Tsunamis: Overview and Characteristics

Questions and Answers

Which scale is typically used to quantify the intensity of an earthquake based on its effects on people and structures?

Richter Scale

Moment Magnitude Scale

Body Wave Magnitude Scale

Modified Mercalli Intensity Scale (correct)

What is the primary purpose of measuring ground acceleration during an earthquake?

To establish the geological age of the area

To identify the seismic waves generated

To assess the potential damage to structures (correct)

To determine the depth of the earthquake's origin

How do structural responses of buildings typically change in relation to the frequency of seismic waves?

Building responses are consistent regardless of wave frequency

Buildings respond higher to lower frequency waves

Building responses increase linearly with frequency

Buildings are less affected by higher frequency waves (correct)

What is a common effect of vibrations on objects during seismic events?

Objects can be displaced or damaged by ground shaking Signup and view all the answers

Which criteria are essential for assessing damage after an earthquake?

A combination of visual assessments and engineering evaluations Signup and view all the answers

Which of the following factors does NOT influence tsunami velocity?

Wind speed on the surface Signup and view all the answers

What is the primary means of generating early warning for tsunamis?

Continuous seismic monitoring Signup and view all the answers

Which of the following is a common misconception about tsunamis and earthquakes?

All coastal earthquakes generate tsunamis. Signup and view all the answers

What is the period range of tsunami waves as stated?

10-45 minutes Signup and view all the answers

How far can tsunamis travel per hour in deep water, specifically at 4000 m depth?

700 kmph Signup and view all the answers

What should NOT be included in tsunami warning advisories?

Weather forecasts for the next week Signup and view all the answers

Which of the following disturbances can lead to the formation of tsunamis?

Volcanic activity under the sea Signup and view all the answers

Which earthquake parameter is primarily influenced by the distance from the epicenter?

Intensity Signup and view all the answers

Which scale is most commonly used to assess the intensity of shaking experienced during an earthquake?

Modified Mercalli Intensity scale Signup and view all the answers

What does the elastic rebound theory best explain about earthquakes?

The mechanism for the accumulation of strain Signup and view all the answers

What is the primary characteristic of P waves in relation to earthquake propagation?

They are longitudinal waves Signup and view all the answers

Which of the following would most likely result in higher ground acceleration during an earthquake?

Shallow focus earthquakes Signup and view all the answers

In assessing damage post-earthquake, which criterion is least likely to be used?

Tectonic plate boundaries Signup and view all the answers

Which aspect of building structural response is most critical to ensuring safety during an earthquake?

Weight distribution Signup and view all the answers

Which type of seismic waves tends to cause the most significant damage to structures?

Surface waves Signup and view all the answers

What factor is most important in determining the effectiveness of a building's response during an earthquake?

Construction techniques Signup and view all the answers

Which type of ground material is likely to amplify seismic waves and increase vibration effects on objects during an earthquake?

Clay Signup and view all the answers

Study Notes

Tsunami Overview

Tsunami is a series of gravity waves generated by large-scale disturbances in sea level over a brief time.
Common causes of tsunamis include underwater earthquakes, submarine volcanic eruptions, sediment displacement, coastal landslides, and meteor impacts.
Not all coastal earthquakes lead to tsunami events.

Tsunami Characteristics

Tsunami velocity is influenced by water depth; it travels at approximately 700 km/h at 4000 meters depth but drops to about 36 km/h at 10 meters depth.
Typical tsunami wave periods range from 10 to 45 minutes.

Early Warning System

The Ministry of Earth Science is developing an Early Warning System for Tsunamis and Storm Surges.
This system will issue timely warnings about tsunami potential, confirmation, estimated arrival times, strength forecasts, inundation extent, and cancellation warnings.
Storm Surge advisories will include forecasts and inundation extent similar to tsunami warnings.

Earthquake Insights

Earthquakes typically occur along fault lines where one side moves relative to the other, often leaving visible ground breakage.
India’s main seismic zones are located along the Himalayan range, Northeast India, Andaman-Nicobar Islands, and the Rann of Kutch region.

Epicenter Determination

The epicentral distance from a seismic station to an earthquake’s focus is calculated using the time separation of P and S wave arrivals and the ratio of their velocities.
The focus or hypocenter of an earthquake is usually situated several kilometers below the Earth’s surface.

Elastic Rebound Theory

Proposed by H. Reid, this theory explains that accumulated strain in rock on opposite sides of a fault eventually exceeds resistance, causing the fault to slip and trigger an earthquake.

Types of Seismic Waves

There are two main types of body waves:
- P waves: Primary waves that arrive first; these are compressional waves similar to sound waves and move longitudinally.
- S waves: Secondary waves that follow P waves and move shear waves perpendicularly.

Introduction to Seismology

Seismology studies elastic or sound waves generated from seismic sources, either natural or artificial, and records these waves with seismometers to produce seismograms.
Seismograms provide insights into the source's location and characteristics based on wave travel time and observed signal amplitude.

Insights from Seismology

Seismology reveals the Earth's internal structure, indicating the presence of the crust, mantle, and core.
The discipline is crucial for understanding earthquake mechanics and the resulting faulting, aiding in resource location and geophysical evolution studies.

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Description

This quiz covers the essential aspects of tsunamis, including their causes, characteristics, and the importance of early warning systems. Learn about the mechanisms behind tsunami generation, their travel speeds, and the efforts being made to predict and warn against these natural disasters.