Which of the following statement about the "seismic swarm" is correct?
1
Sequence of earthquakes that happen after a larger mainshock on a fault.
2
Series of many (sometimes thousands) low-intensity earthquakes without a discernible main shock that can occur over weeks in active geothermal areas.
3
Part of an active fault that has experienced little or no seismic activity for a long period, indicates the buildup of stresses that are useful in predicting earthquakes.
4
Earthquakes that precede larger earthquakes in the same location.