Simplify the following text for a Grade 12 native English-speaking person.
Original: Officials said hundreds of volcanic earthquakes had been recorded on the mountain over the weekend of 23 â `` 24 October , and that the magma had risen to about 1 kilometre ( 3,300 ft ) below the surface due to the seismic activity .
Simplified: Officials said about 500 volcanic earthquakes had been recorded on the mountain over the weekend of 23 â `` 24 October , and that the magma had risen to about 1 k below the surface due to the seismic activity .