Source mechanism of earthquakes in Peru

The source mechanism of 19 earthquakes that occurred in Peru (1990-1996) is studied using broad band data. Focal mechanisms are obtained using polarit ies of P wave and body wave form inversion. Shallow earthquakes show comple x source time functions, intermediate and deep depth shocks have simpler on es. Stress distributions have been obtained from focal mechanisms estimated in this study and previous studies. Shallow earthquakes show reverse fault ing with an ENE-WSW to E-W oriented pressure axes. Intermediate depth shock s indicate horizontal extension on E-W direction, normal to the Peru-Chilea n trench. Earthquakes with foci at very deep depth show horizontal extensio n in the E-W direction in Peru-Brazil and N-S in Peru-Bolivia borders. This difference in stress orientation may indicate a different origin for deep activity at each region.