Earthquake Swarm
UPSC Relevance: Environment
Definition
An earthquake swarm is a cluster of earthquakes occurring in a relatively small area without one clearly identifiable dominant mainshock.
Difference from Aftershocks
| Earthquake Swarm | Aftershock Sequence |
|---|---|
| No clear mainshock | Has a mainshock |
| Events may have similar magnitudes | Generally smaller than mainshock |
| Activity may persist | Usually declines with time |
| Can involve fluids/magma/fault slip | Usually related to mainshock fault adjustment |
Possible Causes
Fluid movement
Magma movement
Hydrothermal activity
Slow fault slip
Tectonic processes
USGS notes that fluids are an important mechanism in many swarms, though not all swarms are volcanic.
UPSC Key Pointer
Swarm ≠ necessarily volcanic eruption.
Earthquake swarms can also occur due to tectonic processes.
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