Seismicity UNIT-V

 Seismicity UNIT-V

PART - A

1.      Define Seismology.

The term seismology is derived from Greek word seismo, which means earthquake and logos which means sciences, hence the seismology is science of earthquake.

2.      Define applied seismology.

In Applied seismology, where we can also distinguish between several branches, such as seismic prospecting i.e., the search by seismic method for economically significant occurrence of salt, oil, mineral ores. Furthermore, depth to bed rock measurements for construction purposes etc, the problem of distinguish between earthquake and explosions can be considered as another branch of seismology.

3.      Define Seismicity.

The frequency or magnitude of earthquake activity in a given area. Global seismicity maps shows that the region where seismicity is the highest correspond with the edges of the tectonic plates

4.      What does seismicity deals with?

In brief, seismology, deals with the following:

·         The practical problem of understanding, reacting and living with earthquake.

·         The use of earthquakes and other natural excitations of the earth to understand the nature of the terrestrial forces involved and structure of earth.

·         The technology of seismic prospecting.

5.      Define Seismic Waves.( Nov 2012)

Seismic waves are waves of energy that travel through the earth, for examples as a result of an earthquake, explosions, or some other process that imparts low frequency acoustic energy. Many other natural and anthropogenic sources create low amplitude waves commonly referred to as ambient vibrations. Seismic waves are studied by seismologists and geophysicists. Seismic waves fields are measured by a seismograph, geophone, hydrophone (in water), or accelerometer.

6.      What are called seismological instruments?

Many instruments have designed to measure ground shaking in detail, like

·         Seismograph

·         Accelerograph

·         Seismoscope

7.      Define Seismograph.

Elastic waves transmitted from single earthquake can be recorded all over the world using earthquake recording instruments called seismograph.

8.      Define Accelerograph.

Rate of change of velocity with time is known as acceleration and a strong motion earthquake instruments recording accelerations is called as accelerograph. The record from an accelerograph showing accelerograph as a function of time is acclerograms.

9.      Define seismoscope.

The first earthquake recorder described in any detail was an artistic device invented by the Chinese scholar Chang Heng about 132 AD. Balls were held in dragon’s mouths connected by linkages to vertical pendulum. Shaking released the balls. The instruments was seismoscope, because unlike a seismograph it could not give the complete time history of the earthquake shaking but simply the direction of the principal impulse due to earthquake.

10.  Define Faults.(May 2013)

A Fault is a planer fracture or discontinuity in a volume of rock, across which there has been significant displacement. Large faults within the earth’s crust result from the action of tectonic forces. Energy releases associated with rapid movement on active faults is the cause of most earthquakes.

11.  How is the earthquake magnitude measured?

The magnitude of most earthquakes is measured on the Richter scale invented by Charles R.Richter in 1934. The Richter magnitude is calculated from the amplitude of the largest seismic wave recorded for the earthquake, no matter what type of wave was strongest.

12.  Define Earthquake Magnitude.

Magnitude is a measurement of the energy released by an earth quake. The first earthquake-magnitude scale was the Richter scale, devised by Charles F. Richter, A seismologist at the California Institute of Technology. The Richter scale is based on the amplitude of seismic waves-the stronger the earthquake, the stronger the seismic vibrations it causes. The Richter magnitude of an earthquake is expressed as a decimal number, Such as 6, 7.

13.  Define earth quake intensity.

Intensity is a qualitative measure of the actual shaking at a location during an earthquake and assigned as roman capital numerals. There are many intensity scales. Two commonly used ones are the modified mercalli intensity (MMI) scale and the MSK Scale. Both scales are quite similar and range from I (least perceptive) to XII (Most Severe). The intensity scales are based on three features of shaking-perception by people and animals, performance of buildings and changes to natural surroundings.

14.  How are earthquake measured?

A seismometer is an instrument that senses the earth’s motion; a seismograph combines a seismometer with recording equipment to obtain a permanent record of the motion. From this record scientist can calculate how much energy was released in an earthquake, which is one way decide its magnitude. Calculations are made from several different seismograms, both close to far from an earthquake source to determine its magnitude, calculations from various seismic stations and seismographs should give the same magnitude, with only one magnitude for any given earth quake.

15.  Define Tsunamis.(Nov 2013)

A tsunami is a huge ocean wave that can travel at the speed up to 600 miles/hr (956 KM/Hr), hundreds of miles over open sea before it hits land. Sometimes incorrectly called a tidal wave, a tsunami is usually caused by an earthquake, volcanic eruption or coastal landslide.

Tsunamis is Japanese for “ Harbor wave” it is , in fact, a series of wave which travels outward on the ocean surface in all directions in a kind of ripple effect, since the wave can start out hundreds of miles long. And only a few feet high, they would not necessarily be noticeable to a passing ship or a plane flying over head.

16.  What are earthquake hazards?

Earthquakes really pose little direct danger to a person. People can’t be shaken to death by an earthquake. Some movies show scenes with the ground suddenly opening up and people are falling into fiery pits, but this just doesn’t happen in real life.

17.  How do ground conditions affect earthquake damage to buildings?

       The amplitude of seismic waves is depend on the medium through which they travel. Seismic waves hard rock masses (e.g. granite) have lower amplitudes than those that travel through soft ground such as sediments and so a building constructed on granite is less likely to be damaged.

   

18.  Mention the types of seismic waves.

There are several different kinds of seismic waves, and they all moves in different ways. The two main types of waves are body waves and surface waves. Body waves can travel the earth’s inner layers, but surface waves can only move along the surface of the planet like ripples on water earthquake radiates seismic energy as both body and surface waves.

19.  What is known as Rayleigh waves ?

   Rayleigh waves are a type of surfaces acountics waves that travels on a solids . they are produced on the earthquakes, in which case that are also known as “ground roll ”, or by others sources of seismic energy such as ocean waves an explosions or even sledgehammer impact . they can also be produced in materials by many mechanisms including by piezo-elctric trancducers , and are frequently used in non-detective testing for detecting defects. When guided in layers they are referred to as lamb waves.

20.  Name the longitudinal waves & Transverse waves.

    In a longitudinal waves the particular displacement is parallel to the direction of wave propogations . The animations show belows a one dimensional longitudinal plane waves propogating down a tube. The particles do not move down the tube with the waves , they simply oscillates back and forth about their individuals equilibrium positions . pick a single particles and watch its motions. The waves is seen as the motion of the compressed regions (ie., it is a pressure waves ) , which moves from left to right .

21.  What is Transverse Waves?

     In a Transverse Waves the particular displacements is perpendiculars to the direction of the wave propogations. The animations show below a one-dimensional transverse plane waves propogating from left to right . The particle do not move along with the waves ; they simply oscillates up and down about their equilibrium positions as the waves passes by picks a single particles and watch its motions.

22.Define The term Earthquake.

An earthquake (also known as a quake, tremor or temblor) is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time. Earthquakes are measured using observations from seismometers. The moment magnitude is the most common scale on which earthquakes larger than approximately 5 are reported for the entire globe. The more numerous earthquakes smaller than magnitude 5 reported by national seismological observatories are measured mostly on the local magnitude scale, also referred to as the Richter scale. These two scales are numerically similar over their range of validity. Magnitude 3 or lower earthquakes are mostly almost imperceptible and magnitude 7 and over potentially cause serious damage over large areas, depending on their depth. The largest earthquakes in historic times have been of magnitude slightly over 9, although there is no limit to the possible magnitude.

At the Earth's surface, earthquakes manifest themselves by shaking and sometimes displacement of the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes can also trigger landslides, and occasionally volcanic activity.

23.Define the Term Tsunamis

Tsunamis are long-wavelength, long-period sea waves produced by the sudden or abrupt movement of large volumes of water. In the open ocean the distance between wave crests can surpass 100 kilometers (62 miles), and the wave periods can vary from five minutes to one hour. Such tsunamis travel 600-800 kilometers per hour (373–497 miles per hour), depending on water depth. Large waves produced by an earthquake or a submarine landslide can overrun nearby coastal areas in a matter of minutes. Tsunamis can also travel thousands of kilometers across open ocean and wreak destruction on far shores hours after the earthquake that generated them.

Ordinarily, subduction earthquakes under magnitude 7.5 on the Richter scale do not cause tsunamis, although some instances of this have been recorded. Most destructive tsunamis are caused by earthquakes of magnitude 7.5 or more

24.What are precation step during the earthquake?

ü   Stay as safe as possible during an earthquake.

ü  Be aware that some earthquakes are actually foreshocks

ü  Minimize your movements to a few steps to a nearby safe place and stay indoors until the shaking has stopped

25. What are precation step during the earthquake If Indoor?

ü  DROPto the ground; take COVERby getting under a sturdy table or other piece of furniture; and HOLD ONon until the shaking stops.

ü   Stay away from glass, windows, outside doors and walls, and anything that could fall, such as lighting fixtures or furniture.

ü  Stay in bed if you are there when the earthquake strikes. Hold on and protect your head with a pillow, unless you are under a heavy light fixture that could fall.

ü  Use a doorway for shelter only if it is in close proximity to you and if you know it is a strongly supported, load bearing doorway.

ü  Stay inside until shaking stops and it is safe to go outside.

26. What are precation step during the earthquake If Outdoor?

ü  Once in the open, stay there until the shaking stops. The greatest danger exists directly outside buildings, at exits, and alongside exterior walls.

ü  Ground movement during an earthquake is seldom the direct cause of death or injury. Most earthquake-related casualties result from collapsing walls, flying glass, and falling objects.

27.What are  Funds  established by state government?

            (i) The state government shall, immediately after notifications issued for constituting the state authority and the District authority

(a)    The fund to be called the state Disaster Response Fund

(b)   The fund to be called the District Disaster Response Fund

(c)    The fund to be called the state Disaster Mitigation Fund

(d)   The fund to be called the District Disaster Mitigation Fund

(ii) The state government shall ensure that the funds established

(a)    Under clause (a) of sub section (i) is availbale to the state executive committee

(b)   Under Sub clause (c) of sub section (i) is available to the State Authority

(c)    Under Clause (b) and (d) of sub section (i) are available to the District authority

28.Define the term Seismology?

            Seismology is the scientific study of earthquakes and the propagation of elastic waves through the Earth. The field also includes studies of earthquake effects, such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, oceanic, atmospheric, and artificial processes (such as explosions). A related field that uses geology to infer information regarding past earthquakes is pale seismology

Earthquakes, and other sources, produce different types of seismic waves which travel through rock, and provide an effective way to image both sources and structures deep within the Earth.

Seismic Zoning map of India

Zone V                                    -Very High Risk Quakes of Magnitude 8 and greater

Zone IV                      -High Risk Quakes up to Magnitude 7.9

Zone III                      -Moderate Risk Quakes up to Magnitude 6.9

Zone II                                    -Seismic Disturbances up to Magnitude 4.9

29. Define Epidemic and Pendimic?

Contractible disease that spreads at a rapid rate through a human population can be described as an epidemic. A pandemic is an epidemic whose spread is global.

Eg: The 2002-2003 SARS pandemic

            The AIDS, epidemic

            Other Epidemic disease are Smallpox, Blackdeath, Influenza, Typhus

Causal phenomena

            Insanitary conditions, Crowding, poverty

            Ecological changes that favour vector breeding

            Non Immune persons migrate to endemic disease area

            Decline in nutritioanal status

            Contamination of water or food supply

30. Discuss about the Principles  casualties Management?

            Effective triage requires coordination among medical and non-medical organizations at the disaster site and between the site and local hospitals, Triage also implies making the most efficient use of available resources.

Good casualty distribution is particularly difficult to achieve in "diffuse" disasters, such as earthquakes and tornadoes that cover large geographic areas

31.What is called as Triage system?

ü  Traditionally, triage has been called the keystone to mass casualty management.

ü  Triage comes from the French verb, trier, which means "to sort." It evolved, perhaps as early as Napoleon's time, as a technique for assigning priorities for treatment of the injured when resources were limited. The basic concept was to do the greatest good for the greatest number of casualties.

ü  Generally, attention is given first to those with the most urgent conditions and to those who are the most salvageable. The technique is considered by many to be essential for good disaster medical care

32.Discuss the Limitation of News Media?

v  Reduced Foreign coverage

v  Focusing on Breaking events

v  Focusing on the sensational and Exceptional

v  Judging News Value

v  Perpetuating Negative Images

v  Belittling complex situations

v  Limited coverage areas

33.List out the major activities in the rehabilitation phase.

ü  Detailed Damage assessment

ü  Reconstruction Plan

ü  Resource Mobilization

ü  Rehabilitation of Orphans or widows

ü  Documentation

34.List out the principle of Disaster planning?

ü  Prepare for a moderate sized disaster

ü  Prepare for more common types of disasters

ü  Prepare for predictiable disaster tasks

ü  Adapt to Routine Emergencies

ü  Modular Expansion

ü  Cost sharing

ü  Executing the plan

35.Discuss the term Mitigation?

            The term mitigation is increasing being applied to measures which are geared to minimise the detriemetal impact of disaster upon life, property and the economic.Mitigation measures are of two kinds: Structural and Non structural. Structural mitigation includes measures to reduce the economic and social impact of hazard agents, Especially developing dams, windbreaks, terracing, and hazard – resistant building.

            Non – Structural mitigation is most commonly use to refer to policies and practices including land use policies, crop diversification and building codes and procedures for forecasting disaster.

Definition : “action taken to reduce both human suffering and property loss resulting from extreme natural phenomena”.

36. What is meant by structural mitigation?

Structural mitigation includes measures to reduce the economic and social impact of hazard agents, Especially developing dams, windbreaks, terracing, and hazard – resistant building.

37. What is meant by structural mitigation?

Non – Structural mitigation is most commonly use to refer to policies and practices including land use policies, crop diversification and building codes and procedures for forecasting disaster.

38. Discuss the technique used in Disaster Mitigation?

            The range of techniques that an authority might consider

            Engineering – Engineering Measures are those that result in stronger individual structures that are more resistant to hazards

            Spatial Planning – Many hazards are locialised with their likely effects confined to specific known areas. Ie : Floods affects flood plains and landsildes affect steep soft slopes

            Economic – A strong economic is the best protection against a future disaster. A strong economy means that more money can be spent on stronger buildings, safer sites and larger financial reserves to cope with future losses.

            Management  and Institutionalisation of Disaster Mitigation -  Requires certain organizational and procedural Measures. The time scale over which a significant reduction can be achieved in the potential impact of a disaster is medium and long term.

            Societal – The mitigation of disaster will only come about when there is a consensus that it is desirable.In many places, an individual hazard alone is not likely to result in disaster. 

Conflict Reduction – Mitigation must include conflict reduction. Conflict reduction measures must start with identifying and addressing the root cause of the conflict. The various sources of conflict could include issues of land tenure.

39. Discuss the engineering technique used in Disaster Mitigation.

Engineering – Engineering Measures are those that result in stronger individual structures that are more resistant to hazards.

40. Discuss the spatial planning technique used in Disaster Mitigation.

Spatial Planning – Many hazards are locialised with their likely effects confined to specific known areas. Ie : Floods affects flood plains and landsildes affect steep soft slopes.

39. Discuss the economic technique used in Disaster Mitigation.

Economic – A strong economic is the best protection against a future disaster. A strong economy means that more money can be spent on stronger buildings, safer sites and larger financial reserves to cope with future losses.

40. Discuss the Management  and Institutionalisation technique used in Disaster Mitigation.

Management  and Institutionalisation of Disaster Mitigation -  Requires certain organizational and procedural Measures. The time scale over which a significant reduction can be achieved in the potential impact of a disaster is medium and long term.

41. Discuss the Societal technique used in Disaster Mitigation

Societal – The mitigation of disaster will only come about when there is a consensus that it is desirable.In many places, an individual hazard alone is not likely to result in disaster.

42. Discuss the Conflict Reduction technique used in Disaster Mitigation

            Conflict Reduction – Mitigation must include conflict reduction. Conflict reduction measures must start with identifying and addressing the root cause of the conflict. The various sources of conflict could include issues of land tenure.

43.Discuss the disseminating information through the media.

            Press conference- A press conerence is held only when the organization  has something of vital importance to announce and there is somebody important available to make the announcment

            The Media Briefing – A media briefly ususally involves a small group of journalists who are likely to be interested in a topic of concern to both sides.

            Press Release – A press release should be considered only when the organization has a newsworthy announcement to make.

            One to one Interviews – Privare interviews are generally much-sought after by journalists, although organizations, seeking to disseminate information to a particular audience concering an issue of special concern.

44. What do you meant by press conference?

Press conference- A press conerence is held only when the organization  has something of vital importance to announce and there is somebody important available to make the announcement.

45. What do you meant by media briefing?

The Media Briefing – A media briefly ususally involves a small group of journalists who are likely to be interested in a topic of concern to both sides.

46. What do you meant by press release?

Press Release – A press release should be considered only when the organization has a newsworthy announcement to make.

47. What do you meant by one to one interview?

One to one Interviews – Privare interviews are generally much-sought after by journalists, although organizations, seeking to disseminate information to a particular audience concering an issue of special concern.

48. Give the example for Epidemic.

Contractible disease that spreads at a rapid rate through a human population can be described as an epidemic.

            Eg: The AIDS, epidemic.

            Other Epidemic disease are Smallpox, Blackdeath, Influenza, Typhus

49. Give the example for Pandemic.

A pandemic is an epidemic whose spread is global

             Eg: The 2002-2003 SARS pandemic.

50. Classify the seismic zone.

Zone V                                    -Very High Risk Quakes of Magnitude 8 and greater

Zone IV                      -High Risk Quakes up to Magnitude 7.9

Zone III                      -Moderate Risk Quakes up to Magnitude 6.9

Zone II                                    -Seismic Disturbances up to Magnitude 4.9

Part-B

1.      What are seismic waves ? explain in  details. .(Nov 2012)

2.      Briefly explain about seismology.

3.      Define earthquake ? Explain its faults.(May 2013)

4.      How are Earthquakes Measured ?  explain in details. (May 2013)

5.      How are Earthquakes magnitude and intensity measured ? Explain in detail. .(Nov 2012)

6.      Briefly explain a case study on Tsunamis.(Nov 2012)

7.      State the impact on recently occurred in tsunami in india. Explain (May 2013)

8.      What are the factors to be considered while planning the rebuilding works after a major disaster due to earthquake.(Nov 2011)

9.      What are the cause for the tsunami 2004 which inflicted heavy loss to life and property along the coast tamilnadu? specify its epicenter and magnitude. .(Nov 2011)

10.  Briefly explain a case study on earthquake.(Nov 2012)