Extension of the energy-to-moment parameter Θ to intermediate and deep earthquakes

Saloor, Nooshin; Okal, Emile A.

doi:10.1016/j.pepi.2017.10.006

Cited by 14 publications

(11 citation statements)

References 45 publications

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“…A peculiar rupture characteristic was also recorded from the 2016 event. Figure 10 shows radiated seismic energy versus seismic moment (Saloor & Okal, 2018) for a large worldwide data set of intermediate‐depth events (80–135 km). It essentially contrasts the energy ( E E ) estimated from P waves at high frequencies (0.5–10 s) and the moment ( M 0 ) measured at much longer periods (50–200 s).…”

Section: Discussionmentioning

confidence: 99%

“…By contrast, some “snappy” earthquakes have a blue‐shifted source spectrum and result in exceptional accelerations, and hence destruction. Saloor and Okal (2018) found that intermediate and especially deep earthquakes are much more linearly dependent in terms of their distribution of Θ, with only one clear outlier in their entire data set of close to 600 intermediate and deep earthquakes. Their conclusions are fully upheld in a recent update of their data set, now consisting of 917 intermediate and deep earthquakes up to and including March 2023 (Okal & Saloor, 2023).…”

Section: Discussionmentioning

confidence: 99%

“…There are two campaign GPS stations, BUK1 (Buka airport) and ARO2 (Aropa airport), where the model predicts 7.1 and 6.4 cm uplift, respectively. The small bull's eye symbol is the epicenter of the earthquake of 09 September 2005 identified as the only slow outlier in Saloor and Okal's (2018) data set. (b) GPS measurements of VLM from BUK1 and ARO2 present uplift of 12–15 cm by the 2016/2017 earthquakes, depending on possible pre‐existing postseismic VLM (a yellow line) after the November 2000 earthquakes occurred near the New Britain Island.…”

Section: Implications For Vertical Land Motion and Relative Sea Level...mentioning

confidence: 99%

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GRACE and GRACE Follow‐On Gravity Observations of Intermediate‐Depth Earthquakes Contrasted With Those of Shallow Events

Han,

Sauber,

Broerse

et al. 2024

JGR Solid Earth

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Earthquakes involve mass redistribution within the solid Earth and the ocean, and as a result, perturb the Earth's gravitational field. For most of the shallow (<60 km) earthquakes with Mw > 8.0, the GRACE satellite gravity measurements suggest considerable volumetric disturbance of rocks. At a spatial scale of hundreds of km, the effect of volumetric change exceeds gravity change by vertical deformation; for example, negative gravity anomalies associated with volumetric expansion are characteristic patterns after shallow thrust events. In this study, however, we report contrasting observations of gravity change from two intermediate‐depth (100–150 km) earthquakes of 2016 & 2017 Mw 8.0 (two combined) Papua New Guinea thrust faulting events and 2019 Mw 8.0 Peru normal faulting and highlight the importance of compressibility in earthquake deformation. The combined 2016/17 thrust events resulted in a positive gravity anomaly of 5–6 microGal around the epicenter, while the 2019 normal faulting produced a negative gravity anomaly of 3–4 microGal. Our modeling found that these gravity changes are manifestation of vertical deformation with limited volumetric change, distinct from gravity changes after the shallow earthquakes. The stronger resistance of rocks to volume change at intermediate‐depth results in largely incompressible deformation and thus in a gravity change dominated by vertical deformation. In addition, malleable rocks under high pressure and temperature at depth facilitated substantial afterslip and/or fast viscoelastic relaxation causing additional vertical deformation and gravity change equivalent to the coseismic change. For the Papua New Guinea events, this means that postseismic relaxation enhanced coseismic uplift and relative sea level decrease.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Implications For Vertical Land Motion and Relative Sea Level...mentioning

confidence: 99%

See 1 more Smart Citation

GRACE and GRACE Follow‐On Gravity Observations of Intermediate‐Depth Earthquakes Contrasted With Those of Shallow Events

Han,

Sauber,

Broerse

et al. 2024

JGR Solid Earth

View full text Add to dashboard Cite

show abstract

“…Note that the proposed approach is in principle suitable for including a larger variability of all the seismic parameters, certainly including rupture size and slip distributions. Moreover, our model considers only the endmember case of depth-dependent rigidity and uniform stress drop, whereas a more realistic model explaining observed earthquake durations should also include a variable stress drop with depth (Bilek and Lay 1999;Saloor and Okal 2018). In fact, the rigidity values implied by the constant stress drop endmember case are too low to explain some tsunami observations (Geist and Bilek 2001).…”

Section: Discussionmentioning

confidence: 99%

Effect of Shallow Slip Amplification Uncertainty on Probabilistic Tsunami Hazard Analysis in Subduction Zones: Use of Long-Term Balanced Stochastic Slip Models

Scala

Lorito

Romano

et al. 2019

Pure Appl. Geophys.

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The complexity of coseismic slip distributions influences the tsunami hazard posed by local and, to a certain extent, distant tsunami sources. Large slip concentrated in shallow patches was observed in recent tsunamigenic earthquakes, possibly due to dynamic amplification near the free surface, variable frictional conditions or other factors. We propose a method for incorporating enhanced shallow slip for subduction earthquakes while preventing systematic slip excess at shallow depths over one or more seismic cycles. The method uses the classic k-2 stochastic slip distributions, augmented by shallow slip amplification. It is necessary for deep events with lower slip to occur more often than shallow ones with amplified slip to balance the long-term cumulative slip. We evaluate the impact of this approach on tsunami hazard in the central and eastern Mediterranean Sea adopting a realistic 3D geometry for three subduction zones, by using it to model * 150,000 earthquakes with M w from 6.0 to 9.0. We combine earthquake rates, depth-dependent slip distributions, tsunami modeling, and epistemic uncertainty through an ensemble modeling technique. We found that the mean hazard curves obtained with our method show enhanced probabilities for larger inundation heights as compared to the curves derived from depthindependent slip distributions. Our approach is completely general and can be applied to any subduction zone in the world.

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“…The mainshock epicenter was located on the oceanic side of the Kuril-Kamchatka Trench about 100 km to the east of the epicenter of the 15 November 2006 earthquake, within the oceanic lithospheric plate. According to the earthquake's slowness classification, which depends on the energyto-moment ratio (Saloor & Okal, 2018), the 2006 earthquake was a slow event, or so-called ''tsunami earthquake''. In contrast, the 1994 event was a fast event, and the 2007 earthquake a regular event.…”

Section: Methodsmentioning

confidence: 99%

Tsunami Generation Efficiency of the 1994, 2006 and 2007 Kuril Islands Earthquakes

Kulikov

Ivanova

2021

Pure Appl. Geophys.

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generated trans-oceanic tsunamis that were recorded over the entire Pacific Ocean. The tsunami sources had significantly different geometries, which led to different impacts in the near-field and far-field zones. We used numerical models to investigate the source efficiency and resulting wave directivity of the three tsunamis. The tsunami models were validated and calibrated using field survey data from the Central Kuril Islands and deep-ocean bottom pressure records in the North Pacific. Using the full energy flux distribution, we conclude that the source of the 2007 event had the most well-defined energy flux directivity and that the tsunami energy radiation from the 1994 event was the most isotropic. Radiation patterns of each source clearly show the fraction of wave energy radiated into the open ocean, as well as that which penetrated into the Sea of Okhotsk through the Kuril Straits or was captured by the shelf and spread from the source area along the Kuril Ridge. We find a noticeable increase in the period of the leading wave emitted from the end of the elongated tsunami sources compared to the period of the waves formed in the transverse direction. The onshore-directed energy flux is shown to be a key factor controlling tsunami amplitudes at the coast.

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Extension of the energy-to-moment parameter Θ to intermediate and deep earthquakes

Cited by 14 publications

References 45 publications

GRACE and GRACE Follow‐On Gravity Observations of Intermediate‐Depth Earthquakes Contrasted With Those of Shallow Events

GRACE and GRACE Follow‐On Gravity Observations of Intermediate‐Depth Earthquakes Contrasted With Those of Shallow Events

Effect of Shallow Slip Amplification Uncertainty on Probabilistic Tsunami Hazard Analysis in Subduction Zones: Use of Long-Term Balanced Stochastic Slip Models

Tsunami Generation Efficiency of the 1994, 2006 and 2007 Kuril Islands Earthquakes

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