A probabilistic approach for the classification of earthquakes as ‘triggered’ or ‘not triggered’

Passarelli, Luigi; Maccaferri, Francesco; Rivalta, Eleonora; Dahm, Torsten; Boku, E.

doi:10.1007/s10950-012-9289-4

Cited by 28 publications

(18 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4), leads to an increase of triggering probability. The magnitude of the increase of probability scales with the intensity of the Coulomb stress and decreases in time according to the decay rate of aftershocks (Dieterich 1994;Passarelli et al 2013). However, the possibility that a major tectonic event is triggered is mainly controlled by the tectonically pre-loaded stresses (Cesca et al 2013a;Passarelli et al 2013), so that the possibility that an earthquake on the Castrovillari fault is triggered due static stress interaction with seismic events in the Mercure basin cannot be excluded.…”

Section: Focal Mechanisms and Coulomb Stress Transfermentioning

confidence: 99%

Aseismic transient driving the swarm-like seismic sequence in the Pollino range, Southern Italy

Passarelli¹,

Hainzl²,

Cesca³

et al. 2015

Geophysical Journal International

Self Cite

View full text Add to dashboard Cite

S U M M A R YTectonic earthquake swarms challenge our understanding of earthquake processes since it is difficult to link observations to the underlying physical mechanisms and to assess the hazard they pose. Transient forcing is thought to initiate and drive the spatio-temporal release of energy during swarms. The nature of the transient forcing may vary across sequences and range from aseismic creeping or transient slip to diffusion of pore pressure pulses to fluid redistribution and migration within the seismogenic crust. Distinguishing between such forcing mechanisms may be critical to reduce epistemic uncertainties in the assessment of hazard due to seismic swarms, because it can provide information on the frequency-magnitude distribution of the earthquakes (often deviating from the assumed Gutenberg-Richter relation) and on the expected source parameters influencing the ground motion (for example the stress drop). Here we study the ongoing Pollino range (Southern Italy) seismic swarm, a long-lasting seismic sequence with more than five thousand events recorded and located since October 2010. The two largest shocks (magnitude M w = 4.2 and M w = 5.1) are among the largest earthquakes ever recorded in an area which represents a seismic gap in the Italian historical earthquake catalogue. We investigate the geometrical, mechanical and statistical characteristics of the largest earthquakes and of the entire swarm. We calculate the focal mechanisms of the M l > 3 events in the sequence and the transfer of Coulomb stress on nearby known faults and analyse the statistics of the earthquake catalogue. We find that only 25 per cent of the earthquakes in the sequence can be explained as aftershocks, and the remaining 75 per cent may be attributed to a transient forcing. The b-values change in time throughout the sequence, with low b-values correlated with the period of highest rate of activity and with the occurrence of the largest shock. In the light of recent studies on the palaeoseismic and historical activity in the Pollino area, we identify two scenarios consistent with the observations and our analysis: This and past seismic swarms may have been 'passive' features, with small fault patches failing on largely locked faults, or may have been accompanied by an 'active', largely aseismic, release of a large portion of the accumulated tectonic strain. Those scenarios have very different implications for the seismic hazard of the area.

show abstract

Section: Focal Mechanisms and Coulomb Stress Transfermentioning

confidence: 99%

Aseismic transient driving the swarm-like seismic sequence in the Pollino range, Southern Italy

Passarelli¹,

Hainzl²,

Cesca³

et al. 2015

Geophysical Journal International

Self Cite

View full text Add to dashboard Cite

show abstract

“…On day 4.8 from the onset of the seismic swarm, a M l =6.5 event occurred near the propagating tip (Figure ). (see other examples of large dike‐triggered earthquakes by Buck et al [] and Passarelli et al []). After that, the dike stopped propagating and continued inflating and possibly extending vertically, as demonstrated by increased displacements at the GPS stations at Miyakejima, Kozushima, Niijima, and on the Japan mainland [ Ozawa et al , ; Nakada et al , ; Yamaoka et al , ; Hughes , ].…”

Section: Tectonic Setting and Chronology Of The Intrusionmentioning

confidence: 99%

Stress changes, focal mechanisms, and earthquake scaling laws for the 2000 dike at Miyakejima (Japan)

et al. 2015

Self Cite

View full text Add to dashboard Cite

Faulting processes in volcanic areas result from a complex interaction of pressurized fluid-filled cracks and conduits with the host rock and local and regional tectonic setting. Often, volcanic seismicity is difficult to decipher in terms of the physical processes involved, and there is a need for models relating the mechanics of volcanic sources to observations. Here we use focal mechanism data of the energetic swarm induced by the 2000 dike intrusion at Miyakejima (Izu Archipelago, Japan), to study the relation between the 3-D dike-induced stresses and the characteristics of the seismicity. We perform a clustering analysis on the focal mechanism (FM) solutions and relate them to the dike stress field and to the scaling relationships of the earthquakes. We find that the strike and rake angles of the FMs are strongly correlated and cluster on bands in a strike-rake plot. We suggest that this is consistent with optimally oriented faults according to the expected pattern of Coulomb stress changes. We calculate the frequency-size distribution of the clustered sets finding that focal mechanisms with a large strike-slip component are consistent with the Gutenberg-Richter relation with a b value of about 1. Conversely, events with large normal faulting components deviate from the Gutenberg-Richter distribution with a marked roll-off on its right-hand tail, suggesting a lack of large-magnitude events (M w > 5.5). This may result from the interplay of the limited thickness and lower rock strength of the layer of rock above the dike, where normal faulting is expected, and lower stress levels linked to the faulting style and low confining pressure.

show abstract

“…(1)- (3) are appropriate to calculate the seismicity rate in case of gradual changes of stress; e.g., as the effect of fluid injection in a reservoir . This is different from the original RaS type model concerning a sudden change in stress caused by a large earthquake (Catalli et al, 2008;Dieterich et al, 2000;Toda and Stein, 2003) or an instantaneous dyke intrusion as assumed by Passarelli et al (2013). In both cases, a seismicity dataset is required since the stress changes are calculated based on the focal mechanism of an earthquake.…”

Section: Time-dependent Rate-and-state Model and Link To The Geomechamentioning

confidence: 98%

“…A step towards a link between geomechanical numerical reservoir models and tectonic earthquakes is shown by Passarelli et al (2013). They present an approach for how to estimate the probability of whether a tectonic earthquake was triggered by a stress change of a dike intrusion or not.…”

Section: Introductionmentioning

confidence: 99%

Forward modelling of seismicity rate changes in georeservoirs with a hybrid geomechanical–statistical prototype model

et al. 2014

View full text Add to dashboard Cite

. (2014): Forward modelling of seismicity rate changes in georeservoirs with a hybrid geomechanical-statistical prototype model. 52, A key challenge for the development of Enhanced Geothermal Systems (EGS) is to forecast the probability of occurrence of seismic events that have the potential to damage manmade structures. Induced seismicity results from man-made time-dependent stress changes, e.g., due to fluid injection, shut-in and fluid or steam production. To accomplish a classical Probabilistic Seismic Hazard Assessment (PSHA) a catalogue of induced seismicity is required. In addition, PSHA does not return any practical recommendation for how to treat the reservoir geomechanically in order to lower the probability of occurrence of induced seismicity. Thus, we propose to link the simulated stress changes from forward geomechanical numerical reservoir models with the statistical rate-and-state approach of Dieterich (1994). Using this link we translate the modelled time-dependent stress changes into time-dependent changes of seismicity rates. This approach is general and independent of the incorporated geomechanical numerical model used. We exemplify our hybrid model approach using a geomechanical model that describes the stimulation of the well GPK4 at the EGS site in Soultz-sous-Forêts (France) including the shut-in phase. By changing the injection rate in the geomechanical model we generate various synthetic injection scenarios. With these scenarios we can study the effect on the seismicity rate and provide a recommendation for which injection experiment results in the least increase of seismicity rate. The results indicate an explicit coupling between the time-depending stress changes and the induced seismicity rate for each scenario. Even though the hybrid model cannot be used in general to derive absolute values of the rate of induced seismicity a priori (this is only possible if the geomechanical model can be calibrated against observed induced events), it serves as a tool to test the effect of stress changes on the induced seismicity rate. The approach described here is a prototype model illustrating the general workflow. In particular the geomechanical model can be replaced by any other type of reservoir description.

show abstract

A probabilistic approach for the classification of earthquakes as ‘triggered’ or ‘not triggered’

Cited by 28 publications

References 40 publications

Aseismic transient driving the swarm-like seismic sequence in the Pollino range, Southern Italy

Aseismic transient driving the swarm-like seismic sequence in the Pollino range, Southern Italy

Stress changes, focal mechanisms, and earthquake scaling laws for the 2000 dike at Miyakejima (Japan)

Forward modelling of seismicity rate changes in georeservoirs with a hybrid geomechanical–statistical prototype model

Contact Info

Product

Resources

About