Location:

Period:

15 Aug 2007 23:40:57 - 19 Aug 2007 20:11:44 (3 days 20 hours 30 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

M 7.0+:

M 8.0; 41 km SW of San Vicente de Cañete, Peru; (15 Aug 2007) (34km from the swarm center)

3 swarms found nearby.

2007

PS20070816.2(71.1km)

16 Aug

8 hours

6 earthquakes

2011

PS20111028.1(112.9km)

28 Oct

4 hours

5 earthquakes

2022

PS20221029.1(92.7km)

28 Oct

1 day 6 hours

6 earthquakes

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Seismic Swarm PS20070816.1: Aftershock Sequence Following the 2007 Peru Earthquake

The seismic swarm designated PS20070816.1 occurred approximately 45 km southwest of San Vicente de Cañete, Peru, between 23:40 on 15 August 2007 and 20:11 on 19 August 2007. Over 92 hours and 30 minutes, 28 earthquakes were recorded. The sequence initiated with a magnitude 8.0 event at 39 km depth and included multiple aftershocks ranging from magnitude 4.9 to 6.0, with depths primarily between 10 km and 48 km.

This swarm represents the immediate aftershock activity associated with the M8.0 Pisco earthquake of 15 August 2007. The mainshock epicenter was located 41 km southwest of San Vicente de Cañete, placing the swarm center about 34 km from the primary rupture zone. Aftershocks clustered in a region characterized by intense crustal stress readjustment along the plate interface.

The Peruvian coast in this area lies within the Peru-Chile subduction zone, where the Nazca Plate converges with the South American Plate at a rate of approximately 6–7 cm per year. This tectonic setting produces frequent megathrust earthquakes and associated aftershock sequences. Historical records document major events in 1687, 1746, and 1868, each generating significant tsunamis and coastal damage. The 2007 mainshock ruptured a segment of the subduction interface that had previously experienced strain accumulation since the 19th century.

Geological studies indicate that the region features a mix of marine sedimentary rocks, volcanic deposits, and accreted terranes along the continental margin. The shallow to intermediate depths of the recorded events align with typical aftershock distributions in subduction environments, reflecting both interplate and intraplate faulting.

The sequence exhibited a typical decay pattern, with the largest aftershocks (magnitudes 5.8–6.0) occurring within the first 48 hours. Depths varied from very shallow (10–11 km) to mid-crustal levels (around 40–48 km), consistent with stress transfer following the main rupture. No events exceeded magnitude 6.0 after the initial day, indicating rapid release of residual strain.

Seismic monitoring in southern Peru continues to detect background activity along the same subduction segment. Updated catalogs from regional networks confirm that the 2007 sequence remains one of the most extensively recorded aftershock series in the area since instrumental recording began.

References

USGS Earthquake Catalog
Global CMT Project
Instituto Geofísico del Perú (IGP) seismic reports