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Location:
71 km NE of Tilichiki, Russia
Period:
20 Apr 2006 23:25:02 - 22 Apr 2006 07:21:58 (1 day 7 hours 56 minutes)
Volcanoes in 100km radius:
None
Earthquakes:
18
M 7.0+:
M 7.6; 80 km NE of Tilichiki, Russia; (20 Apr 2006) (26km from the swarm center)
No swarms nearby.
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm PS20060420.2 Near Tilichiki, Russia

A notable earthquake swarm designated PS20060420.2 occurred in the Kamchatka Peninsula of Russia, centered approximately 71 km northeast of Tilichiki. The sequence began at 23:25 UTC on 20 April 2006 and concluded at 07:21 UTC on 22 April 2006, spanning 31 hours and 56 minutes. During this period, 18 earthquakes were recorded, with the largest event registering magnitude 7.6 at a depth of 22 km.

The swarm initiated with the magnitude 7.6 mainshock, followed rapidly by a magnitude 6.1 event three minutes later. Subsequent activity included multiple events of magnitude 5.0 to 6.1 distributed over the following days. Depths ranged primarily between 9 km and 34 km, indicating shallow crustal involvement consistent with regional tectonics. The sequence featured several aftershocks clustered within the first 12 hours, including three magnitude 6.1 events at depths of 9 km, 12 km, and 10 km.

Kamchatka lies within the Pacific Ring of Fire, where the Pacific Plate subducts beneath the Okhotsk Plate along the Kuril-Kamchatka Trench. This convergent margin drives intense seismicity, with frequent moderate to great earthquakes and active volcanism. The April 2006 swarm aligns with this setting, occurring in a zone of ongoing plate convergence that has produced numerous historical events exceeding magnitude 7.

Since 2000, the region has recorded limited strong seismicity according to available records, with the 2006 magnitude 7.6 event located 80 km northeast of Tilichiki serving as the primary example. The swarm's spatial distribution, centered near this mainshock, reflects typical aftershock migration along fault structures accommodating subduction-related strain.

Analysis of the temporal pattern shows peak activity immediately following the initial large events, with magnitudes generally declining over time. Depths remained shallow throughout, supporting interpretations of brittle failure in the upper crust. Such swarms provide insights into stress transfer and fault interactions in subduction zones, though detailed modeling requires integration with broader geophysical datasets.

References

  • United States Geological Survey Earthquake Catalog
  • Kamchatka Branch of Geophysical Survey, Russian Academy of Sciences
  • SeismoSight internal swarm classification data