On LOWER hemisphere projections the arc bows in the dip direction

One plane at a time

One plane at a time

Connect the dots

Which way is the dip?

Which way is the dip?

What is the dip?

Visualize stereonet

Rotate poles to strike line

Rotate poles to strike line

Rotate poles to strike line

Rotate poles to strike line

Rotate poles to strike line

Read off dip

Read off dip0 o

30 o

60 o

90 o

Read off dip0 o

30 o

60 o

90 o~77o

2 strike options – which one for R.H.R.?

Option 1

Option 2

2 strike options – which one for R.H.R.?

Option 2

Option 1

2 strike options – which one for R.H.R.?

Option 2

Option 1

RL

2 strike options – which one for R.H.R.?

Option 2

Option 1

RL

NO GOOD – Dip to Left

2 strike options – which one for R.H.R.?

Option 2

Option 1

2 strike options – which one for R.H.R.?

Option 2

Option 1

LR

2 strike options – which one for R.H.R.?

Option 2

Option 1

LR

CORRECT!Dip to Right

Option 2

Read it off

Option 2

Read it off0o

30o

60o

90o

120o

150o

180o

210o

240o

270o

300o

330o

Option 2

Read it off0o

30o

60o

90o

120o

150o

180o

210o

240o

270o

300o

330o

~298o

Striking 298o

Dipping 77o

You try the other plane

Dipping

~39o

Striking0o

30o

60o

90o

120o

150o

180o

210o

240o

270o

300o

330o

~190o

Striking 298o

Dipping 77o

Striking 190o

Dipping 39o

On LOWER hemisphere projections the arc bows in the dip direction

What about UPPER hemisphere?

What about UPPER hemisphere?

Arc flips to the other side – plane is dipping opposite the arc bow direction

But strike is the same

How do things move? Compression (Black) moves away

Normal Reverse

Map view

Strike-slip (left lateral)

Oblique(Normal)

Map view

More Fun at

• http://demonstrations.wolfram.com/EarthquakeFocalMechanism/

• Might need to install their “player”