Sequence · 2021-11-10

M 6.6 · Observed seismic cluster · 177 km SE of Hirara, Japan

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 cluster4
M6+1
Analysis radius276 km
Observation window14 days
Largest secondary eventM 5.0
Quake Pulse · Notable sequence

What the sequence shows

After the M 6.6 reference event, Quake Pulse counts 2 M4+ event(s) in the first 24 hours and 3 in the first 7 days. Fourteen-day M4.5+ activity is about 3.0× the average equivalent derived from the previous year. The largest secondary event is M 1.6 below the reference event.

59/100Sequence score
Events in the previous 24 h0
In the first hour0
In the first 24 hours2
In the first 7 days3
Within 14 days3
Peak one-hour count1

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 d26Average 14-day equivalent1.0Activity / baseline ratio3.0×

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 5.0Magnitude gapM 1.6Observed duration1.2 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.

177 km SE of Hirara, Japan · 276 kmInteractive 3D view of earthquakes within 276 km of 177 km SE of Hirara, Japan.177 km SE of Hirara, JapanM 4.5 · 157 km SE of Hirara, Japan · 22.6 kmM 4.6 · 155 km SE of Hirara, Japan · 22.2 km
177 km SE of Hirara, Japan276 km2 Recent earthquakes

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

29 Felt reports · PAGER GREEN · Tsunami indicator · Shallow

62/100
Impact and context →

M4.5+ events in cluster

MagnitudeLocationDepthTime
M 6.6177 km SE of Hirara, Japan12.0 km2021-11-10 15:45:13 UTCView event →
M 4.5157 km SE of Hirara, Japan10.0 km2021-11-11 01:12:07 UTCView event →
M 4.6155 km SE of Hirara, Japan10.0 km2021-11-11 04:21:18 UTCView event →
M 5.0194 km SSE of Hirara, Japan10.0 km2021-11-11 20:53:22 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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