active faults
Moving tectonic cracks
Active faults are fractures in the Earth's crust that have moved recently in geologic time and are likely to move again, potentially causing earthquakes.
Geologists distinguish active faults from inactive ones when assessing seismic risk for construction and land use: Building codes are stricter near active faults. "Recently" in this context typically means within the last 10,000 to 2 million years, depending on the region and regulatory framework.
Seismic ground movement
- epicenterPoint above seismic origin
- magnitudeSize or scale
- tremorInvoluntary rhythmic shaking
- aftershockSmaller quake following larger
foreshock · seismograph · seismometer · Richter · intensity · ground shaking · P-waves · S-waves
Concave carving blade
- brecciaCemented angular rock fragments
- offsetCompensate by opposing force
- deformationChange in shape
- strainExcessive stretching force
stress · fracture · fissure · outcrop · bedrock · stratigraphy · Quaternary · Holocene
Earth's crust mobility theory
- subductionPlate descending beneath another
- convergenceProcess of approaching sameness
- divergenceSeparation from common origin
- lithosphereCrust plus upper mantle
crust · mantle · continental drift · rift · trench · orogeny · strike-slip · San Andreas
Possibility of harm
- liquefactionConversion to liquid state
- landslideMass of earth falling
- tsunamiSeismic sea surge
- disasterSudden ruinous event
emergency · evacuation · vulnerability · mitigation · building codes · preparedness · resilience · damage
earthquake
Seismic ground movement
aftershock · foreshock · seismograph · seismometer · Richter · intensity · ground shaking · P-waves · S-waves · rupture
gouge
Concave carving blade
- brecciaCemented angular rock fragments
- offsetCompensate by opposing force
- deformationChange in shape
strain · stress · fracture · fissure · outcrop · bedrock · stratigraphy · Quaternary · Holocene · geomorphology
plate tectonics
Earth's crust mobility theory
- subductionPlate descending beneath another
- convergenceProcess of approaching sameness
- divergenceSeparation from common origin
lithosphere · crust · mantle · continental drift · rift · trench · orogeny · strike-slip · San Andreas · graben
risk
Possibility of harm
- liquefactionConversion to liquid state
- landslideMass of earth falling
- tsunamiSeismic sea surge
disaster · emergency · evacuation · vulnerability · mitigation · building codes · preparedness · resilience · damage · infrastructure