Jökull - 01.12.1984, Síða 20

KVISKER MAY 28.1983 42dB

1 mln
Fig. 5. A part of the seismogram of May 28, 1983, from the station KV at a distance of 65 km from
Grímsvötn, showing the end of the earthquake swarm and the increasing amplitude of the volcanic
tremor following it. Tremor bursts are seen, superimposed on the background tremor.
5. mynd. Hluti skjálftarits 28. maí 1983 úr mælinum á Kvískerjum (KV) sem er í um 65 km fjarlœgð frá
Grímsvötnum. Sjá má síðustu kippina í skjálftahrinunni og vaxandi gosóróa eftir að hentii lýkur.
Óróahviður, sem standa í nokkrar mínútur, bœtast ofan á óróa með nokkuð jöfnu útslagi. Gosið hófst
líklega um það bil sem hrinunni lauk og órói hófst.
in Fig. 1) at a distance of 65 km from Grímsvötn.
The amplitude was relatively small and constant
during the first three hours, but then the ampli-
tude became variable, as if bursts of tremor were
superimposed on the background tremor. The
bursts were of different duration, from less than
one to nine minutes. The interval between them
was also quite variable during the first 12 hours,
but became more regular. An example of a
seismogram with typical tremor bursts is shown in
Fig. 5. The main characteristics of the tremor
bursts and the background tremor are summa-
rized in Table 1. The time history of the tremor
bursts is shown in Fig. 6, where the duration and
maximum amplitude of each burst is indicated on
a time axis. Here we see that the tremor activity
18 JÖKULL 34. ÁR