Earthquakes - class-IX

Young folded mountains are located at tectonic plate boundaries where crustal movement is most active, making them the most prone to seismic activity and earthquakes.

An isoseismic line is a line on a map connecting points where an earthquake has the same intensity. Isobars connect points of equal pressure, and isotherms connect points of equal temperature.

An earthquake is defined as the shaking or vibration of the Earth's surface caused by the release of energy from the crust, typically due to tectonic plate movement.

An earthquake is the sudden shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can be violent enough to toss people around and destroy whole cities. The seismicity or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time.

The Richter scale is a logarithmic scale, meaning each whole number increase represents a tenfold increase in measured amplitude.

Seismic waves are waves of energy that travel through the Earth's layers, and are a result of an Earthquake or a volcano that imparts low-frequency acoustic energy.

Jaisalmer is located in a relatively stable geological region compared to the highly active seismic zones of the Himalayas (Kangra, Dehra Dun, North Bihar).

The Richter magnitude scale (also Richter scale) assigns a magnitude number to quantify the size of an earthquake.

An electroscope is an early scientific instrument that is used to detect the presence and magnitude of electric charge on a body. It was the first electrical measuring instrument. The first electroscope, a pivoted needle called the versorium, was invented by British physician William Gilbert around 1600.

Amber is fossilized tree resin, which has been appreciated for its colour and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects. Amber is used as an ingredient in perfumes, as a healing agent in folk medicine, and as jewellery.

An electric current is a flow of electric charge. In electric circuits this charge is often carried by moving electrons in a wire. It can also be carried by ions in an electrolyte, or by both ions and electrons such as in an ionised gas (plasma).

Seismic waves that vibrate perpendicular to the direction of travel are S-waves (secondary waves). S-waves are shear waves and cannot travel through liquids, meaning they only travel through the solid parts of the Earth.

The Richter scale was originally devised to measure the magnitude of earthquakes of moderate size (that is, magnitude 3 to magnitude 7) by assigning a number that would allow the size of one earthquake to be compared with another.

The answer is D.

The decibel (dB) is a logarithmic unit used to express the ratio between two values of a physical quantity, often power or intensity. One of these quantities is often a reference value, and in this case, the decibel can be used to express the absolute level of the physical quantity, as in the case of sound pressure. The number of decibels is ten times the logarithm to base 10 of the ratio of two power quantities, or of the ratio of the squares of two field amplitude quantities.
The Richter scale is not a linear scale. This means that an earthquake of magnitude 6 does not have twice as destructive power as the earthquake of magnitude 3. Actually, an earthquake with magnitude 5 is ten times more destructive than an earthquake of magnitude 4. The Richter scale is a logarithmic scale.
The Meter scale is a linear scale.
Hence, (i) and (ii) are non-linear scales.

A seismograph or seismometer is an instrument which is used to record the direction of movement of earthquake waves. The first seismograph was invented in 132 A.D. by the Chinese astronomer and mathematician Chang Heng.

All three following instruments are useful in measuring the seismic activity under the earth's surface. A seismometer is an instrument that responds to ground motions, such as caused by earthquakes, volcanic eruptions. Richter scale a quantitative measure of an earthquake's magnitude. The modified Mercalli intensity scale also measures the effect of an earthquake on the Earth's surface. 

The modified Mercalli intensity scale also measures the effect of an earthquake on the Earth's surface. The Mercalli scale grades the earthquake on a 12-point scale. The intensity scale helps to analyze the data by constructing isoseismal curves, which are lines that connect points of equal intensity. 

• There are a number of ways to measure the magnitude of an earthquake. The first widely-used method, the Richter scale, was developed by Charles F. Richter in 1934. It used a formula based on the amplitude of the largest wave recorded on a specific type of seismometer and the distance between the earthquake and the seismometer.
  
• Another way to measure the strength of an earthquake is to use the Mercalli scale. Invented by Giuseppe Mercalli in 1902, this scale uses the observations of the people who experienced the earthquake to estimate its intensity.
  

Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed.

Decibel is a unit used to measure the intensity of a sound or the power level of an electrical signal by comparing it with a given level on a logarithmic scale.

The Richter magnitude scale (also Richter scale) assigns a magnitude number to quantify the size of an earthquake.

Kaleidoscope operates on the principle of multiple reflection, where two or more reflectors are placed at an angle to one another. When the eye is placed at one end of the reflectors, the original view from the aperture on the other side is multiplied into a symmetrical mosaic pattern. A two-mirror kaleidoscope yields a circular pattern isolated against a solid black background, while the three-mirror equilateral triangle type yields an infinite pattern that fills the entire visual field.

A seismometer is an instrument that responds to ground motions, such as caused by earthquakes, volcanic eruptions, and explosions. Seismometers are usually combined with a timing device and a recording device to form a seismograph

A seismograph is the instrument used to detect and record seismic waves (earthquakes).

The 2011 Tohoku earthquake in Japan was a massive event with a magnitude of 9.0 on the Richter scale.

Earthquake refers to a sudden violent shaking and vibration of the earth's surface resulting from underground movement along a fault plane or from volcanic activity. Earthquakes can cause serious destruction to property, injury to people and even death. It happens when there is sudden movement or breaking of the tectonic plates.

Answer is A.

The intensity of earthquake is measure on the richter scale.
The Richter magnitude scale was developed in 1935 by Charles F. Richter of the California Institute of Technology as a mathematical device to compare the size of earthquakes. The magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded by seismographs. Adjustments are included in the magnitude formula to compensate for the variation in the distance between the various seismographs and the epicenter of the earthquakes. On the Richter Scale, magnitude is expressed in whole numbers and decimal fractions. For example, a magnitude of 5.3 might be computed for a moderate earthquake, and a strong earthquake might be rated as magnitude 6.3. Because of the logarithmic basis of the scale, each whole number increase in magnitude represents a tenfold increase in measured amplitude; as an estimate of energy, each whole number step in the magnitude scale corresponds to the release of about 31 times more energy than the amount associated with the preceding whole number value.

The Richter magnitude scale was developed in 1935 by Charles F. Richter of the California Institute of Technology as a mathematical device to compare the size of earthquakes. The magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded by seismographs. Adjustments are included for the variation in the distance between the various seismographs and the epicenter of the earthquakes. On the Richter scale, magnitude is expressed in whole numbers and decimal fractions.

Earthquake forecasting refers to the probabilistic assessment of hazards, whereas prediction implies specifying a precise time, location, and magnitude, which is currently not scientifically possible.

• Seismology is the study of earthquakes which involves the prediction of earthquakes, hence option A is correct.
• Microbiology is the study of microorganisms and bacteriology is the study of bacteria, thus both are incorrect.

The tremors produce wave on the surface of the earth. These are called seismic waves. The waves are recorded by an instrument called the seismograph.

• Tsunamis are the catastrophic harbour waves caused by the displacement of a large amount of water at the seafloor.
• This displacement is often triggered by an earthquake at the seafloor thus option B is correct.
• Landslides are unrelated hence incorrect while Tsunamis may lead to flooding at the coastal zones. However, to chose one option the tsunami is the most direct answer to this question.