Earthquakes and Volcanoes Study Guide for Test

Magma pushes up from the mantle in the middle of the Atlantic Ocean. As a result, the Atlantic Ocean is growing by several centimeters each year. How else has this magma affected the Atlantic Ocean?

It has created a long, large mountain range below the ocean's surface.

In December, 2004, an earthquake registering 9.0 on the Richter scale was recorded off the far off the coast of Sumatra. What is a common secondary effect of this type of earthquake?

A tsunami.

Area A is an area of Severe Earthquake Risk Area B is an area of Moderate Earthquake Risk Area C is an area of Low Earthquake Risk Area D is an area of Unknown Earthquake Risk To minimize the damage to buildings during an earthquake, where should new buildings be built?

Area C

Composite volcanoes are made up of layers of lava and . . .

Ash

Which accurately describes the relationship between earthquakes and volcanoes?

Earthquakes and volcanoes often are located where tectonic plates meet.

The point on earth's surface directly above the focus of an earthquake.

Epicenter

Areas on Earth's surface that lie above the places where tectonic plates meet are characterized by . . .

Frequent earthquake activity.

What is found in areas on Earth's surface that are located directly above the borders of lithosphere plates?

Frequent earthquake activity.

When magma reaches Earth's surface it becomes . . .

Lava

Most earthquakes and volcanoes occur in areas of the Pacific Ocean called "The Ring of Fire." What is the main reason for this?

Lithosphere plate boundaries are found in that area.

Use the Mercalli scale below to answer this question. Scale Felt Intensity 2 Lamps swing 4 Dishes and windows break 6 Chairs, beds, table move 8 Walls collapse 10 Roads crack, landslides 12 Total destruction You are eating dinner when the lamp above the table begins to swing. After a few seconds it stops. According to the Mercalli scale, how strong was the earthquake you felt?

Magnitude 2

Many places on Earth are shaken by earthquakes. The Pacific Coast of the United States is one such area. What causes these earthquakes?

Plate movement.

These waves are the fastest seismic waves and are the first to reach a particular location after an earthquake occurs.

Primary waves

Along these faults, the block of rock above the fault plane moves up relative to the other block.

Reverse

The San Andreas Fault in Mexico and California is watched carefully for signs of an expected earthquake. Why do scientists think an earthquake might happen there?

The San Andreas is a known major fault where pressure for lateral movement has been building for many years.