Assessing the Quality of Earthquake Catalogues: Estimating the Magnitude of Completeness and Its Uncertainty

Woessner, J.

doi:10.1785/0120040007

Cited by 923 publications

(717 citation statements)

References 53 publications

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“…44 Earthquake catalogues are known to be incomplete towards small magnitudes, in particular directly after large earthquakes 45 . To avoid effects of incomplete detections, we used a cutoff magnitude of M c =3 which is -to be conservative -well above the completeness value of 2.6 estimated by the maximum curvature method inside the box 46 …”

Section: Earthquake Catalogue Production and Analysismentioning

confidence: 99%

Gradual unlocking of plate boundary controlled initiation of the 2014 Iquique earthquake

Schurr

Asch

Hainzl

et al. 2014

Nature

317

364

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Several major earthquakes (Mw>7) have occurred in this gap since 1850 (Fig. 1); the largest until now was the Mw 7.7 Tocopilla earthquake in 2007, which broke the southern rim of this segment beneath and north of Mejillones Peninsula along a total length of 150 km. Only the downdip end of the locked zone slipped in this event, and the total slip in the rupture area was less than 2.6 m 6,7 leaving most of the past slip deficit of c. 8-9 m accumulated since 1877 3 approaches. First, we performed waveform modelling of local strong motion seismograms and teleseismic body waves to constrain the kinematic development of the rupture towards the final displacement in a joint inversion with continuous GPS data of static displacements (Fig. 1, 2a). Second, we use the backprojection technique applied to stations in North America to map the radiation of high frequency seismic waves (HFSR; 1-4 Hz) 9,10 . The latter technique is not sensitive to absolute slip amplitudes, but rather to changes in slip and rupture velocity.During the first 35-40s the rupture propagated downdip with increasing velocity, nearly reaching the coastline (Fig. 2a,b). Surprisingly, towards the end of the rupture, the area near the epicenter was reactivated. In spite of the relatively complicated kinematic history of the rupture the cumulative slip shows a simple 'bull's eye' pattern with a peak coseismic slip of (Fig. 3a). The Iquique main shock nucleated at the 4 northwestern border of a locked patch and ruptured towards its center (Fig. 2a, 3a). The downdip end of the main shock as well as for the large Mw 7.6 aftershock rupture mapped both by the HFSR and co-seismic slip agrees quite accurately with the downdip end interseismic coupling (Fig. 2a,c 3a). The accelerated downdip rupture propagation for both earthquakes closely followed the gradient towards higher locking. Therefore, the Iquique event and its largest aftershock appear to have broken the central, only partly locked segment of the Northern Chile Southern Peru seismic gap releasing part of the slip deficit accumulated here since 1877 (cf. Fig. 1).The seismicity before the Iquique earthquake also concentrates in this zone of intermediate locking at the fringe of the highly locked -high slip patch (Fig. 3a). Starting in July 2013, three foreshock clusters with increasingly larger peak magnitudes and cumulative seismic moment occurred here (Fig. 2c, 3a,c). The mainshock rupture started at the northern end of the foreshock zone, inside the region of intermediate locking (Fig. 2c, 3a). Interestingly, the second foreshock cluster (January 2014) is associated with a weak transient deformation, whereas the third cluster (March 2014) shows a very distinct transient signal. GPS displacement vectors calculated over the times spanning these foreshock clusters point towards the cluster epicentres (Extended Data Figure 4). Deformation for both transients is entirely explained by the cumulative coseismic displacement of the respective foreshock clusters (Fig. 3d inset, Extended Data Figure 4). The ar...

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Section: Earthquake Catalogue Production and Analysismentioning

confidence: 99%

Gradual unlocking of plate boundary controlled initiation of the 2014 Iquique earthquake

Schurr

Asch

Hainzl

et al. 2014

Nature

317

364

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“…This is the preferred aftershock discriminant when the Mc of the catalog in the region is a few magnitude units less than the mainshock. (Woessner and Wiemer, 2005). Future application to a number of other test sites will first require building seismicity catalogs with lower Mc values through correlation (e.g.…”

Section: Discussionmentioning

confidence: 99%

Aftershock Characteristics as a Means of Discriminating Explosions from Earthquakes

Ford¹,

Walter²

2010

Bulletin of the Seismological Society of America

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The behavior of aftershock sequences around the Nevada Test Site in the southern Great Basin is characterized as a potential discriminant between explosions and earthquakes. The aftershock model designed by Jones (1989, 1994) allows for a probabilistic statement of earthquake-like aftershock behavior at any time after the mainshock. We use this model to define two types of aftershock discriminants. The first defines M X , or the minimum magnitude of an aftershock expected within a given duration after the mainshock with probability X. Of the 67 earthquakes with M>4 in the study region, 63 of them produce an aftershock greater than M 99 within the first seven days after a mainshock. This is contrasted with only six of 93 explosions with M>4 that produce an aftershock greater than M 99 for the same period. If the aftershock magnitude threshold is lowered and the M 90 criteria is used, then no explosions produce an aftershock greater than M 90 for durations that end more than 17 days after the mainshock. The other discriminant defines N X , or the minimum cumulative number of aftershocks expected for given time after the mainshock with probability X. Similar to the aftershock magnitude discriminant, five earthquakes do not produce more aftershocks than N 99 within 7 days after the mainshock. However, within the same period all but one explosion produce less aftershocks then N 99 . One explosion is added if the duration is shortened to two days after than mainshock. The cumulative number aftershock discriminant is more reliable, especially at short durations, but requires a low magnitude of completeness for the given earthquake catalog. These results at NTS are quite promising and should be evaluated at other nuclear test sites to understand the effects of differences in the geologic setting and nuclear testing practices on its performance.

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“…One of the basic parameters to assess such quality is the magnitude of completeness (M c ), defined as the lowest magnitude for which all earthquakes can be detected in a space-time volume (e.g., Rydelek and Sacks, 1989;Woessner and Wiemer, 2005). Its reliable estimation is essential for the statistical analysis of seismicity and hazard-related studies, such as the analysis of rate changes, static and dynamic triggering, probabilistic seismic-hazard assessment, and earthquake forecasting.…”

Section: Introductionmentioning

confidence: 99%

“…Most methods are based on catalog data and define M c as the lowest magnitude at which the observed frequency-magnitude distribution (FMD) deviates from the assumed Gutenberg-Richter (GR) relation. These methods include the maximum curvature technique (Wyss et al, 1999;Wiemer and Wyss, 2000), entire magnitude range (Woessner and Wiemer, 2005), and goodness-of-fit test (Wiemer and Wyss, 2000). These techniques need to be applied for time intervals during which temporal variations of M c can be neglected.…”

Section: Introductionmentioning

confidence: 99%

Maximum Magnitude of Completeness in a Salt Mine

Maghsoudi¹,

Cesca²,

Hainzl³

et al. 2015

Bulletin of the Seismological Society of America

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In this study, we analyze acoustic emission (AE) data recorded at the Morsleben salt mine, Germany, to assess the catalog completeness, which plays an important role in any seismicity analysis. We introduce the new concept of a magnitude completeness interval consisting of a maximum magnitude of completeness (M cmax ) in addition to the well-known minimum magnitude of completeness. This is required to describe the completeness of the catalog, both for the smallest events (for which the detection performance may be low) and for the largest ones (which may be missed because of sensors saturation). We suggest a method to compute the maximum magnitude of completeness and calculate it for a spatial grid based on (1) the prior estimation of saturation magnitude at each sensor, (2) the correction of the detection probability function at each sensor, including a drop in the detection performance when it saturates, and (3) the combination of detection probabilities of all sensors to obtain the network detection performance. The method is tested using about 130,000 AE events recorded in a period of five weeks, with sources confined within a small depth interval, and an example of the spatial distribution of M cmax is derived. The comparison between the spatial distribution of M cmax and of the maximum possible magnitude (M max ), which is here derived using a recently introduced Bayesian approach, indicates that M max exceeds M cmax in some parts of the mine. This suggests that some large and important events may be missed in the catalog, which could lead to a bias in the hazard evaluation.

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Assessing the Quality of Earthquake Catalogues: Estimating the Magnitude of Completeness and Its Uncertainty

Cited by 923 publications

References 53 publications

Gradual unlocking of plate boundary controlled initiation of the 2014 Iquique earthquake

Gradual unlocking of plate boundary controlled initiation of the 2014 Iquique earthquake

Aftershock Characteristics as a Means of Discriminating Explosions from Earthquakes

Maximum Magnitude of Completeness in a Salt Mine

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