Papers by Massimo Della Schiava
Programme and abstracts the Volcanological Society of Japan, 2000
Earth and Planetary Science Letters
Journal of Volcanology and Geothermal Research, 2015
Tectonic vs hydro-fracturing events Amiata volcano Seismogenic structures such as faults play a p... more Tectonic vs hydro-fracturing events Amiata volcano Seismogenic structures such as faults play a primary role in geothermal system generation, recharge and output. They are also the most susceptible to release seismic energy over fluid injection/extraction operations during anthropic exploitation. We describe the microseismic activity recorded in 2000-2001 in the Piancastagnaio geothermal field, on the SE flank of Mt. Amiata volcano, southern Tuscany, Italy. From our field observations we find that a relatively high percentage (i.e. about 5%) of the recorded events are of hydro-fracturing origin and have a distinct waveform seismic signature when compared to the recorded events of tectonic shear-fracturing origin. While hydrofracturing events are mostly concentrated around the geothermal fields, the spatial distribution of hypocenters shows a deepening and a density increase of the micro-seismic activity from the volcanic axis toward the exploited geothermal reservoir, suggesting that volcanic spreading at Amiata is still active. The study of different data-sets from different time periods together with the knowledge from Terzaghi's law that production of large quantity of pore-fluid with the associated fluid pressure reduction could augment the stress normal to faults' surfaces (and thus their resistance to slip), make us argue that the process of volcanic spreading affecting the edifice of Amiata may allow augmented accumulation of stresses on faults, eventually leading to the release of higher stress drops, once ruptures occur. The Gutenberg-Richter magnitude-frequency distribution shows that the strongest events on record have a local magnitude in the 5-5.5 M L range, for 100-year recurrence time. In conclusions, we infer that geothermal exploitation at Mt. Amiata should be closely monitored in order to understand how fluid injection/production is responsible for the hydrofracturing seismic activity and affects stress accumulation on and rupture of faults within and in the neighborhood of the geothermal fields. This understanding may allow a geothermal field management that will hopefully reduce the risk for inducing larger seismic events in the area.
Proceedings of the 7th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COMPDYN 2015), 2019
Dynamic identification is considered a powerful technique for testing the conservation status of ... more Dynamic identification is considered a powerful technique for testing the conservation status of buildings as their natural frequencies, damping and modal shapes are directly related to their rigidity and structural integrity. This issue is of crucial interest when historical structures are in area of high seismic level, as SanSepolcro city which has experienced earthquakes up to a maximum intensity of I max = X MCS scale. The dynamic response is suitable for ancient structures because is performed by measuring ambient vibrations instead of actively shaking the building. The results obtained from dynamic tests might be used to validate the assumptions used in numerical modeling in order to reduce the uncertainties related to the soil-structure interaction and to the structural parameters. In this framework, we show how an automatic identification procedure can track in real-time the dynamic response of the museum in Sansepolcro (Italy) using operational modal analysis (OMA). The dynamic characteristics, of the SanSepolcro museum and the wall supporting the mural painting of Resurrection of Christ, were identified by installing a temporary network of 10 seismic sensors. The OMA technique was performed using enhanced frequency domain decomposition (EFDD) which has allowed to detect the first four modal shapes, damping and structural frequencies. The dynamic characteristics were used to calibrate a more realistic and reliable 3D-FEM numerical model. Integrating, the results of the dynamic indetification with 3D-FEM model analysis, has provided important information to understand the complicated system of connections between the existing walls.
Journal of Volcanology and Geothermal Research, 2015
After a month-long increase in activity at the summit craters, on 24 December 2018, the Etna volc... more After a month-long increase in activity at the summit craters, on 24 December 2018, the Etna volcano experienced a short-lived lateral effusive event followed by a rapid resumption of low-level explosive and degassing activity at the summit vents. By combining space (Moderate Resolution Imaging Spectroradiometer; MODIS and SENTINEL-2 images) and ground-based geophysical data, we track, in near real-time, the thermal, seismic and infrasonic changes associated with Etna's activity during the September-December 2018 period. Satellite thermal data reveal that the fissural eruption was preceded by a persistent increase of summit activity, as reflected by overflow episodes in New SouthEast Crater (NSE) sector. This behavior is supported by infrasonic data, which recorded a constant increase both in the occurrence and in the energy of the strombolian activity at the same crater sectors mapped by satellite. The explosive activity trend is poorly constrained by the seismic tremor, which shows instead a sudden increase only since the 08:24 GMT on the 24 December 2018, almost concurrently with the end of the infrasonic detections occurred at 06:00 GMT. The arrays detected the resumption of infrasonic activity at 11:13 GMT of 24 December, when tremors almost reached the maximum amplitude. Infrasound indicates that the explosive activity was shifting from the summit crater along the flank of the Etna volcano, reflecting, with the seismic tremor, the intrusion of a gas-rich magma batch along a~2.0 km long dyke, which reached the surface generating an intense explosive phase. The dyke propagation lasted for almost 3 h, during which magma migrated from the central conduit system to the lateral vent, at a mean speed of 0.15-0.20 m s −1. Based on MODIS and SENTINEL 2 images, we estimated that the summit outflows erupted a volume of lava of 1.4 Mm 3 (±0.5 Mm 3), and that the lateral effusive episode erupted a minimum volume of 0.85 Mm 3 (±0.3 Mm 3). The results presented here outline the support of satellite data on tracking the evolution of volcanic activity and the importance to integrate satellite with ground-based geophysical data in improving assessments of volcanic hazard during eruptive crises.
Journal of Geophysical Research Atmospheres, 2001
Page 1. JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 106, NO. B5, PAGES 8713-8727, MAY 10 2001 Time cons... more Page 1. JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 106, NO. B5, PAGES 8713-8727, MAY 10 2001 Time constraints for modeling source dynamics of volcanic explosions at Stromboli Maurizio Ripepe Dipartimento di ...
On July 13, 2001 a summit paroxysmal eruption (with strong strombolian activity and lava overflow... more On July 13, 2001 a summit paroxysmal eruption (with strong strombolian activity and lava overflows) occurred at the SE Crater of Mount Etna volcano. It was , coincident with the start of an intense earthquake swarm. During the following three days, more than 2500 earthquakes were recorded, and a dry-fracture field began to open on the higher southern slope of
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Papers by Massimo Della Schiava