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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
7
Largest
M1.3
M3,0+
0
Depth range
0–24 km
Earthquakes over time
221:0601:5406:4211:3016:1821:06
Cumulative count · 7 earthquakes · total moment ≈ M1.6 · count moment
n=70M1.6021:0601:5406:4211:3016:1821:06
Depth (0 km at top). Grey: fixed depth.
0km12km24km21:0601:5406:4211:3016:1821:06
Magnitude distribution
4<131–202–303–40≥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
19
Largest
M1.3
M3,0+
0
Depth range
0–24 km
Earthquakes over time
324.0725.0725.0726.0726.0726.07
Cumulative count · 19 earthquakes · total moment ≈ M1.8 · count moment
n=190M1.8024.0725.0725.0726.0726.0726.07
Depth (0 km at top). Grey: fixed depth.
0km12km24km24.0725.0725.0726.0726.0726.07
Magnitude distribution
14<151–202–303–40≥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
109
Largest
M2.2
M3,0+
0
Depth range
0–24 km
Earthquakes over time
1719.0721.0722.0724.0725.0726.07
Cumulative count · 109 earthquakes · total moment ≈ M2.6 · count moment
n=1090M2.6019.0721.0722.0724.0725.0726.07
No significant hypocenter migration — activity is stationary (R²=0.01, n=109); 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<1381–212–303–40≥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
369
Largest
M3.1
M3,0+
1
Depth range
0–24 km
Earthquakes over time
2426.0602.0708.0714.0720.0726.07
Cumulative count · 369 earthquakes · total moment ≈ M3.3 · count moment
n=3690M3.3026.0602.0708.0714.0720.0726.07
Depth (0 km at top). Grey: fixed depth.
0km12km24km26.0602.0708.0714.0720.0726.07
Magnitude distribution
216<11411–2112–313–40≥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
2982
Largest
M3.2
M3,0+
4
Depth range
0–24 km
Earthquakes over time
29126.0707.1019.1202.0314.0526.07
Cumulative count · 2982 earthquakes · total moment ≈ M3.8 · count moment
n=29820M3.8026.0707.1019.1202.0314.0526.07
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<110361–2732–343–40≥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 ≈ 1.27 ± 0.08 (i.e. likely 1.19–1.36, M≥1.7, n=182)
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
7531
Largest
M4.7
M3,0+
14
Depth range
0–24 km
Earthquakes over time
123326.0719.1214.0507.1002.0326.07
Cumulative count · 7531 earthquakes · total moment ≈ M4.8 · count moment
n=75310M4.8026.0719.1214.0507.1002.0326.07
Depth (0 km at top). Grey: fixed depth.
0km12km23km26.0719.1214.0507.1002.0326.07
Magnitude distribution
2322<122621–21862–3133–41≥4
Depth cross-sections — color by age (orange=newest, grey=older), point size by M. Rising cluster = possible magma intrusion.
0km12km24km19.18°W18.50°W17.81°W17.13°W16.45°WE-W
0km12km24km65.88°N66.38°N66.89°N67.40°N67.91°NN-S
Gutenberg-Richter b ≈ 1.15 ± 0.05 (i.e. likely 1.09–1.20, M≥1.7, n=449)
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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