# Earthquake Engineering Questions and Answers – Terminology of Strong Motion Seismology

This set of Earthquake Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Terminology of Strong Motion Seismology”.

1. What is the flatness or sharpness of response spectrum?
a) Ratio of peak displacement-acceleration product to the square of peak velocity
b) Ratio of peak displacement-velocity product to the square of peak acceleration
c) Ratio of peak velocity-acceleration product to the square of peak displacement
d) Ratio of peak displacement-acceleration product to the cube of peak velocity

Explanation: The flatness or sharpness of the response spectrum can be defined as the ratio of peak displacement-acceleration product to the square of peak velocity (ad/v2). For most of the earthquake shaking this ratio ranges between 5-15.

2. Which of the following parameter is not used to determine the severity of ground shaking?
a) Ground Acceleration
b) Velocity
c) Displacement
d) Bending Moments

Explanation: The maximum values of displacement, velocity and ground acceleration help in determining the severity of ground shaking at any site. These values also give an idea of the period of vibration.

3. Which of the following reflects the effect of amplitude of ground motion, frequency content and effect of subsequent filtering?
a) Fourier spectrum
b) Power spectrum
c) Response spectrum
d) Time spectrum

Explanation: Response spectrum is the standard way of representing the effect of ground acceleration on structures. Response spectrum reflects the effect of amplitude of ground motion, frequency content and effect of subsequent filtering by the structure. Fourier and power spectrum represent only the frequency content.

4. What is the value of sharpness of response spectrum for harmonic motions?
a) 1/2
b) 1
c) 1/4
d) 2

Explanation: For harmonic motions, the sharpness of response spectrum is 1. The value of sharpness response for steady-state square acceleration wave is 1/2. For most of the earthquake motions which are important from engineering viewpoint, the value of sharpness response is in the range of 5-15.

5. Strong motion duration is the time interval between which of the following?
a) 5% and 95% contributions
b) 0% and 100% contributions
c) 10% and 100% contributions
d) 0% and 90% contributions

Explanation: The duration of strong motion is the time interval between which 90% of the total contribution to the energy of the accelerogram occurs. The time interval between 5% to 95% is considered as the strong motion duration.

6. The ground displacement and velocity can be acquired by differentiation of an accelerogram.
a) True
b) False

Explanation: An accelerogram is the recording of ground acceleration during an earthquake. The ground displacement and velocity can be found out by direct integration of the ground acceleration data.

7. Which of the following denotes the distribution of energy associated with each frequency?
a) Time content
b) Energy content
c) Frequency content
d) Displacement content

Explanation: Frequency content is the energy distribution with respect to each frequency. It is represented by Fourier spectrum, Power spectrum and Response spectrum. Energy content is the energy carried by ground shaking with respect to frequencies.

8. Which of the following is also known as a long-period seismograph?
a) Moment seismograph
b) Velocity seismograph
c) Displacement seismograph
d) Acceleration seismograph

Explanation: A displacement seismograph is also known as a long-period seismograph. For a displacement seismograph, the period of the pendulum is long in comparison with the period of ground motion. An acceleration seismograph is also called as a short-period seismograph.

9. Which of the following local site parameters do not influence the ground motion during an earthquake?
a) Topography of the region
b) Basin effects
c) Height of building
d) Location of fault

Explanation: The faults are located in the earth’s crust. Therefore, the fault location cannot be considered as a local site parameter. Local site parameters include the surface topography of the region, basin effects and the height of building.

10. Significant energy in the range of 0.03-30 Hz is carried by the strong ground motions.
a) True
b) False

Explanation: Strong ground motions carry substantial amount of energy connected with quaking of frequencies in the range of 0.03-30 cycles per s or Hz. Strong ground motions with energy in this range cause the maximum damage except the short-duration stray pulses which have large amplitude.

Sanfoundry Global Education & Learning Series – Earthquake Engineering.

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