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
Cumulative count · 7 earthquakes · total moment ≈ M1.6 · count moment
Depth (0 km at top). Grey: fixed depth.
Magnitude distribution
Depth cross-sections — color by age (orange=newest, grey=older), point size by M. Rising cluster = possible magma intrusion.
Earthquakes
19
Largest
M1.3
M3,0+
0
Depth range
0–24 km
Earthquakes over time
Cumulative count · 19 earthquakes · total moment ≈ M1.8 · count moment
Depth (0 km at top). Grey: fixed depth.
Magnitude distribution
Depth cross-sections — color by age (orange=newest, grey=older), point size by M. Rising cluster = possible magma intrusion.
Earthquakes
109
Largest
M2.2
M3,0+
0
Depth range
0–24 km
Earthquakes over time
Cumulative count · 109 earthquakes · total moment ≈ M2.6 · count moment
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.
Magnitude distribution
Depth cross-sections — color by age (orange=newest, grey=older), point size by M. Rising cluster = possible magma intrusion.
Earthquakes
369
Largest
M3.1
M3,0+
1
Depth range
0–24 km
Earthquakes over time
Cumulative count · 369 earthquakes · total moment ≈ M3.3 · count moment
Depth (0 km at top). Grey: fixed depth.
Magnitude distribution
Depth cross-sections — color by age (orange=newest, grey=older), point size by M. Rising cluster = possible magma intrusion.
Earthquakes
2982
Largest
M3.2
M3,0+
4
Depth range
0–24 km
Earthquakes over time
Cumulative count · 2982 earthquakes · total moment ≈ M3.8 · count moment
Depth (0 km at top) — shallowing in the data (7.8→5.9 km). Grey: fixed depth.
Magnitude distribution
Depth cross-sections — color by age (orange=newest, grey=older), point size by M. Rising cluster = possible magma intrusion.
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
Cumulative count · 7531 earthquakes · total moment ≈ M4.8 · count moment
Depth (0 km at top). Grey: fixed depth.
Magnitude distribution
Depth cross-sections — color by age (orange=newest, grey=older), point size by M. Rising cluster = possible magma intrusion.
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.