A new synthesis of Pyrenean seismicity and its tectonic implications

Decoupled flexure in the South Pyrenean Foreland

“…For seismogenic layer thickness, published earthquake epicenters for this area [Souriau and Pauchet, 1998] show very low seismicity in the Ebro basin and that no earthquakes larger than magnitude 2 have occurred in the immediate area of our study since 1989. In addition, focal depths for the shallow earthquakes in this area (A. Souriau, personal communication, 1999) are too poorly constrained to indicate a seismogenic gap.…”

Fault-Related Controls on Upward Hydrothermal Flow: An Integrated Geological Study of the Têt Fault System, Eastern Pyrénées (France)

“…In addition, reverse faulting affects Quaternary sediments of the Cerdagne basin [58,66], while normal faulting affects post-Pliocene terraces near the Conflent segment [65]. Present-day moderate seismicity (i.e., magnitudes ranging from 2 to 4) is observed in the area [58] with an alignment of hypocenters along the Têt fault [49]. The stress tensor is either strike-slip or compressive, with a maximum horizontal compression between NE-SW [58] and N-S [66].…”

“…The fault scarp, culminating at around 3000 m, forms a high topographic gradient able to induce isotherm disturbance without the presence of an abnormal heat source. Moderate microseismicity [49] may maintain open hydrothermal conduits. Consequently, the Têt fault hydrothermal system is ideal for an integrated study of fault controls on upward hot fluid flow.…”

Identifying an asperity through 3‐D Mapping of the frequency‐magnitude distribution

“…Independent evidence can be gathered to support this assumption. First, the anomaly corresponds to a region where 'strong' earthquakes occur more frequently, on the long term, than in the surroundings [Lambert, 1997; Souriau and Pauchet, 1998]. During the XX th century, at least 8 events with intensities greater than Vl, probably 4 of which had magnitudes between 5 and 5.5, took place within 10 km from the anomaly (Fig.…”