Hengill

Seismicity by period · derived statistics from Skjálftalísa (Icelandic Met Office)

Status (automatic)

No particular signs of unrest in the last 24 hours — 8 earthquakes recorded, within the system's normal range.

VONA (Reykjanes): Yellow (unchanged since 2025-08-05) · source

VONA = Volcano Observatory Notice for Aviation; the official Met Office colour code for aviation. Independent of Skjálfti's automatic analysis.

Depth — 3D and cross-section Hengill · last 90 days

Each dot is an earthquake, depth as the third dimension — Hengill, last 90 days. Drag the 3D view to rotate; point at a dot for details.

3D (rotatable) · depth ×2.5

Cross-section — distance along profile (km) vs depth (km)

Map (top view)

<24 klst2–7 dolderunconstrained depthsize ∝ magnitude (M)

⚠ Preliminary depths, unreliable (automatic Met Office solutions; depth often poorly constrained). events with unconstrained (default) depth shown as open rings — not real structure. For illustration, not analysis.

Volcanic system in SW Iceland with major geothermal activity (Hellisheiði and Nesjavellir power plants). Last erupted ~1900 years ago (the Sandey crater in Þingvallavatn); frequent quakes tied to geothermal activity and the plate boundary. (overview — more at vedur.is) · circle on the map = rough outline of the system (radius).

📜 Did you know?

Hellisheiði (303 MW) and Nesjavellir (120 MW) power plants together produce about 15% of Iceland's electricity and more than half of its geothermal power. The last lava eruption was Nesjahraun ~150 AD (a fissure eruption from Hengill north into Þingvallavatn), but the area is among Iceland's most seismically active.

Historical eruptions in the system — points colored by size, blue circle shows where we are now in time.

❓ What if Hengill stirs?

Likely scenario: A swarm of M3-5 earthquakes (common — Hengill is one of Iceland's most seismically active areas, often linked to geothermal fluids or reinjection at Hellisheiði). An eruption is UNLIKELY — the last was Nesjahraun ~150 AD (a fissure eruption north to Þingvallavatn). No historical reawakening in the meantime. Earthquake-swarm impact: Minor damage in Hveragerði and Þorlákshöfn if the largest event is M5+; power transmission (Hellisheiði 303 MW) could be briefly disrupted. Sources: 2008 Ölfus quake (M6.3), historical seismicity.

This is not a forecast. Based on historical experience and official hazard assessments from the Met Office / Civil Protection.

☁ Air quality — SO₂

Real-time SO₂ from Environment Agency (2026-06-10T08:00 UTC). Yellow > 20 µg/m³, orange > 125 (health threshold), red > 350. Nearest stations to this system; past 24h shown for the highest.

Reykjavík (Grensás)11.8 µg/m³

Garðabær (Garðaholt)6.7 µg/m³

Hafnarfjörður (Hvaleyrarholt)5.3 µg/m³

24 h48 h7 d30 d365 d2 y

Points = earthquake locations in the selected window, coloured by magnitude: ● M3+ · ● M2+ · ● smaller (a sample if more than 800).

Earthquakes

Largest

M1.8

M3,0+

Depth range

3–7 km

Earthquakes over time

Cumulative count · 8 earthquakes · total moment ≈ M1.9 · 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

Largest

M1.8

M3,0+

Depth range

3–7 km

Earthquakes over time

Cumulative count · 12 earthquakes · total moment ≈ M1.9 · 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

352

Largest

M1.9

M3,0+

Depth range

0–16 km

Earthquakes over time

Cumulative count · 352 earthquakes · total moment ≈ M2.6 · count moment

No significant hypocenter migration — activity is stationary (R²=0.26, n=352); 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

2500

Largest

M4.5

M3,0+

Depth range

0–25 km

Earthquakes over time

Cumulative count · 2500 earthquakes · total moment ≈ M4.6 · 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.

Gutenberg-Richter b ≈ 0.81 ± 0.10 (i.e. likely 0.71–0.92, M≥1.7, n=69) · low b can accompany magma activity (small sample, interpret with caution)

Earthquakes

3759

Largest

M4.5

M3,0+

Depth range

0–25 km

Earthquakes over time

Cumulative count · 3759 earthquakes · total moment ≈ M4.6 · 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.

Gutenberg-Richter b ≈ 0.88 ± 0.11 (i.e. likely 0.77–0.99, M≥1.7, n=79)

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

5379

Largest

M4.5

M3,0+

Depth range

0–25 km

Earthquakes over time

Cumulative count · 5379 earthquakes · total moment ≈ M4.6 · 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.

Gutenberg-Richter b ≈ 0.92 ± 0.11 (i.e. likely 0.82–1.03, M≥1.7, n=88)

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.

Glossary & magnitude scale →

🌊 Volcanic tremor — The seismic tremor baseline is currently elevated and should only be compared to recent d…

IMO tremor plot (station hei). Most of the signal is weather and surf — not eruption confirmation. All stations: vedur.is.

The seismic tremor baseline is currently elevated and should only be compared to recent days since wind and waves do not reliably correlate with the measurements. (AI)

Band analysis past 9 days (from digitized RSAM values). High 2-4 Hz + low 0.5-1 Hz = possible magma-movement signal; high 0.5-1 Hz without 2-4 Hz = weather/surf.

Earthquakes in the system

Time (UTC)	Mag	Depth	Area
2026-06-10 05:03	M0.6	5.6	Önnur svæði
2026-06-10 04:44	M1.8	4.9	Önnur svæði
2026-06-10 04:44	M1.4	4.6	Önnur svæði
2026-06-10 02:08	M0.3	4.1	Önnur svæði
2026-06-10 02:05	M0.6	7.2	Önnur svæði
2026-06-09 19:46	M0.5	5.0	Önnur svæði
2026-06-09 14:07	M1.1	5.0	Reykjanesskagi capital area
2026-06-09 12:01	M0.3	2.8	Önnur svæði
2026-06-09 07:35	M-0.1	4.6	Önnur svæði
2026-06-09 07:35	M0.6	6.0	Önnur svæði
2026-06-08 14:57	M0.1	4.3	Önnur svæði
2026-06-08 13:25	M0.6	7.0	Reykjanesskagi
2026-06-08 06:15	M-0.6	3.8	Önnur svæði
2026-06-08 04:07	M-0.7	4.1	Önnur svæði
2026-06-08 03:44	M0.2	3.7	Önnur svæði
2026-06-08 01:59	M-0.2	6.5	Önnur svæði
2026-06-07 20:10	M-0.6	5.2	Önnur svæði
2026-06-07 17:53	M0.3	8.3	Önnur svæði
2026-06-07 17:48	M0.9	4.9	Önnur svæði
2026-06-07 17:48	M0.9	9.7	Önnur svæði
2026-06-07 16:01	M0.3	7.6	Önnur svæði
2026-06-07 09:57	M0.8	6.1	Önnur svæði
2026-06-07 09:57	M0.8	5.6	Önnur svæði
2026-06-06 19:45	M-0.8	5.9	Önnur svæði
2026-06-06 19:42	M-0.7	5.2	Önnur svæði
2026-06-06 19:42	M-0.6	0.0	Önnur svæði
2026-06-06 19:42	M-0.5	15.6	Önnur svæði
2026-06-06 15:46	M0.6	3.3	Önnur svæði
2026-06-06 11:48	M0.3	1.8	Önnur svæði
2026-06-06 10:07	M0.0	2.8	Önnur svæði
2026-06-06 09:43	M0.8	5.0	Önnur svæði
2026-06-06 08:23	M-0.2	4.5	Önnur svæði
2026-06-06 08:22	M0.8	6.6	Reykjanesskagi
2026-06-06 03:15	M1.4	4.6	Önnur svæði
2026-06-06 02:20	M-0.2	8.9	Önnur svæði
2026-06-05 21:56	M0.5	3.6	Önnur svæði
2026-06-05 21:47	M1.5	3.0	Önnur svæði
2026-06-05 15:41	M0.2	7.7	Reykjanesskagi
2026-06-05 12:54	M0.0	4.0	Önnur svæði
2026-06-05 12:41	M-0.3	3.1	Önnur svæði
2026-06-05 09:30	M1.0	5.8	Önnur svæði
2026-06-05 06:36	M-0.6	5.2	Önnur svæði
2026-06-05 05:07	M-1.4	5.2	Önnur svæði
2026-06-05 04:22	M-0.2	3.7	Reykjanesskagi
2026-06-05 04:06	M-1.1	5.2	Önnur svæði
2026-06-05 03:59	M-0.7	2.3	Önnur svæði
2026-06-05 03:59	M-0.5	0.1	Önnur svæði
2026-06-05 02:18	M-0.5	0.9	Önnur svæði
2026-06-05 02:18	M-0.1	0.0	Önnur svæði
2026-06-05 01:53	M0.5	6.3	Önnur svæði
2026-06-05 01:53	M0.1	5.9	Önnur svæði
2026-06-05 01:43	M1.3	3.5	Reykjanesskagi
2026-06-05 01:43	M1.1	3.2	Reykjanesskagi
2026-06-05 01:25	M-0.7	1.3	Önnur svæði
2026-06-05 01:25	M-0.7	1.4	Önnur svæði
2026-06-05 00:24	M-0.2	2.8	Önnur svæði
2026-06-04 21:53	M0.0	3.7	Önnur svæði
2026-06-04 21:12	M0.9	2.8	Önnur svæði
2026-06-04 21:12	M0.4	1.0	Reykjanesskagi
2026-06-04 20:54	M1.8	1.3	Reykjanesskagi

For the advanced — expert charts — Coulomb, migration, InSAR

🔬 Coulomb stress transfer — advanced analysis

5 earthquakes M≥3.0 in this window on this system. Such events transfer stress to neighbouring faults — some become more likely to slip, others less ("Coulomb stress transfer"). The Met Office does not publish focal mechanisms for automatically located events, so Skjálfti does not compute this itself — it requires strike/dip/rake data which is only available for M≥4.5 events in the GCMT catalogue.

For Coulomb analysis, see: USGS Coulomb 3.4 (stand-alone software) and focal mechanisms for Iceland in Global CMT.

📡 InSAR — ratsjár-aflögun yfir allt svæðið

InSAR is satellite radar from Sentinel-1: it measures deformation across the whole area, not just points like GNSS stations. Six-day interferograms reveal where the ground rose or subsided between passes. InSAR distinguishes vertical deformation (magma chamber inflation) from horizontal (dike intrusion) — GNSS alone cannot.

View latest interferograms and time-series at COMET LiCS portal (Sentinel-1, ~4-6 day lag).

System journal

Automatic snapshots and media coverage, in chronological order. Subscribe: RSS · ntfy skjalftar-hengill

Repeated × 2 since 2026-06-05 09:35:08 — last 2026-06-05 15:45:06

In the last 24 hours, 28 earthquakes were recorded in the Hengill volcanic system and activity is decreasing compared to the weekly rate, but remains normal for this area. The increase over the past week has consisted mostly of short-lived swarms rather than distributed background activity, resembling the period around February 1, 2026. The cumulative magnitude of the largest events in the last 48 hours was Mw 2.4 and the b-value was measured at 0.81 +/- 0.10. These figures are automatic preliminary results and further data can be found lower on the page.

2026-06-04 10:15:12 UTC

In the last 24 hours, 262 earthquakes were recorded in the Hengill system, showing activity similar to the past week but slightly higher than usual for this area. The increase is mostly due to short-lived swarms rather than distributed background activity, with the largest event at M1.9 and a cumulative magnitude of Mw 2.7. These automatic preliminary results most closely resemble the period around February 1, 2026, and further details on trends and land uplift are available below.

2026-06-03 16:20:13 UTC

In the last 24 hours, 320 earthquakes were recorded in the Hengill system, indicating activity similar to the past week but higher than usual for this area. The increase is mainly due to short-lived swarms rather than distributed background activity, with the largest event at M2.7 and a cumulative magnitude of Mw 3.2. These are automatic preliminary results resembling the period around February 1, 2026, and further details are available below.

2026-06-03 13:45:13 UTC

In the last 24 hours, 332 earthquakes were recorded in the Hengill system, showing activity similar to the past week but slightly higher than usual for this area. The increase is mostly due to short-lived swarms rather than distributed background activity, with the largest event at M3.8 and a cumulative magnitude of Mw 3.9. These automatic preliminary results most closely resemble the period around February 1, 2026, and further details on trends and measurements are available below.

2026-06-03 00:50:14 UTC

In the last 24 hours, 532 earthquakes were recorded in the Hengill system, indicating an increase compared to the usual rate and activity is higher than normally observed in this area. The increase consists mostly of short-lived swarms, with the largest earthquake being M4.5 and a cumulative magnitude of Mw 4.6 over the past 48 hours. These are automatic preliminary results and the activity most closely resembles the period around February 1, 2026, with further details available below on the page.

2026-06-03 00:45:13 UTC

In the last 24 hours, 537 earthquakes were recorded in the Hengill system, indicating unusually high activity for this area and an increase from previous periods. The increase is primarily due to short-lived swarms rather than distributed background activity, with the largest event at M4.5 and a cumulative magnitude of Mw 4.6. These automatic preliminary results most closely resemble conditions around February 1, 2026, and further details on trends and crustal deformation are available below.

2026-06-02 23:55:15 UTC

In the last 24 hours, 551 earthquakes were recorded in the Hengill system, indicating an increase above normal levels consisting mostly of short-lived swarms. The largest event was M4.5 with a cumulative moment of Mw 4.6 over 48 hours, and the b-value is 0.78 +/- 0.10. These automatic preliminary results most closely resemble activity around February 1, 2026. Further details are available below.

2026-06-01 21:40:14 UTC

In the last 24 hours, 907 earthquakes were recorded in the Hengill system, indicating unusually high activity for the area with the increase mainly due to short-lived swarms. The largest earthquake was magnitude M4.5 and the cumulative moment over the last 48 hours is Mw 4.6, while the b-value is 0.72 +/- 0.10. These automatic preliminary results most closely resemble the period around February 1, 2026, in terms of scope. Further charts and maps are available below.

2026-06-01 14:07:06 UTC

In the last 24 hours, 603 earthquakes were recorded in the Hengill system, representing significantly higher activity than usual for this area and an increase consisting mostly of short-lived swarms. The largest earthquake was M4.5 with a cumulative magnitude of Mw 4.6 over the past 48 hours, and the activity most closely resembles the period around February 1, 2026. These figures are automatic preliminary results, and further details can be found lower on the page.

2026-05-31 17:47:04 UTC

In the last 24 hours, 171 earthquakes were recorded in the Hengill system, indicating considerably higher activity than usual for this area and an increase from previous days. The largest earthquake was magnitude M3.2 with a cumulative moment of Mw 3.4 over the past 48 hours, though results are automatic preliminary estimates. The activity is characterized by distributed background seismicity rather than distinct swarms and most closely resembles the period around January 30, 2026. Further details on trends and measurements are available below.

2026-05-31 14:47:03 UTC

In the last 24 hours, 73 earthquakes were recorded in the Hengill system, indicating considerably higher activity than usual for this area and an increase from previous days. The activity is characterized by distributed background seismicity rather than swarms and most closely resembles the period around June 8, 2024. The largest earthquake was M2.7, and these are automatic preliminary results where depth is unreliable. Further details on trends and maps can be found lower on the page.

2026-05-31 12:47:03 UTC

In the last 24 hours, 62 earthquakes were recorded in the Hengill system, representing significantly higher activity than usual for this area and an increase from previous days. The activity is characterized by distributed background seismicity rather than swarms and most closely resembles the period around June 8, 2024. The largest earthquake was M2.7 with a cumulative moment of Mw 2.7 over the past 48 hours, though these figures are automatic preliminary results. Further details on trends and crustal deformation can be found lower on the page.

2026-05-31 07:07:04 UTC

In the last 24 hours, 19 earthquakes were recorded in the Hengill system, indicating slightly higher activity than usual for this area although similar to the past week. The activity is characterized by distributed background seismicity rather than swarms and most closely resembles the period around June 8, 2024. The largest earthquake was magnitude M2.7 with a cumulative moment of Mw 2.7, and these figures are automatic preliminary results. Further details on trends and measurements can be found below.

2026-05-30 00:47:02 UTC

In the last 24 hours, 34 earthquakes were recorded in Hengill, representing an increase above the usual rate and higher activity than normally observed in this area. The trend is characterized by distributed background activity rather than distinct swarms and most closely resembles the period around July 21, 2024. The largest earthquake was M1.6 with a cumulative magnitude of Mw 1.8 over the past 48 hours, while the b-value is 3.5, reflecting a deviation from the two-year average. These results are automatic preliminary data, and further information is available below.

2026-05-29 17:47:02 UTC

In the last 24 hours, 27 earthquakes were recorded in Hengill, representing an increase above the usual rate and attributed mostly to short-lived swarms. The largest event was M1.6 with a cumulative magnitude of Mw 1.7 over the past 48 hours, and activity most closely resembles the period around July 21, 2024. These automatic preliminary results indicate higher than normal activity for this area, with further details available below.

2026-05-28 00:27:02 UTC

In the last 24 hours, 17 earthquakes were recorded in Hengill, representing an increase above the weekly average and higher activity than usual for this area. The increase consists mostly of short-lived swarms according to automatic preliminary results, with the largest earthquake in the past 48 hours being M1.1 and a cumulative magnitude of Mw 1.5. Activity most closely resembles the period around February 21, 2026, though results are automatic preliminary data and depth is unreliable. Further details on trends and maps are available below.

2026-05-27 07:07:02 UTC

In the last 24 hours, nine earthquakes were recorded in Hengill, representing an increase above the weekly average and higher activity than usual for this area. The increase consists mostly of short-lived swarms rather than distributed background seismicity, with the largest event at M1.9 and a cumulative magnitude of Mw 1.9. These automatic preliminary results resemble the period around February 18, 2026, and further details on trends are available below. Source: automatic measurements (IMO). This is not an official warning - see vedur.is.

What do the numbers mean — and what should I do?

β (swarm signal): how high activity is versus the area's 2-year average. β above 2 means an ongoing swarm. It measures activity, not a forecast of a large quake.

Cumulative moment (Mw): the combined energy of the quakes in the period. Uplift (GNSS): whether the ground is rising or sinking, mm per year — the data are a few weeks old. Some systems (e.g. Svartsengi) deform in steps during eruption cycles rather than at a steady annual rate.

Swarm character is computed for a whole volcanic belt, not a single system — it describes the belt, not necessarily this one system.

What should I do? This is automatic monitoring for information — not an official warning. Follow official information from the Icelandic Met Office and Civil Protection (112).

Data: Icelandic Met Office (Skjálftalísa API), automatic preliminary results — may change. This is not an official warning. Official warnings: vedur.is and Civil Protection (112).