Location:

Period:

10 Apr 2011 21:35:52 - 12 Apr 2011 05:07:41 (1 day 7 hours 31 minutes)

Volcanoes in 100km radius:

Nasudake(38km), Takaharayama(57km), Adatarayama(64km), Bandaisan(64km), Azumayama(74km), Numazawa(83km), Omanago Group(86km), Nantaisan(86km), Nikko-Shiranesan(95km), Hiuchigatake(98km)

Earthquakes:

22 swarms found nearby.

2004

PS20041023.1(160.1km)

23 Oct

1 day 12 hours

23 earthquakes

2008

PS20080507.1(159.8km)

7 May

17 hours

11 earthquakes

PS20081220.1(174.6km)

20 Dec

22 hours

6 earthquakes

2011

PS20110309.1(158.2km)

9 Mar

7 days 12 hours

159 earthquakes

PS20110311.2(199.2km)

11 Mar

21 hours

21 earthquakes

PS20110311.4(162.7km)

11 Mar

8 hours

57 earthquakes

PS20110311.3(165.3km)

11 Mar

1 day 17 hours

44 earthquakes

PS20110311.5(137.1km)

11 Mar

7 hours

10 earthquakes

PS20110312.2(58.0km)

11 Mar

20 hours

6 earthquakes

PS20110313.1(153.8km)

13 Mar

3 days 13 hours

14 earthquakes

PS20110314.1(83.7km)

13 Mar

13 hours

14 earthquakes

PS20110317.1(147.6km)

16 Mar

1 day 16 hours

10 earthquakes

PS20110319.1(31.7km)

18 Mar

1 day 7 hours

6 earthquakes

PS20110320.1(152.9km)

20 Mar

1 day 4 hours

6 earthquakes

PS20110322.1(155.6km)

22 Mar

2 days 5 hours

14 earthquakes

PS20110322.3(61.6km)

22 Mar

12 hours

6 earthquakes

S20110411.2(11.8km)

11 Apr

1 day 16 hours

35 earthquakes

2014

PS20140711.1(185.1km)

11 Jul

13 minutes

5 earthquakes

2016

PS20161121.1(80.3km)

21 Nov

20 hours

11 earthquakes

S20161122.1(101.8km)

21 Nov

2 days 0 hours

42 earthquakes

2021

PS20210804.1(177.9km)

3 Aug

18 hours

5 earthquakes

2022

PS20220316.1(153.4km)

16 Mar

1 hours

7 earthquakes

AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm Activity Near Ishikawa, Japan in April 2011

The seismic swarm designated PS20110411.1 was recorded 17 km SSW of Ishikawa in Japan’s Ishikawa Prefecture. It began at 21:35 on 10 April 2011 and concluded at 05:07 on 12 April 2011, spanning 31 hours and 31 minutes. During this interval seven earthquakes were detected.

The sequence opened with a magnitude 5.1 event at 35 km depth on 10 April at 21:35:52. Roughly ten hours later, on 11 April at 08:16:12, the largest shock reached magnitude 6.6 at 11 km depth. Two minutes afterward a magnitude 5.8 event occurred at 10 km depth. Subsequent events included a magnitude 5.2 quake at 48 km depth at 08:26:35, a magnitude 5.0 shock at 38 km depth at 08:58:07, a magnitude 5.5 event at 10 km depth at 11:42:35, and a final magnitude 5.9 shock at 11 km depth on 12 April at 05:07:41.

This swarm formed part of elevated regional seismicity following the magnitude 9.0 Tohoku earthquake of 11 March 2011. Static and dynamic stress changes from that megathrust event are understood to have influenced inland and offshore fault systems across central Honshu.

Ishikawa Prefecture occupies the western margin of the Noto Peninsula along the Sea of Japan coast. The peninsula is underlain by Neogene volcanic and sedimentary rocks cut by active reverse and strike-slip faults. Seismicity in the region is driven by the broader convergence of the Eurasian, Pacific, and Philippine Sea plates, with the Sea of Japan serving as a back-arc basin that accommodates modest east-west compression. Historical records document recurrent earthquake swarms in the Noto area, often linked to fluid movement along fault zones or afterslip following major regional events.

Since 1 January 2000 the area has experienced 16 documented swarms. One swarm occurred in 2004 and two in 2008; the remaining 13 took place in 2011, underscoring the anomalous activity that year.

References

SeismoSight internal swarm classification PS20110411.1
Geological Survey of Japan, AIST: Active Fault Database of Japan
USGS Earthquake Hazards Program: regional tectonic summaries for Honshu
Headquarters for Earthquake Research Promotion (Japan): Long-term evaluation of Noto Peninsula faults