Jökull - 01.12.2007, Blaðsíða 50

Þorbjarnardóttir et al.
Figure 3. Three earthquake swarms east of the tip of the Reykjanes Peninsula. The epicenter locations are col-
or-coded according to when the swarms occurred. Blue circles denote epicenters from 31 May to 1 June, green
circles from 9–10 July and pink circles from 27–28 September. Fracture data is from Clifton and Kattenhorn
(2006). Surface fractures are denoted by black lines and eruptive fractures by red lines. – Þrjár skjálftahrinur
austan Reykjanestáar. Svartar línur tákna yfirborðssprungur og rauðar línur gossprungur.
Table 1. Felt earthquakes. – Fundnir skjálftar.
Date Time Magni- Latitude Longitude Reports from
(yyyy-mm-dd) (GMT) tude (!) (!)
2006-01-10 00:25:25 3.1 63.948 -22.111 Hafnarfjörður
2006-01-13 15:19:30 3.4 66.228 -17.121 Raufarhöfn
2006-02-10 18:00:33 4.0 66.870 -18.314 Grímsey
2006-03-06 14:31:55 4.7 63.921 -21.922 Reykjavík area, Akranes, Skorradalur
2006-05-29 05:30:15 3.2 64.017 -21.268 Hveragerði
2006-06-30 03:49:10 2.7 63.852 -22.488 Grindavík
2006-08-18 02:31:28 3.5 66.019 -18.232 Dalvík
2006-09-18 10:34:00 3.1 66.567 -18.027 Grímsey
2006-09-27 02:41:27 3.0 63.781 -22.647 Þorlákshöfn
2006-11-01 13:55:25 4.2 66.116 -17.696 Akureyri, Dalvík, Húsavík, Ásbyrgi, Hörgárdalur, Mánárbakki
2006-11-27 10:34:31 2.1 63.903 -22.056 Reykjavík
2006-12-13 04:13:31 3.0 65.636 -16.879 Mývatn
method, the majority of hypocenters formed a dense
cluster, slightly elongated in a northeasterly direction
at 7.5–9 km depth. This cluster has a slightly deeper
origin than seismicity mapped on a fault 1.5 km far-
ther west (Figure 4), which was active in June 2000
(Hjaltadóttir et al., 2005). On the other hand, seis-
micity deepens eastwards (Hjaltadóttir and Vogfjörð,
2005). The 6 March mainshock is the largest earth-
quake in the area since August 2003, when an in-
tense mainshock-aftershock sequence took place west
of the lake with a magnitude 5 mainshock, followed
by over a thousand aftershocks at depths of 1.5–5 km
(Vogfjörð et al., 2004).
48 JÖKULL No. 57