Editing Seismometer (section)

== Recording ==
[[File:Viewing of Develocorder Film.jpg|thumb|Viewing of a Develocorder film]]
[[File:Matsushiro Seismological Observatory Seismometer.jpg|thumb|Matsushiro Seismological Observatory]]
[[File:Digital seismogram.png|thumb|A Seismogram graph]]
{{further|Seismogram}}

Today, the most common recorder is a computer with an analog-to-digital converter, a disk drive and an internet connection; for amateurs, a PC with a sound card and associated software is adequate. Most systems record continuously, but some record only when a signal is detected,
as shown by a short-term increase in the variation of the signal, compared to its long-term
average (which can vary slowly because of changes in seismic noise){{Citation needed|date=July 2014}}, also known as a STA/LTA trigger.

Prior to the availability of digital processing of seismic data in the late 1970s, the records were done in a few different forms on different types of media. A "Helicorder" drum was a device used to record data into photographic paper or in the form of paper and ink. A "Develocorder" was a machine that record data from up to 20 channels into a 16-mm film. The recorded film can be viewed by a machine. The reading and measuring from these types of media can be done by hand. After the digital processing has been used, the archives of the seismic data were recorded in magnetic tapes. Due to the deterioration of older magnetic tape medias, large number of waveforms from the archives are not recoverable.<ref>{{cite web |last1=Hutton |first1=Kate |last2=Yu |first2=Ellen |title=NEWS FLASH!! SCSN Earthquake Catalog Completed!! |publisher=Seismological Laboratory, Caltech |url=http://www.data.scec.org/about/scsncatalog.pdf |access-date=4 July 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140714225025/http://www.data.scec.org/about/scsncatalog.pdf |archive-date=14 July 2014}}</ref><ref>{{cite report |last1=Fogleman |first1=Kent A. |last2=Lahr |first2=John C. |last3=Stephens |first3=Christopher D. |last4=Page |first4=Robert A. |title=Earthquake Locations Determined by the Southern Alaska Seismograph Network for October 1971 through May 1989 |date=June 1993 |publisher=United States Geological Survey |url=http://pubs.usgs.gov/of/1993/0309/}}</ref>