Sequence · 2021-08-18

M 6.9 · Observed seismic cluster · 17 km N of Port-Olry, Vanuatu

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 cluster7
M6+1
Analysis radius324 km
Observation window14 days
Largest secondary eventM 5.4
Quake Pulse · Strong sequence

What the sequence shows

After the M 6.9 reference event, Quake Pulse counts 0 M4+ event(s) in the first 24 hours and 1 in the first 7 days. Fourteen-day M4.5+ activity is about 0.8× the average equivalent derived from the previous year. The largest secondary event is M 1.5 below the reference event.

67/100Sequence score
Events in the previous 24 h0
In the first hour0
In the first 24 hours0
In the first 7 days1
Within 14 days6
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 d207Average 14-day equivalent7.9Activity / baseline ratio0.8×

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 5.4Magnitude gapM 1.5Observed duration13.1 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.

17 km N of Port-Olry, Vanuatu · 324 kmInteractive 3D view of earthquakes within 324 km of 17 km N of Port-Olry, Vanuatu.17 km N of Port-Olry, Vanuatu
17 km N of Port-Olry, Vanuatu324 km0 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

11 Felt reports · PAGER GREEN · Tsunami indicator · Intermediate

67/100
Impact and context →

M4.5+ events in cluster

MagnitudeLocationDepthTime
M 6.917 km N of Port-Olry, Vanuatu93.0 km2021-08-18 10:10:05 UTCView event →
M 4.563 km E of Lakatoro, Vanuatu160.3 km2021-08-21 18:05:18 UTCView event →
M 4.8178 km NW of Sola, Vanuatu10.0 km2021-08-26 17:53:52 UTCView event →
M 4.550 km NE of Sola, Vanuatu10.0 km2021-08-30 21:02:23 UTCView event →
M 5.136 km NNE of Sola, Vanuatu10.0 km2021-08-30 21:03:17 UTCView event →
M 4.931 km NE of Sola, Vanuatu10.0 km2021-08-30 23:24:11 UTCView event →
M 5.420 km N of Sola, Vanuatu10.0 km2021-08-31 13:26:58 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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