Sequence · 2025-03-21

M 6.2 · Observed seismic cluster · 88 km SSE of Adak, Alaska

Explore clusters of M4.5+ events observed around significant earthquakes. These clusters are descriptive and are not presented as earthquake predictions.

M4.5+ events in cluster11
M6+1
Analysis radius212 km
Observation window14 days
Largest secondary eventM 5.9
Quake Pulse · Strong sequence

What the sequence shows

After the M 6.2 reference event, Quake Pulse counts 8 M4+ event(s) in the first 24 hours and 9 in the first 7 days. Fourteen-day M4.5+ activity is about 4.7× the average equivalent derived from the previous year. The largest secondary event is M 0.3 below the reference event.

70/100Sequence score
Events in the previous 24 h3
In the first hour4
In the first 24 hours8
In the first 7 days9
Within 14 days10
Peak one-hour count4

Local historical context

Descriptive comparison with M4.5+ events observed in the same radius during the 365 days before the sequence.

M4.5+ events / 365 d55Average 14-day equivalent2.1Activity / baseline ratio4.7×

A ratio above 1 means denser M4.5+ activity than the average equivalent derived from the previous 365 days. It is not a risk measure or a forecast.

Reference event

Largest secondary eventM 5.9Magnitude gapM 0.3Observed duration7.1 d

Earlier events are shown as context only. They are not labelled precursors and should not be interpreted as predictive signals.

Evolving sequence map

Shows M4+ cluster events according to elapsed time after the reference event.

Detailed timeline

Dots represent M4+ events retained by the sequence detector. Dot size depends on magnitude.

Sequences are descriptive groupings based on spatial and temporal proximity. Quake Pulse does not establish a causal link between every event here and does not provide earthquake forecasts.

Quake Pulse

Main-event impact

7 Felt reports · PAGER GREEN · Tsunami indicator · Shallow

51/100
Impact and context →

M4.5+ events in cluster

MagnitudeLocationDepthTime
M 6.288 km SSE of Adak, Alaska17.0 km2025-03-21 14:53:41 UTCView event →
M 5.987 km SSE of Adak, Alaska26.7 km2025-03-21 14:58:28 UTCView event →
M 5.085 km SSE of Adak, Alaska35.0 km2025-03-21 15:03:25 UTCView event →
M 4.678 km SSE of Adak, Alaska35.0 km2025-03-21 15:12:39 UTCView event →
M 4.592 km SSE of Adak, Alaska35.0 km2025-03-21 15:46:32 UTCView event →
M 4.593 km SSE of Adak, Alaska28.7 km2025-03-21 17:47:39 UTCView event →
M 4.679 km SSE of Adak, Alaska26.2 km2025-03-21 19:42:34 UTCView event →
M 5.688 km SSE of Adak, Alaska20.0 km2025-03-22 09:49:21 UTCView event →
M 4.986 km SSE of Adak, Alaska20.9 km2025-03-22 12:59:19 UTCView event →
M 4.5108 km SSE of Adak, Alaska10.0 km2025-03-23 14:18:55 UTCView event →
M 4.922 km NNW of Atka, Alaska123.0 km2025-03-28 16:08:49 UTCView event →

Interpretation

Explore clusters of M4.5+ events observed around significant earthquakes. These clusters are descriptive and are not presented as earthquake predictions. Historical small-earthquake detection varies through time. Long-term comparisons are most robust at higher magnitude thresholds.

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