Evidence about Past Earthquakes From Faults

By: Thomas Solowynsky, Tom Mulally, Victoria Flis, Omar Oregel

Faults There are many faults that tell us

different effects and are caused by earthquakes.

Faults form because of extension or compression.

In Moab, faults are not active right now.

We will explain about earthquakes and what is different between small faults and huge faults.

Extension makes normal faults Stretching of

the ground is called Extension

Extension causes normal faults to form

Identify Faults Some layers and faults are

exposed so clearly like show different kind of stones and slips. Its can tell us if its compression or extension. Or some layers and faults are in a mess and many slips. Sometime its hard to identify the stone because it was mixed up and deformation.

Earthquake Earthquakes tend to start from the

movement in aethenosphere and it will hit to lithosphere.

In the western of U.S., earthquakes can go up to magnitude 6.0 or 7.0.

Small Faults Small faults were caused by either

many small or one medium earthquakes.

In Moab and Arches National Park, small faults tend to clearly show slips and layers.

It is easy to identify kind of rocks and match the layers.

Examples of small faults

Small Faults

Slip on small faults

Slip on faults

Slip on faults

Huge Faults Earthquakes cause the rocks to

move by slip on the fault. Near the fault, the rock gets broken

into lots of pieces from power of earthquakes.

Lots of power = lots of broken rocks There is a lot of grinding close to

faults.

Huge Faults

Fault

Very Broken Rocks! Not Very Broken Rocks

Slip

More About Huge Faults Water goes through faults easily

because of cracks and broken rocks. When old age rocks are together

with younger age rocks, we must have a big fault.

Over time rain falls onto the mountain and the mountain is made more smooth shaped. This is erosion.

Huge Fault Features

Different color

Different color

Fault

FaultYoungestRocks

YoungRocks

OldestRocks

Conclusions Evidence in the field tells us that old

faults once produced earthquakes Small earthquakes

Simple cracks with small amount of slip

Large earthquakes Lots of broken rocks Large faults are easy places for water to

flow

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