one of mainly low-magnitude quakes have been recorded . Such groups of quakes are called swarms . Similar swarms . They are happening in and around a national wildlife refuge in California . Seismologists record swarms on a regular basis ; in 1968 there was Hundreds in Nevada .
one of mainly low-magnitude quakes have been recorded . Such groups of quakes are called swarms . They are happening in and around a national wildlife refuge in California . Seismologists record swarms on a regular basis ; in 1968 there was Hundreds in Nevada .