# Measuring & Locating Quakes - PowerPoint PPT Presentation

1 / 10

Measuring & Locating Quakes. Measuring and Locating Earthquakes. Objectives. Compare and contrast earthquake magnitude and intensity and the scales used to measure each. . Explain why data from at least three seismic stations are needed to locate an earthquake’s epicenter.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Measuring & Locating Quakes

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

## Measuring & Locating Quakes

Measuring and Locating Earthquakes

### Objectives

• Compare and contrast earthquake magnitude and intensity and the scales used to measure each.

• Explain why data from at least three seismic stations are needed to locate an earthquake’s epicenter.

• Describe Earth’s seismic belts.

Vocabulary

• magnitude

• Richter scale

• movement magnitude scale

• modified Mercalli scale

Measuring and Locating Earthquakes

### Measuring and Locating Earthquakes

• More than one million earthquakes occur each year.

• More than 90 percent of earthquakes are not felt and cause little, if any, damage.

Measuring and Locating Earthquakes

### A. Measurement Scales

• 1. Richter Scale measures the magnitude of an earthquake.

• Each successive number in the scale represents an increase in seismic-wave size, or amplitude, of a factor of 10.

• Each increase in magnitude corresponds to about a 32-fold increase in seismic energy.

Measuring and Locating Earthquakes

2. Moment Magnitude Scale

• The moment magnitude scale, takes into account the size of the fault, the amount of movement along the fault, and the rock type.

3. Modified Mercalli Scale

- measures in human terms. Uses Roman numerals I.-XII to indicate the size of a quake in terms of damage done. The same quake could register differently in different areas, depending on the quality of structures in the area.

Measuring and Locating Earthquakes

### Earthquake Magnitude and Intensity

Measuring and Locating Earthquakes

### B. Earthquake Magnitude and Intensity

Depth of Focus- deeper quakes usually have less of an impact on the Earth’s surface.

Measuring and Locating Earthquakes

### D. Seismic Belts

• The majority of the world’s earthquakes occur on or near plate boundaries.

• Almost 80 percent of all earthquakes occur in the Circum-Pacific Belt.

• About 15 percent take place across southern Europe and Asia.

• Most of the remaining earthquakes occur in narrow bands that run along the crests of ocean ridges.

• A very small percentage of earthquakes happen far from tectonic plate boundaries and are distributed more or less at random.

Measuring and Locating Earthquakes