Geology of Costa Rica

Geologic Hazards

• Earthquakes

• Tsunami

• Volcanism

• Slope Hazards

Earthquake Safety• You may well experience an earthquake• Earthquakes don’t kill people; Buildings kill

people• We will not be in high risk settings• Minor shaking: no hazard• Major or prolonged shaking: Get outside• Avoid buildings and power lines• Trees are well engineered seismically• If inside, get under something sturdy or brace in

a doorway.

Tsunamis

• Warning Signs– Strong earthquake on coast– Abrupt changes in sea level – up or down

• Get to high ground or inland immediately

• Do not pass Go, do not collect $200

Volcanism

• We will not go anywhere near active volcanoes or known hazardous areas.

• If activity occurs, we will evacuate immediately

• I am a volcano expert. If you see me running, try to catch up.

Slope Hazards

• Landslides due to earthquakes

• Mudflows due to heavy rains

• Get out of the way

• Get off slope if you sense movement

• Get away from streams if water level starts to rise

Rips

• When waves break parallel to a beach, rips occur

Rips, Lake Superior

Oblique Rips

A Subduction Zone

How Arcs Grow

Exotic Terranes

Fit of Continents Across the

Atlantic

The Caribbean

Opening of the North Atlantic

Yucatan Rifts Away

Volcanic Plateau Begins to Form

Plateau Encounters Subduction Zone

Yucatan Basin Opens

East Pacific Rise Approaches

Now

Serpentinite

Bedded Chert

Pillow Lava

Pillow Lava

Graywacke

Flysch