Examine measurements and effects of earthquakes with references

Question 1

Intro

Answer 1

An earthquake is a vibration in the earths surface caused by a sudden release of energy beneath the crust.
Since 1950, there have been 21 major earthquakes.
There are three types of scales; Richter scale, Mercalli scale and the Moment magnitude scale.

Question 2

Richter scale

Answer 2

For the Richter scale, readings from a seismograph are recorded to determine an earthquakes magnitude.

The scale begins at 0 and there is no upper limit.

The scale is logarithmic.
This means that each step on the Richter scale represents a tenfold increase in magnitude.

For example, a 2.0 is ten million times stronger than a 1.0.

Question 3

MMS

Answer 3

The MMS or the Moment Magnitude scale is ore commonly used by seismologists.

This scale uses seismographic readings and rock movement to accurately determine the earthquakes magnitude.

This scale also is logarithmic.

The MMS readings are more accurate then the Richter scale and is used by media to report an earthquake.

Question 4

Mercalli scale

Answer 4

The Mercalli scale originally was determined by human experiences and observation.

This scale is measured on a scale of 0-12 with each step indicating a greater level of damage.

To improve its accuracy, seismologists combined observation with seismograph readings to produce the Modified Mercalli scale.

Question 5

Effects of earthquakes

Answer 5

There are many effects of earthquakes.
It can cause damage to infrastructure.
The seismic waves can cause damage to bridges and buildings.
The falling debris can cause loss of life and people can become trapped under fallen buildings.

Question 6

Tsunamis

Answer 6

Earthquakes can cause tsunamis soon after the shockwaves.
As the plate subducts, pressure can cause the underlying plate to be forced upwards.
This creates a hump of excess water which can spread at a rate of 970 km/h.

Question 7

Liquefaction

Answer 7

Liquefaction can also occur after an earthquake.
When the ground shakes, the groundwater rises upwards.
This causes the soil to take on the properties of a liquid.
Soil saturated due to liquefaction cannot support infrastructure which causes buildings to collapse.
Liquefaction can also cause gas and sewage pipes to break causing fires and contamination