Understanding Earthquakes

The video discusses the complexities of measuring and comparing earthquakes globally. It highlights the limitations of the Richter Scale, which was developed using data from California, and introduces the moment magnitude scale as a more comprehensive measure. The video explains how seismic waves behave differently depending on regional geology, using examples from the US, India, and Indonesia. It also explores how local geological conditions, such as sediment layers, can amplify the intensity of shaking, affecting the perceived strength of earthquakes.

Why do earthquakes in the eastern US feel more intense than those in the west?

• Because the eastern US has more frequent earthquakes.

• Because the eastern US uses a different measurement scale.

• Due to the novelty of earthquakes in the east.

• Because seismic waves travel farther in the east due to the geology.

What is a key limitation of the Richter Scale?

• It only measures earthquakes in the eastern US.

• It was developed using data from a single type of seismograph in California.

• It cannot measure earthquakes above magnitude 7.

• It is not logarithmic.

How does the moment magnitude scale improve upon the Richter Scale?

• It uses a single seismograph reading.

• It is not logarithmic.

• It is only applicable to California earthquakes.

• It considers multiple seismograph readings and physical properties of the fault.

What affects how far seismic waves travel from an earthquake's epicenter?

• The height of nearby mountains.

• The time of day the earthquake occurs.

• The type of rocks the waves travel through.

• The color of the soil.

Why was the shaking from the 2011 Virginia earthquake felt over a greater distance than the 2014 Napa earthquake?

• The Napa earthquake occurred at night.

• The Virginia earthquake was stronger.

• The geology in Virginia allows seismic waves to travel farther.

• Virginia is closer to the ocean.

What is an intraplate earthquake?

• An earthquake that only affects oceanic regions.

• An earthquake that occurs at a tectonic plate boundary.

• An earthquake that is not felt by humans.

• An earthquake that occurs within a tectonic plate.

How does local geology affect the intensity of earthquake shaking?

• The color of the soil determines shaking intensity.

• Softer sediments can amplify shaking intensity.

• It has no effect on shaking intensity.

• Harder rocks always reduce shaking intensity.

What is the 'jello effect' in the context of earthquakes?

• The way seismic waves travel faster through solid rock.

• The movement of tectonic plates during an earthquake.

• The amplification of shaking in areas with soft sediments.

• The tendency of buildings to collapse during an earthquake.

Why do cities built on plains and basins experience more intense shaking?

• Because they are closer to the epicenter.

• Due to the geological amplification of seismic waves.

• Because they have more buildings.

• Because they are farther from tectonic plate boundaries.

What is the modified Mercalli scale used for?

• Predicting future earthquakes.

• Measuring the depth of an earthquake's epicenter.

• Classifying the intensity of shaking felt during an earthquake.

• Measuring the magnitude of an earthquake.