Jökull - 01.01.2017, Síða 11

Zeinab Jeddi et al.
Figure 3. Example seismograms of two eastern events at station LOD from family 1 and 2 in a) and b) re-
spectively. Waveforms of three components filtered between 4–25 Hz are shown to the left normalized by the
maximum of the vertical component in each case. The arrows mark P- and S-wave arrival times. Normalized
amplitude spectra based on the shown time window of the Z component are shown to the right. – Dæmi um
jarðskjálftalínurit tveggja skjálfta austan í Kötlu sem skráðir voru á mælistöðinni LOD (sjá mynd 2) nálægt
Loðnugiljahausi á Öldufellsleið. Efri myndin (a) sýnir skjálfta úr flokki 1 og sú neðri skjálfta úr flokki 2. Þrír
þættir skráðrar hreyfingar eru síaðir á milli 4 og 25 Hz og teiknaðir með tilliti til hámarksútslags á lóðrétta
þættinum í hvoru tilviki. Rauðar örvar sýna komutíma P og S bylgna. Myndirnar til hægri sýna útslagsróf
lóðrétta þáttarins sem fall af tíðni.
havior of the eastern seismic activity. The two
biggest swarms were detected in November 2010 in
the IMO catalog and in December 2011 with our tem-
porary network. By comparing the IMO detections
in November 2010 (14 events) and December 2011
(2 events), we can infer that the swarm in November
2010 was clearly bigger.
Magnitude
In order to estimate the local magnitudes ML we
chose a few events, the ones with the maximum num-
ber of observations, and estimated their scalar seis-
mic moment using the SIL system (Böðvarsson et al.,
1999). We then used these events to assign all events
a magnitude based on their maximum amplitude of
6 JÖKULL No. 67, 2017