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Tjörnes Fracture Zone

Zone — systems within: Tjörnes / Grímsey · Eyjafjarðaráll · Kolbeinseyjarhryggur
Points = earthquake locations in the selected window, coloured by magnitude: M3+ · M2+ · smaller (a sample if more than 800).
Earthquakes
10
Largest
M1.7
M3,0+
0
Depth range
0–24 km
Earthquakes over time
322:2003:0807:5612:4417:3222:20
Cumulative count · 10 earthquakes · total moment ≈ M2.0 · count moment
n=100M2.0022:2003:0807:5612:4417:3222:20
Depth (0 km at top). Grey: fixed depth.
0km12km24km22:2003:0807:5612:4417:3222:20
Magnitude distribution
4<161–202–303–40≥4
Depth cross-sections — color by age (orange=newest, grey=older), point size by M. Rising cluster = possible magma intrusion.
0km12km24km17.48°W17.29°W17.11°W16.92°W16.73°WE-W
0km12km24km66.11°N66.26°N66.41°N66.55°N66.70°NN-S
Earthquakes
22
Largest
M1.7
M3,0+
0
Depth range
0–24 km
Earthquakes over time
524.0725.0725.0726.0726.0726.07
Cumulative count · 22 earthquakes · total moment ≈ M2.0 · count moment
n=220M2.0024.0725.0725.0726.0726.0726.07
Depth (0 km at top). Grey: fixed depth.
0km12km24km24.0725.0725.0726.0726.0726.07
Magnitude distribution
14<181–202–303–40≥4
Depth cross-sections — color by age (orange=newest, grey=older), point size by M. Rising cluster = possible magma intrusion.
0km12km24km18.54°W18.06°W17.57°W17.09°W16.61°WE-W
0km12km24km66.04°N66.21°N66.37°N66.53°N66.70°NN-S
Earthquakes
112
Largest
M2.2
M3,0+
0
Depth range
0–24 km
Earthquakes over time
1019.0721.0722.0724.0725.0726.07
Cumulative count · 112 earthquakes · total moment ≈ M2.6 · count moment
n=1120M2.6019.0721.0722.0724.0725.0726.07
No significant hypocenter migration — activity is stationary (R²=0.01, n=112); no sign of a propagating dike. Migration shows automatically if R²≥0.30.
Depth (0 km at top). Grey: fixed depth.
0km12km24km19.0721.0722.0724.0725.0726.07
Magnitude distribution
70<1411–212–303–40≥4
Depth cross-sections — color by age (orange=newest, grey=older), point size by M. Rising cluster = possible magma intrusion.
0km12km24km19.18°W18.54°W17.89°W17.24°W16.59°WE-W
0km12km24km66.00°N66.36°N66.73°N67.09°N67.46°NN-S
Earthquakes
372
Largest
M3.1
M3,0+
1
Depth range
0–24 km
Earthquakes over time
2426.0602.0708.0714.0720.0726.07
Cumulative count · 372 earthquakes · total moment ≈ M3.3 · count moment
n=3720M3.3026.0602.0708.0714.0720.0726.07
Depth (0 km at top). Grey: fixed depth.
0km12km24km26.0602.0708.0714.0720.0726.07
Magnitude distribution
216<11441–2112–313–40≥4
Depth cross-sections — color by age (orange=newest, grey=older), point size by M. Rising cluster = possible magma intrusion.
0km12km24km19.18°W18.48°W17.77°W17.07°W16.36°WE-W
0km12km24km65.89°N66.28°N66.67°N67.07°N67.46°NN-S
Earthquakes
2984
Largest
M3.2
M3,0+
4
Depth range
0–24 km
Earthquakes over time
29226.0707.1019.1202.0314.0526.07
Cumulative count · 2984 earthquakes · total moment ≈ M3.8 · count moment
n=29840M3.8026.0707.1019.1202.0314.0526.07
Depth (0 km at top) — shallowing in the data (7.8→5.9 km). Grey: fixed depth.
0km12km24km26.0707.1019.1202.0314.0526.07
Magnitude distribution
1216<110381–2732–343–40≥4
Depth cross-sections — color by age (orange=newest, grey=older), point size by M. Rising cluster = possible magma intrusion.
0km12km24km19.89°W19.00°W18.12°W17.24°W16.36°WE-W
0km12km24km65.85°N66.27°N66.69°N67.11°N67.53°NN-S
Gutenberg-Richter b ≈ 1.28 ± 0.08 (i.e. likely 1.19–1.36, M≥1.7, n=183)
Note: before February 2026 about half of events lacked an automatic magnitude, so magnitude-dependent figures (b-value, count of M≥X) under-count earlier periods — the catalogue is not homogeneous across this window. Cumulative moment is barely affected.
Earthquakes
7534
Largest
M4.7
M3,0+
14
Depth range
0–24 km
Earthquakes over time
123926.0719.1214.0507.1002.0326.07
Cumulative count · 7534 earthquakes · total moment ≈ M4.8 · count moment
n=75340M4.8026.0719.1214.0507.1002.0326.07
Depth (0 km at top). Grey: fixed depth.
0km12km24km26.0719.1214.0507.1002.0326.07
Magnitude distribution
2322<122651–21862–3133–41≥4
Depth cross-sections — color by age (orange=newest, grey=older), point size by M. Rising cluster = possible magma intrusion.
0km12km24km19.31°W18.60°W17.88°W17.17°W16.46°WE-W
0km12km24km65.85°N66.39°N66.94°N67.49°N68.03°NN-S
Gutenberg-Richter b ≈ 1.15 ± 0.05 (i.e. likely 1.10–1.20, M≥1.7, n=450)
Note: before February 2026 about half of events lacked an automatic magnitude, so magnitude-dependent figures (b-value, count of M≥X) under-count earlier periods — the catalogue is not homogeneous across this window. Cumulative moment is barely affected.

Depth is automatic and uncertain; earthquakes alone do not show magma movement — deformation (GPS) and gas are needed. Grey points: automatic fixed-depth values. b-value computed for M≥1.5 (automatic magnitudes make lower completeness unreliable). Preliminary data.

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