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Combining stress transfer and source directivity: the case of the 2012 Emilia seismic sequence.

Convertito V, Catalli F, Emolo A - Sci Rep (2013)

Bottom Line: We find that static stress redistribution alone is not capable of explaining the locations of subsequent events.We conclude that dynamic triggering played a significant role in driving the sequence.This triggering was also associated with a variation in permeability and a pore pressure increase in an area characterized by a massive presence of fluids.

View Article: PubMed Central - PubMed

Affiliation: Istituto Nazionale di Geofisica e Vulcanologia - Osservatorio Vesuviano, Via Diocleziano 328, 80124, Napoli, Italy.

ABSTRACT
The Emilia seismic sequence (Northern Italy) started on May 2012 and caused 17 casualties, severe damage to dwellings and forced the closure of several factories. The total number of events recorded in one month was about 2100, with local magnitude ranging between 1.0 and 5.9. We investigate potential mechanisms (static and dynamic triggering) that may describe the evolution of the sequence. We consider rupture directivity in the dynamic strain field and observe that, for each main earthquake, its aftershocks and the subsequent large event occurred in an area characterized by higher dynamic strains and corresponding to the dominant rupture direction. We find that static stress redistribution alone is not capable of explaining the locations of subsequent events. We conclude that dynamic triggering played a significant role in driving the sequence. This triggering was also associated with a variation in permeability and a pore pressure increase in an area characterized by a massive presence of fluids.

No MeSH data available.


Related in: MedlinePlus

Location map of the 2012 Emilia earthquake sequence.Geographic location of the 2012 Emilia seismic sequence (Italian Seismological Instrumental and parametric Data-basE, http://iside.rm.ingv.it). Orange dots, with corresponding focal mechanisms3, represent the epicenters of the main events analysed in this study and listed in Table 1. Red dots represent the location of events 2 and 7, whose focal mechanisms have been estimated by average of the known focal mechanisms. For each event the sequential number and magnitude are also specified. Open stars indicate location of events with M > 3.0, while gray squares represent all the other earthquakes. The sequence spans a time interval of about one month and covers an area of about 60 km × 30 km. The figure was generated by using the Generic Mapping Tools (http://gmt.soest.hawaii.edu/)35. The topography is based on the ETOPO1 1 Arc-Minute Global Relief Model, http://www.ngdc.noaa.gov/mgg/global/global.html36.
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f1: Location map of the 2012 Emilia earthquake sequence.Geographic location of the 2012 Emilia seismic sequence (Italian Seismological Instrumental and parametric Data-basE, http://iside.rm.ingv.it). Orange dots, with corresponding focal mechanisms3, represent the epicenters of the main events analysed in this study and listed in Table 1. Red dots represent the location of events 2 and 7, whose focal mechanisms have been estimated by average of the known focal mechanisms. For each event the sequential number and magnitude are also specified. Open stars indicate location of events with M > 3.0, while gray squares represent all the other earthquakes. The sequence spans a time interval of about one month and covers an area of about 60 km × 30 km. The figure was generated by using the Generic Mapping Tools (http://gmt.soest.hawaii.edu/)35. The topography is based on the ETOPO1 1 Arc-Minute Global Relief Model, http://www.ngdc.noaa.gov/mgg/global/global.html36.

Mentions: The Emilia region, Northern Apennines, Italy, was struck by a seismic sequence that started on May 19, 2012, at 23:13:27 GMT with a Mw 3.8 earthquake. It produced about 2100 events during the following month, affecting an area of about 60 km × 30 km elongated in the EW direction (Figure 1). The sequence began with the reactivation of two buried, sub-parallel N100°E-striking thrust faults with hypocenters located mainly in the upper 10 km1. The largest events, Mw 5.6 and 5.4, occurred on May, 20 and 29, respectively, and were followed by 6 Mw > 4.5 earthquakes over the next 2 weeks.


Combining stress transfer and source directivity: the case of the 2012 Emilia seismic sequence.

Convertito V, Catalli F, Emolo A - Sci Rep (2013)

Location map of the 2012 Emilia earthquake sequence.Geographic location of the 2012 Emilia seismic sequence (Italian Seismological Instrumental and parametric Data-basE, http://iside.rm.ingv.it). Orange dots, with corresponding focal mechanisms3, represent the epicenters of the main events analysed in this study and listed in Table 1. Red dots represent the location of events 2 and 7, whose focal mechanisms have been estimated by average of the known focal mechanisms. For each event the sequential number and magnitude are also specified. Open stars indicate location of events with M > 3.0, while gray squares represent all the other earthquakes. The sequence spans a time interval of about one month and covers an area of about 60 km × 30 km. The figure was generated by using the Generic Mapping Tools (http://gmt.soest.hawaii.edu/)35. The topography is based on the ETOPO1 1 Arc-Minute Global Relief Model, http://www.ngdc.noaa.gov/mgg/global/global.html36.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3814900&req=5

f1: Location map of the 2012 Emilia earthquake sequence.Geographic location of the 2012 Emilia seismic sequence (Italian Seismological Instrumental and parametric Data-basE, http://iside.rm.ingv.it). Orange dots, with corresponding focal mechanisms3, represent the epicenters of the main events analysed in this study and listed in Table 1. Red dots represent the location of events 2 and 7, whose focal mechanisms have been estimated by average of the known focal mechanisms. For each event the sequential number and magnitude are also specified. Open stars indicate location of events with M > 3.0, while gray squares represent all the other earthquakes. The sequence spans a time interval of about one month and covers an area of about 60 km × 30 km. The figure was generated by using the Generic Mapping Tools (http://gmt.soest.hawaii.edu/)35. The topography is based on the ETOPO1 1 Arc-Minute Global Relief Model, http://www.ngdc.noaa.gov/mgg/global/global.html36.
Mentions: The Emilia region, Northern Apennines, Italy, was struck by a seismic sequence that started on May 19, 2012, at 23:13:27 GMT with a Mw 3.8 earthquake. It produced about 2100 events during the following month, affecting an area of about 60 km × 30 km elongated in the EW direction (Figure 1). The sequence began with the reactivation of two buried, sub-parallel N100°E-striking thrust faults with hypocenters located mainly in the upper 10 km1. The largest events, Mw 5.6 and 5.4, occurred on May, 20 and 29, respectively, and were followed by 6 Mw > 4.5 earthquakes over the next 2 weeks.

Bottom Line: We find that static stress redistribution alone is not capable of explaining the locations of subsequent events.We conclude that dynamic triggering played a significant role in driving the sequence.This triggering was also associated with a variation in permeability and a pore pressure increase in an area characterized by a massive presence of fluids.

View Article: PubMed Central - PubMed

Affiliation: Istituto Nazionale di Geofisica e Vulcanologia - Osservatorio Vesuviano, Via Diocleziano 328, 80124, Napoli, Italy.

ABSTRACT
The Emilia seismic sequence (Northern Italy) started on May 2012 and caused 17 casualties, severe damage to dwellings and forced the closure of several factories. The total number of events recorded in one month was about 2100, with local magnitude ranging between 1.0 and 5.9. We investigate potential mechanisms (static and dynamic triggering) that may describe the evolution of the sequence. We consider rupture directivity in the dynamic strain field and observe that, for each main earthquake, its aftershocks and the subsequent large event occurred in an area characterized by higher dynamic strains and corresponding to the dominant rupture direction. We find that static stress redistribution alone is not capable of explaining the locations of subsequent events. We conclude that dynamic triggering played a significant role in driving the sequence. This triggering was also associated with a variation in permeability and a pore pressure increase in an area characterized by a massive presence of fluids.

No MeSH data available.


Related in: MedlinePlus