1887

Abstract

The Vila Franca de Xira fault zone is the central sector of the OVLS fault zone, one of the major geological structures of the Lower Tagus Valley area in Portugal. Evidences previously gathered from geological and geophysical data suggest that it is an active fault zone and is responsible for the 1531 earthquake that caused extensive damages in Lisbon and the surrounding areas. However, no clear evidence of Quaternary seismic activity has been proven until now. The characterization of the fault zone in Holocenic terrains is therefore important for seismic hazard assessment. A P-wave and an S-wave seismic reflection profiles were acquired over an existing oil-industry and high-resolution P-wave seismic lines. The processing and preliminary interpretation of our data shows that S-wave data provides a superior resolution compared to the P-wave data and is the preferred geophysical method to characterize shallow faults zones in the study area. We have confirmed that faulting affects the Holocene alluvium and a vertical offset of 1-2 m was found in the S-wave data. This finding will allow a better definition of the return periods and the maximum expected earthquake magnitude of the OVLS fault zone.

Loading

Article metrics loading...

/content/papers/10.3997/2214-4609.20146999
2009-09-07
2020-09-21
Loading full text...

Full text loading...

http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609.20146999
Loading
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error