Question

What is earthquake intensity? A. a measure of energy released B. a measure of seismic risk C. a measure of damage done D. a measure of an earthquake's focus

Short answer

Option C: a measure of damage done.

Step-by-step solution

Understanding the Question

The question asks for the definition of 'earthquake intensity.' We need to understand what aspect of an earthquake the term 'intensity' refers to. The options given are various measures related to earthquakes.

Clarifying Earthquake Intensity

Earthquake intensity measures the effects or damage caused by the earthquake at specific locations. It indicates how strong the shaking is experienced by people and structures.

Identifying the Correct Option

Based on the definition of earthquake intensity as the measure of damage and shaking felt, Option C, 'a measure of damage done,' is the correct choice. Options A, B, and D refer to other aspects like energy, risk, and focus, which are not related to intensity.

Key concepts

Seismic Risk

When we talk about seismic risk, we're essentially looking at the probability of an earthquake occurring in a particular region and the possible damage it could cause. Seismic risk encompasses several factors:

• The frequency and magnitude of earthquakes in a given area.
• The vulnerability of buildings and infrastructure.
• The potential consequences for the population.

A region with frequent or historically significant earthquakes, like California, has a higher seismic risk compared to areas with rare seismic activity. Understanding seismic risk is crucial for urban planning and designing safer buildings. By assessing this risk, authorities can better prepare for future events, minimizing potential damages and saving lives.

Damage Assessment

Damage assessment is the process of evaluating the impact of an earthquake after it occurs. This step is vital for recovery and reconstruction. It involves:

• Inspecting and documenting the physical damage to buildings, roads, and other structures.
• Assessing the economic impact on a community or region.
• Estimating the time and resources needed for repairs.

H4: Types of Damage Damage can be structural, affecting the integrity of buildings, or non-structural, such as interior and equipment damages. Both types need comprehensive evaluation to ensure safety and effective rebuilding efforts. The quicker and more accurately damage is assessed, the faster a community can begin recovery efforts, restoring normalcy and preventing further issues.

Earthquake Focus

The earthquake focus, sometimes called the hypocenter, is the point within the Earth where the earthquake begins. It's the location underground where the rock breaks and seismic waves originate. H4: Understanding Earthquake Focus - The focus is located beneath the surface, and the depth can affect how the earthquake is felt on the surface. - Shallow focus earthquakes, with a depth of less than 70 km, generally cause more severe surface shaking and damage. - Deep focus earthquakes occur between 300 km and 700 km below the surface and usually cause less surface damage. The study of earthquake focus helps scientists understand the mechanics of earthquakes, aiding in more accurate seismic risk assessments and enhancing early warning systems.