Jökull - 01.01.2010, Page 61

Upptyppingar seismic swarms
6543210
19
18
17
16
15
14
13
Distance along azimuth 165 [km]
D
e
p
th
[k
m
]
06Jul07
08Jul07
10Jul07
12Jul07
14Jul07
16Jul07
18Jul07
20Jul07
22Jul07
24Jul07
Figure 11. ASN double-difference relative locations fit to a plane using linear regression. A dashed, black line
depicts the best-fit plane and the view is looking along the strike direction (Table 2). The RMS misfit to the
plane is 135 m (or 114 m if the two off-axis points between 16.5 and 17.0 km are removed). Here the orien-
tation of the plane (075/49) is well defined owing to the precise alignment of the hypocentres. – Besta nálgun
við tvívíðan flöt samkvæmt afstæðum staðsetningum úr ASN mælanetinu. Svört strikalína sýnir halla flatarins,
horft er eftir strikstefnunni (tafla 2). Ferningsmeðaltal (RMS) fráviks við flötinn er 135 m (eða 114 m ef tveimur
fjarlægum punktum á 16,5 og 17,0 km dýpi er sleppt). Flöturinn er vel skilgreindur með strikstefnu 75◦ og halla
49◦.
Table 3. Station coverage and absolute location
uncertainties for the 6–24 July 2007 events de-
rived from SIL and ASN single-event locations in
HypoInverse-2000. – Afstaða stöðva og óvissa í
afstæðum staðsetningum jarðskjálfta á tímabilinu
6.–24. júlí samkvæmt SIL-kerfinu og ASN netinu.
SIL ASN
Mean Azimuthal Gap (◦) 135 82
Mean Distance to Nearest Station (km) 5.9 2.6
Mean Number of P/S Picks 16 42
Mean Absolute Horizontal Error (km) 0.5 0.3
Mean Absolute Vertical Error (km) 1.0 0.5
in the Upptyppingar area as in most regions of Ice-
land. This is due to the fortuitous installation of six
nearby stations in 2004 to monitor the formation of
the Hálslón water reservoir (Jakobsdóttir, 2008). All
six SIL stations lie within 30 km of the Upptypping-
ar events. Moreover, SIL network stations are de-
ployed in vaults whereas most of the Cambridge Uni-
versity instruments, intended for temporary deploy-
ment, were buried directly in sand, dirt and pumice.
The SIL method of deployment reduces noise levels
in the seismic signals, which allows for more precise
time picking and locations.
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