Sequence · 2021-06-20

M 6.5 · Observed seismic cluster · Kermadec Islands, New Zealand

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 cluster18
M6+1
Analysis radius260 km
Observation window14 days
Largest secondary eventM 5.9
Quake Pulse · Strong sequence

What the sequence shows

After the M 6.5 reference event, Quake Pulse counts 7 M4+ event(s) in the first 24 hours and 16 in the first 7 days. Fourteen-day M4.5+ activity is about 0.6× the average equivalent derived from the previous year. The largest secondary event is M 0.6 below the reference event.

68/100Sequence score
Events in the previous 24 h3
In the first hour2
In the first 24 hours7
In the first 7 days16
Within 14 days17
Peak one-hour count2

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 d762Average 14-day equivalent29.2Activity / baseline ratio0.6×

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 0.6Observed duration8.8 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

PAGER GREEN · Tsunami indicator · Shallow

52/100
Impact and context →

M4.5+ events in cluster

MagnitudeLocationDepthTime
M 6.5Kermadec Islands, New Zealand25.0 km2021-06-20 17:05:50 UTCView event →
M 4.5Kermadec Islands, New Zealand10.0 km2021-06-20 17:18:21 UTCView event →
M 5.4Kermadec Islands, New Zealand10.0 km2021-06-20 17:24:35 UTCView event →
M 4.7Kermadec Islands, New Zealand10.0 km2021-06-20 21:51:12 UTCView event →
M 4.6Kermadec Islands, New Zealand10.0 km2021-06-20 22:24:06 UTCView event →
M 5.9Kermadec Islands, New Zealand32.4 km2021-06-21 11:14:13 UTCView event →
M 4.6Kermadec Islands, New Zealand10.0 km2021-06-21 11:30:59 UTCView event →
M 4.6Kermadec Islands, New Zealand10.0 km2021-06-21 12:06:20 UTCView event →
M 4.5Kermadec Islands, New Zealand10.0 km2021-06-21 18:22:33 UTCView event →
M 4.8Kermadec Islands, New Zealand10.0 km2021-06-21 18:25:51 UTCView event →
M 4.5Kermadec Islands, New Zealand10.0 km2021-06-21 19:17:20 UTCView event →
M 4.9Kermadec Islands, New Zealand35.0 km2021-06-22 02:04:14 UTCView event →
M 4.7Kermadec Islands region10.0 km2021-06-24 20:20:51 UTCView event →
M 5.0Kermadec Islands, New Zealand10.0 km2021-06-26 03:04:48 UTCView event →
M 5.3Kermadec Islands region10.0 km2021-06-26 04:37:56 UTCView event →
M 5.1Kermadec Islands region10.0 km2021-06-26 22:52:37 UTCView event →
M 5.0Kermadec Islands region10.0 km2021-06-26 23:48:51 UTCView event →
M 4.7Kermadec Islands, New Zealand89.9 km2021-06-29 12:30:35 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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