The Obninsk Bulletin


Obninsk Bulletin
The "decadal" (10-day) catalog was first issued by the Moscow Institute of Physics of the Earth, beginning in 1955. This catalog was compiled by the Seismological Expedition of Geophysical Survey of the Russian Academy of Sciences (SEME GS RAS). Its publication was delayed only a few months, issued in about 50 paper copies, and sent to all the seismological centers of the former USSR. The Obninsk Observatory later became responsible for preparing the publication (now referred to as the Obninsk Bulletin), and it is now available in electronic format in its entirety.

The Bulletin includes the earthquakes recorded by numerous seismic stations (45, as of Dec. 2000) belonging to the Geophysical Survey of the Russian Academy of Sciences. At present, these stations include: 19 digital broadband stations; 2 micro-arrays; and 24 analog, three-component stations equipped with short-period, middle-period and long-period seismometers with analog galvanometer recording on photo paper. The broadband digital stations include 12 IRIS GSN stations [REF] and seven stations of Russian manufacture, known as the Seismic Digital Acquisition Station (or SDAS). The analog stations of the network are equipped with short period (SKM) and long period (SK and SKD) instruments. The data from the teleseismic network of analog stations are transferred to the Obninsk processing center in the form of station summaries in alert and operation modes by regular telephone and teletype lines. The quality of digital station operations are monitored continually, but only periodically for the analog stations. No seismic event parameters are automatically determined.

For the digital recordings, the processing and analysis are done at the Obninsk processing center (CEME GS RAS). For analog seismograms, the analysis is done by the operator of the station(s) with subsequent transfer of results to Obninsk. The decadal catalog is available after a delay of about 30 days. It includes earthquakes in Russia with M > ~4.5; for the whole of Northern Eurasia, M > ~5.0; and for the globe, with M > ~5,5. The Bulletin is sent throughout Russia and to foreign data centers (e.g., in the USA, the USGS National earthquake Information Center (NEIC), and in the U.K., the International Seismological Center (ISC)). Currently, the Obninsk Bulletin (through 1999) consists of about 41,550 earthquakes, worldwide. About 16,600 events are in the region roughly from 34-90N and 00-195E, including the former USSR and surrounding areas.

The Obninsk Bulletin reports origin times, coordinates, depth and magnitudes. Three magnitudes are traditionally reported: a surface wave magnitude MLH; a P- wave magnitude from short-period instruments (Mpsp; earlier called MPVA) and a long-period P-wave (Mplp, earlier called MPVB). Most events have no magnitudes; these are usually at about 4 < M < 4.5. The intensity data published in the Obninsk Bulletin are taken only from seismic stations as "alert" information, and not included in our composite regional catalogs.