Earthquakes: Measuring Intensity and Impact Quiz

Study Notes

Earthquakes: Measuring Intensity and Impact

Introduction to Earthquakes

An earthquake is a sudden, violent motion caused by movement between tectonic plates along a fault line in the Earth's crust. These movements release energy in the form of seismic waves that affect the Earth's surface.

Earthquake Intensity Scales

Measuring the intensity of an earthquake helps determine how much damage has occurred and how much danger remains for people caught in the event. The Modified Mercalli Intensity Scale (MMI) is commonly used to assess the level of shaking experienced during an earthquake. The scale ranges from I (not felt) to XII (extreme), with most earthquakes falling between II (mild) and VII (strong).

Intensity measurements are based on observable phenomena, which can range from not being able to see or feel anything (I) to significant structural damage (XII). However, the MMI is subjective and can vary based on the observer's perception. For example, people who experience an earthquake at its source might rate it lower than those farther away who feel stronger shaking.

To address this issue, a more objective method for measuring earthquakes was developed: the moment magnitude scale (Mw). Invented by Munson and his colleagues in 1979, the Mw scale uses factors like the amount of energy released and the size of the ruptured area to calculate a numerical value for the earthquake's magnitude.

Impact of Earthquakes

The impact of earthquakes on communities can vary widely depending on factors such as the magnitude, the local geology, and the time of day the quake occurs. Some immediate health impacts include trauma-related deaths and injuries from building collapse and secondary effects like drowning from tsunamis or burns from fires.

Medium-term health impacts include secondary infection of untreated wounds, increased morbidity and risk of complications related to pregnancy and childbirth due to interrupted obstetric and neonatal services, potential risk of communicable diseases, increased morbidity and risk of complications of chronic diseases due to interruption of treatment, increased psychosocial needs, and potential environmental contamination by chemical/radiological agents following destruction of industrial infrastructure.

Earthquakes can also damage health facilities and transportation, disrupting service delivery and access to care. Health workers may not be able to reach functional health facilities, and medical supplies may be lost.

Between 1998 and 2017, earthquakes caused nearly 750,000 deaths globally, more than half of all deaths related to natural disasters. More than 125 million people were affected by earthquakes during this time period, meaning they were injured, made homeless, displaced, or evacuated during the emergency phase of the disaster.

Description

Test your knowledge on measuring earthquake intensity, impact on communities, and the scales used to assess seismic activity. Explore the factors affecting earthquake intensity, the Modified Mercalli Intensity Scale (MMI), and the moment magnitude scale (Mw). Understand the various health impacts and disruptions caused by earthquakes on communities globally.