did continental drift happen?
Continental Drift happened, when the tectonic plates in the earth shifted, and pushed the lithosphere up, causing our continents to split.
What are most plate boundarise on?
plate boundry has four different parts. # conservative boundary. # constructive boundary. # destructive boundary. # collision boundary.
What evidence did wegner have for continental drift theory?
Actually there is a lot of evidence that supported his evidence the big one was fossils of animals on distant continents and plants for example Glossopteris was one the strange reasons that Alfred was more than ever to prove his point.
Edit:
Alfred Wegener proposed that, using 19th century longitude determinations, Greenland had moved 1 mile away from Europe. However, this conclusion ended up being false due to false calculations. Still, Wegener discovered that every year San Diego moved 6 feet closer to Shanghai while Washington D.C. and Paris got 15 feet closer. In addition, Alfred Wegener discovered that related species, too small to swim across the ocean, were found on different continental plates, as well as similar fossils.
Alfred Wegener's theory was rejected at first, however, because he was unable to explain the reason why the plates moved. Later, Arthur Holmes published his theory of thermal convection being the the thing that drove the plates apart. He also noted that the continents didn't "move" but were "carried" by larger pieces of the Earth's crust. Discoveries of the Mid-Ocean Ridge in addition to Harry Hess's work adds onto this theory of Wegener's.
As this theory is the most complete theory concerning global dynamics, the roots of such lie in the curiosity and work of Alfred Wegener.
What is sandblasting of rock by wind-blown particles?
Sandblasting of rock by wind-blown particles is referred to as abrasion. It is the process of scraping or wearing away of rock particles.
What instrument measures seismic activity?
By the way, the term geophone derives from the Greek word "geo" meaning "earth" and "phone" meaning "sound".
A geophone is a device which converts ground movement (displacement) into voltage, which may be recorded at a recording station. The deviation of this measured voltage from the base line is called the seismic response and is analyzed for structure of the earth.
Geophones have historically been passive analog devices and typically comprise a spring-mounted magnetic mass moving within a wire coil to generate an electrical signal. Recent designs have been based on Microelectromechanical systems technology which generates an electrical response to ground motion through an active feedback circuit to maintain the position of a small piece of silicon.
The response of a coil/magnet geophone is proportional to ground velocity, while microelectromechanical systems devices usually respond proportional to acceleration. Microelectromechanical systems have a much higher noise level (50 dB velocity higher) than geophones and can only be used in strong motion or active seismic applications.
The frequency response of a geophone is that of a harmonic oscillator, fully determined by corner frequency (typically around 10 Hz) and damping (typically 0.707). Since the corner frequency is proportional to the inverse root of the moving mass, geophones with low corner frequencies (< 1 Hz) become impractical. It is possible to lower the corner frequency electronically, at the price of higher noise and cost.
Although waves passing through the earth have a three-dimensional nature, geophones are normally constrained to respond to single dimension - usually the vertical. However, some applications require the full wave to be used and three-component or 3-C geophones are used. In analog devices, three moving coil elements are mounted in an orthogonal arrangement within a single case.
The majority of geophones are used in reflection seismology to record the energy waves reflected by the subsurface geology. In this case the primary interest is in the vertical motion of the Earth's surface. However, not all the waves are upwards travelling. A strong, horizontally transmitted wave known as ground-roll also generates vertical motion that can obliterate the weaker vertical signals. By using large areal arrays tuned to the wavelength of the ground-roll the dominant noise signals can be attenuated and the weaker data signals reinforced.
Analog geophones are very sensitive devices which can respond to very distant tremors. These small signals can be drowned by larger signals from local sources. It is possible though to recover the small signals caused by large but distant events by correlating signals from several geophones deployed in an array. Signals which are registered only at one or few geophones can be attributed to ll, local events and thus discarded. It can be assumed that small signals that register uniformly at all geophones in an array can be attributed to a distant and therefore significant event.
The sensitivity of passive geophones is typically 30 Volts/(meter/second), so they are in general not a replacement for broadband seismometers.
Conversely, some applications of geophones are interested only in very local events. A notable example is in the application of Remote Ground Sensors (RGS) incorporated in Unattended Ground Sensor (UGS) Systems. In such an application there is an area of interest which when penetrated a system operator is to be informed, perhaps by an alert which could be accompanied by supporting photographic data.
seismograph
What should you do if a hurricane is approaching where you live?
Make sure you follow the evacuation and preparation advice from officials if you are located in a coastal region. Never open doors or windows letting in the wind during a hurricane.
Before the threat of any hurricane it's a good idea to have basic supplies together such as food, water, am radio, etc. Anything you will need for survival in case of power outages.
To protect your home you should reinforce door and window locks, the garage door, and any other vulnerable weak points around the home. Clean up and put away items that could blow away outside.
Windows are the most vulnerable so protect the glass from breaking with hurricane shutters, screens, or boards. Security window film won't keep the glass from breaking but it will help keep the glass from shattering in small glass shards or even retain the glass in the frame.
If you can keep the glass from breaking and stop the wind from blowing open a door, then you should be a lot safer if a hurricane hits your home. Once the wind enters your home it might blow off your roof and cause server damage.
What is the function of each of the layer of the earth?
Basically as follows-
Crust- The "shell" and barrier that keeps our earth from being a lava planet.
Mantle- Soft "Clay-like" rock that is hot and convection currents here cause the movements of the plates in the lithosphere
Core- Place where rock is liquit and melted in the outer core, inner core is solid nickel and iron, makes up Earth's magnetic field.
Why are the Himalayan region and ganga-brahmaputra valley most prone to earthquakes?
shiwalik is made up of unconsolidated sediments and is the lowermost part of the himalayas.it is found near river valleys which erodes the soil and hence prone to landslides .it is also located near the boundary of a tectonic plate and hence more prone to earthquake.
What is formed by crystals and inorganic?
Minerals are formed by the arrangement of atoms in a crystalline structure and are considered inorganic substances. They are naturally occurring solids with a definite chemical composition and often have a characteristic crystal form. Minerals are essential building blocks of rocks and are found in abundance in the Earth's crust.
What did Alfreda Wagner use to support his theory on continental drift?
he told them they drifted apart because they were together
Does Connecticut have earthquakes?
I guess the geology is old and the plates are relatively stable. However, I grew up in the Middletown-Portland, Connecticut, area and there are interesting phenomena around that part of the state. The "Moodus Noises" exist and have been witnessed by hundreds of people going back to colonial times. The most recent explanation seems to be small earthquakes. Job's Pond in Portland rises and falls many feet over the space of a year with no relation to the amount of rainfall. (The pond has been renamed to _____ Lake.) There is an area in Portland (it's probably a housing development now) where the ground moves and shakes. Old time local people used to talk about it. I experienced it once myself when I parked there with a college boyfriend and the car began to rock like a small boat in a storm. Does anyone know more?
Seismic moment (M0)is a measurement of the amount of energy released along a fault rupture surface when an earthquake occurs. It is used in the calculation of a value on the moment magnitude scale (MW).
M0 = μAD
- μ is the shear modulus of the rocks along the fault rupture zone (dyne/cm2)
- A is the area of the rupture along the fault (in cm2)
- D is the average displacement on A (in cm).
Where the moment magnitude scale value is calculated using the following equation:
MW = 2/3*log10M0-10.7
