Question

An earthquake causes severe structural damage to a house located within 150 miles of the epicenter of the quake. Which of the following is the best likely description of the earthquake? A. The earthquake was less than moderate, measuring below 5.0 on the Richter scale. B. The earthquake was moderate, measuring between 5.0 and 5.9 on the Richter scale. C. The earthquake was strong, measuring between 6.0 and 6.9 on the Richter scale. D. The earthquake was major or great, measuring more than 7.0 on the Richter scale.

Short answer

Considering the distance (within 150 miles) and the severity of the damage, the most likely description of the earthquake is strong, measuring between 6.0 and 6.9 on the Richter scale (option C).

Step-by-step solution

Understand the problem

We are given that the house is within 150 miles of the epicenter and has suffered severe structural damage. Based on this information, we have to choose the most likely earthquake description using the Richter scale. Step 2: Assess each option

Evaluate the options

We have four options, each describing a different intensity range. We will assess them and determine which is most likely given the information provided. A. Less than moderate (< 5.0): Earthquakes of this intensity generally cause minor or no damage. Therefore, it is unlikely that it would cause severe structural damage to the house. B. Moderate (5.0-5.9): Moderate earthquakes can cause damage to structures but are less destructive. This might be a possibility, but we should consider the stronger options as well. C. Strong (6.0-6.9): Strong earthquakes can cause severe damage to poorly constructed buildings and significant damage to well-constructed buildings. This is a possible candidate for the given damage. D. Major or great (> 7.0): Major or great earthquakes cause widespread damage to structures, including well-constructed ones. As the damage to the house is described as severe, this is also a possible candidate. Step 3: Choose the most likely option

Select the best description

Considering the distance (within 150 miles) and the severity of the damage, the most likely descriptions of the earthquake are either strong (option C) or major/great (option D). Since the distance of the affected house is relatively close to the epicenter, we may lean towards a strong earthquake (option C) as our answer. However, without additional information, we cannot completely rule out the possibility that the earthquake was major/great (option D). Both option C and D are plausible descriptions, but given only the information provided, we can choose option C, which states the earthquake was strong, measuring between 6.0 and 6.9 on the Richter scale.

Key concepts

Earthquake Intensity

Earthquake intensity refers to the measure of shaking and energy released by an earthquake. This concept is distinct from earthquake magnitude, though they are related. The Richter scale, a common method for expressing earthquake magnitude, helps in the assessment of earthquake intensity. Magnitude is a number that characterizes the relative size of an earthquake. It is calculated using seismograph recordings.

On the Richter scale:

• Earthquakes measuring less than 5.0 are usually considered minor or less intense and typically cause minimal or no damage.
• The magnitude range from 5.0 to 5.9 is termed as moderate, where slight damage can occur to structures.
• Strong earthquakes, ranging from 6.0 to 6.9, can result in severe damage, particularly to poorly built structures.
• Magnitudes over 7.0 classify as major or great earthquakes, known for causing extensive destruction.

Understanding earthquake intensity is crucial for determining the potential impact on infrastructure and communities.

Earthquake Damage Assessment

Earthquake damage assessment involves evaluating the extent of damage caused by an earthquake to physical structures. This process is pivotal for emergency response and improving building codes and construction practices.

To perform an earthquake damage assessment, experts, including engineers and architects, analyze several factors:

• The magnitude of the quake as reported, often using the Richter scale.
• Proximity of the structure to the epicenter; damage typically decreases with distance.
• The type and construction quality of buildings; older or poorly constructed buildings usually sustain more damage.
• The geological and soil conditions of the area; softer soils can amplify shaking.

Assessments are crucial for understanding the impact of earthquakes and helping communities in planning and rebuilding affected areas.

Structural Damage Evaluation

Structural damage evaluation is the detailed analysis of buildings and infrastructure following earthquakes, aiming to determine the safety and stability of affected structures. This evaluation helps to decide whether a building should be repaired, retrofitted, or demolished.

Important components of structural damage evaluation include:

• Visual inspections to identify visible cracks, inclination, and other signs of damage.
• Testing materials strength to ensure that the remaining structure can withstand stresses.
• Utilizing technology like ground-penetrating radar and laser scanning for internal assessments.
• Comparing damage with current building codes to determine compliance and future safety mitigations.

This evaluation is essential for public safety, ensuring that buildings are either promptly secured or evacuated when necessary.