Active tectonics and first paleoseismological results in Faial, Picoand S. Jorge islands (Azores, Portugal)
Main Article Content
Abstract
The neotectonics of the islands of Faial, Pico and S. Jorge (Azores) is presented. Preliminary paleoseismology
data from trench exposures across three active fault zones (Lomba do Meio, Lagoa do Capitão and Pico do
Carvão faults) complement the information. Radiocarbon age constraints of paleoearthquakes suggest clustering
of surface rupturing events. Slip rates deduced from paleoseismology analysis range from 0.10 to 0.40 cm/year
and validate long-term slip rates obtained by neotectonic studies (using Pleistocene markers). The studied faults
allowed a preliminary seismic hazard assessment: magnitudes of the largest paleoearthquakes, determined from
slip per event range from Mw = 6.9 to 7.1, and maximum expected magnitudes, estimated from rupture length or
rupture area, vary from Mw = 6.4 to 6.8. The former Mw estimates are in closer agreement with the magnitude of
the major historic and instrumental seismic events in the archipelago, even though the used empirical relations
between magnitude and rupture parameters may not be the most adequate due to the unique tectonic setting of
Azores.
data from trench exposures across three active fault zones (Lomba do Meio, Lagoa do Capitão and Pico do
Carvão faults) complement the information. Radiocarbon age constraints of paleoearthquakes suggest clustering
of surface rupturing events. Slip rates deduced from paleoseismology analysis range from 0.10 to 0.40 cm/year
and validate long-term slip rates obtained by neotectonic studies (using Pleistocene markers). The studied faults
allowed a preliminary seismic hazard assessment: magnitudes of the largest paleoearthquakes, determined from
slip per event range from Mw = 6.9 to 7.1, and maximum expected magnitudes, estimated from rupture length or
rupture area, vary from Mw = 6.4 to 6.8. The former Mw estimates are in closer agreement with the magnitude of
the major historic and instrumental seismic events in the archipelago, even though the used empirical relations
between magnitude and rupture parameters may not be the most adequate due to the unique tectonic setting of
Azores.
Article Details
How to Cite
Madeira, J. and Brum da Silveira, A. (2003) “Active tectonics and first paleoseismological results in Faial, Picoand S. Jorge islands (Azores, Portugal)”, Annals of Geophysics, 46(5). doi: 10.4401/ag-3453.
Issue
Section
OLD
Open-Access License
No Permission Required
Istituto Nazionale di Geofisica e Vulcanologia applies the Creative Commons Attribution License (CCAL) to all works we publish.
Under the CCAL, authors retain ownership of the copyright for their article, but authors allow anyone to download, reuse, reprint, modify, distribute, so long as the original authors and source are cited. No permission is required from the authors or the publishers.
In most cases, appropriate attribution can be provided by simply citing the original article.
If the item you plan to reuse is not part of a published article (e.g., a featured issue image), then please indicate the originator of the work, and the volume, issue, and date of the journal in which the item appeared. For any reuse or redistribution of a work, you must also make clear the license terms under which the work was published.
This broad license was developed to facilitate open access to, and free use of, original works of all types. Applying this standard license to your own work will ensure your right to make your work freely and openly available. For queries about the license, please contact ann.geophys@ingv.it.