Which best describes the difference between a seismograph and seismogram? a. a seismograph is a written record of volcanic eruptions, while a seismogram is a written record of earthquakes. b. a seismograph records tectonic activity, while a seismogram records volcanic activity. c. a seismograph is the instrument that detects and records volcanic activity, while a seismogram is the written record of that activity. d. a seismograph is the instrument that detects and records movements within the earth, while a seismogram is the recording.