On crustal seismicity of the Amazonian foothill of the central Peruvian Andes

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Abstract
A microearthquake survey of crustal seismicity conducted in 1985 on the Eastern Cordillera and the Amazonian foothills in Central Peru gives a description of the present tectonic activity related to the uplift of the Andes. Hypocenters on the Huaytapallana fault are shallower than 10 km, and their focal mechanism is in agreement with the fault trace corresponding to the earthquakes of 1969 and suggests a reverse strike slip movement on a plane striking N130°. An active tectonic zone is evidenced along a NW‐SE direction passing through the Amauta Subandean region. The vertical distribution of hypocenters and the comparison of shallow and deep focal mechanisms suggest a reverse fault dipping to the west. Depths vary between 0 and 20 km. and never exceed 32 km. The Huaytapallana Cordillera is uplifted by thrust faults on both sides.