Geofísica
| Resumo | The first case of Reservoir-triggered seismicity (RTS) in Brazil was reported in the early 1970s. Nowadays, the data base of RTS is comprised by 26 cases that has observed in all Brazilian geological environment, such greatest magnitude was 4.2 mb and intensity VI (MM). The reservoirs that triggered earthquakes were analyzed in relation to dam height, reservoir volume, geology, seismicity level, and stress provinces. |
| Resumo | Speleothems can provide high-quality continuous records of the direction and relative paleointensity of the geomagnetic field, combining high precision dating (with U-Th method) and rapid lock-in of their detrital magnetic particles during calcite precipitation. |
| Resumo | Speleothems are classically used to reconstruct the Holocene paleoenvironment in the continents through geochemical proxies. In recent years, these cave formations have been also scrutinised for the significance of their environmental magnetism signal. In Brazil, we have been studying a set of caves encompassing different latitudes, climate and vegetation cover. In all these caves, the magnetic mineralogy composition is shown to be fairly homogeneous across the speleothem record, usually comprising magnetite as the main magnetic mineral, but also showing some amount goethite and hematite. |
| Resumo | Recent work has highlighted the potential of speleothems as faithful recorders of the geomagnetic field. They acquire remanence almost instantly, are unaffected by post-depositional effects and can be dated with high accuracy. A ~6,000 yrs geomagnetic record was retrieved from the paleomagnetic analysis of three stalagmites (WIN1, WIN2 and WIN3) from the Wintimdouine cave in the Agadir region (Morocco). |
| Resumo | The Earth's magnetic field is rapidly decaying accompanying the growth of the South Atlantic Anomaly (SAA). The longevity and recurrence of this feature at millennial timescales is still elusive, mostly because of the scarcity of geomagnetic data in the region. |