ISC-GEM: Global Instrumental Earthquake Catalogue (1900–2009), III. Re-computed M and m, proxy M, final magnitude composition and completeness assessment

Giacomo, Domenico Di; Bondár, István; Storchak, Dmitry A.; Engdahl, E. R.; Bormann, Peter; Harris, James M.

doi:10.1016/j.pepi.2014.06.005

Cited by 144 publications

(80 citation statements)

References 29 publications

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“…For events with moments not listed by other sources, we use M w or M e , and when neither of them was given, we determine M w from M s by calculating the static seismic moment via the relations of Di Giacomo et al (2015).…”

Section: Data Preparationmentioning

confidence: 99%

Testing stress shadowing effects at the South American subduction zone

Roth¹,

Dahm²,

Hainzl³

2017

Geophysical Journal International

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S U M M A R YThe seismic gap hypothesis assumes that a characteristic earthquake is followed by a long period with a reduced occurrence probability for the next large event on the same fault segment, as a consequence of the induced stress shadow. The gap model is commonly accepted by geologists and is often used for time-dependent seismic hazard estimations. However, systematic and rigorous tests to verify the seismic gap model have often failed so far, which might be partially related to limited data and too tight model assumptions. In this study, we relax the assumption of a characteristic size and location of repeating earthquakes and analyse one of the best available data sets, namely the historical record of major earthquakes along a 3000 km long linear segment of the South American subduction zone. To test whether a stress shadow effect is observable, we compiled a comprehensive catalogue of mega-thrust earthquakes along this plate boundary from 1520 to 2015 containing 174 earthquakes with M w > 6.5. In our new testing approach, we analyse the time span between an earthquake and the last event that ruptured the epicentre location, where we consider the impact of the uncertainties of epicentres and rupture extensions. Assuming uniform boundary conditions along the trench, we compare the distribution of these recurrence times with simple recurrence models. We find that the distribution is in all cases almost exponentially distributed corresponding to a random (Poissonian) process; despite some tendencies for clustering of the M w ≥ 7 events and a weak quasi-periodicity of the M w ≥ 8 earthquakes, respectively. To verify whether the absence of a clear stress shadow signal is related to physical assumptions or data uncertainties, we perform simulations of a physics-based stochastic earthquake model considering rate and state-dependent earthquake nucleation, which are adapted to the observations with regard to the number of events, spatial extend, size distribution and involved uncertainties. Our simulations show that the catalogue uncertainties lead to a significant blurring of the theoretically peaked distribution, but the distribution would be still distinguishable from the observed one for M w ≥ 7 events. However, considering the stress transfer to adjacent fault segments and heterogeneous instead of constant stress drop within the rupture zone can explain the observed recurrence time distribution. We conclude that simplified recurrence models, ignoring the complexity of the underlying physical process, cannot be applied for forecasting the M w ≥ 7 earthquake occurrence at this plate boundary.

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Section: Data Preparationmentioning

confidence: 99%

Testing stress shadowing effects at the South American subduction zone

Roth¹,

Dahm²,

Hainzl³

2017

Geophysical Journal International

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“…(2) and Eq. (3) developed by [11] successfully converted the surface and body wave magnitude available in the country into moment magnitude so that it can be used in this equation.…”

Section: =mentioning

confidence: 99%

Development of a Probabilistic Liquefaction Potential Map for Metro Manila

2016

geomate

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ABSTRACT:The study aimed to create a probabilistic liquefaction potential map for Metro Manila to help prepare for future calamities. A liquefaction opportunity map was produced by computing the probability of an earthquake with a moment magnitude of at least 5.2 from occurring. Historical data were gathered from 7 surrounding active faults within a 150 km radius of Metro Manila to determine their recurrence. A liquefaction susceptibility map was also developed by taking into consideration the conditions of the soil. Approximately 1000+ borehole logs scattered across Metro Manila was used in developing this map. These two maps were then combined to create the probabilistic liquefaction potential map. The results show that there is only a 2% chance of an earthquake capable of triggering a liquefaction occurring in a given year but in 50 years, there is a 10% chance of exceedance coming from an earthquake with an acceleration of 0.7g. The earthquake is most likely to come from the Valley Fault System which runs straight through Metro Manila.

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“…As such, our quantitative understanding of the Earth's seismicity during those decades remains approximate. Particularly worrisome in this respect and as detailed by Lee and Engdahl [40], is the trend consisting of expressing conventional magnitudes (M s ; m b , or ''Pasadena'' magnitudes M PAS compiled in the 1940s and 1950s by Gutenberg and Richter [26]) as ''moment magnitudes'', the so-called ''proxy-M w '' [16], based on scaling laws that the relevant earthquake may or may not have followed. In principle, the use of the symbol M w should certify that it represents the interpretation, in terms of a magnitude, of a bonafide seismic moment computation, as originally defined in Kanamori's [35] ''charter'' paper on the moment magnitude M w .…”

Section: Golitsyn Ew 24 April 1916mentioning

confidence: 99%

Historical seismograms: Preserving an endangered species

Okal

2015

GeoResJ

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a b s t r a c tThe youth of seismology as a science, compared to the typical duration of seismic cycles, results in a relative scarcity of records of large earthquakes available for processing by modern analytical techniques, which in turn makes archived datasets of historical seismograms extremely valuable in order to enhance our understanding of the occurrence of large, destructive earthquakes. Unfortunately, the value of these datasets is not always perceived adequately by decision-making administrators, which has resulted in the destruction (or last-minute salvage) of irreplaceable datasets.We present a quick review of the nature of the datasets of seismological archives, and of specific algorithms allowing their use for the modern retrieval of the source characteristics of the relevant earthquakes. We then describe protocols for the transfer of analog datasets to digital support, including by contact-less photography when the poor physical state of the records prevents the use of mechanical scanners.Finally, we give some worldwide examples of existing collections, and of successful programs of digital archiving of these valuable datasets.

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ISC-GEM: Global Instrumental Earthquake Catalogue (1900–2009), III. Re-computed M and m, proxy M, final magnitude composition and completeness assessment

Cited by 144 publications

References 29 publications

Testing stress shadowing effects at the South American subduction zone

Testing stress shadowing effects at the South American subduction zone

Development of a Probabilistic Liquefaction Potential Map for Metro Manila

Historical seismograms: Preserving an endangered species

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