Waveform Relocated Earthquake Catalog for Southern California (1981 to June 2011)

Hauksson, Egill; Yang, Wein-Duo; Shearer, Peter M.

doi:10.1785/0120120010

Cited by 405 publications

(561 citation statements)

References 14 publications

Supporting

Mentioning

534

Contrasting

Unclassified

Order By: Relevance

“…the high-resolution southern California catalog (see Data and Resources) containing earthquakes from 1981 to 2011 that occurred in the region extending from Baja California in the south to Coalinga and the Owens Valley in the north (Hauksson et al, 2012), with a cutoff magnitude of M c 0 2:0 (which ensures generally complete recordings leading to 111,980 earthquakes above this threshold); and 2. the combined catalog of the four last large earthquake swarms that occurred in 2000, 2008, 2011, and 2014 in western Bohemia (see Data and Resources), with a cutoff magnitude of 0.5, leading to 11,650 events.…”

Section: Applications Rate-dependent Apparent B-value Decreasementioning

confidence: 99%

Rate‐Dependent Incompleteness of Earthquake Catalogs

Hainzl

2016

Seismological Research Letters

122

114

View full text Add to dashboard Cite

Important information about the earthquake generation process can be gained from instrumental earthquake catalogs, but this requires complete recordings to avoid biased results. The local completeness magnitude M c is known to depend on general conditions such as the seismographic network and the environmental noise, which generally limit the possibility of detecting small events. The detectability can be additionally reduced by an earthquake-induced increase of the noise level leading to shortterm variations of M c , which cannot be resolved by traditional methods relying on the analysis of the frequency-magnitude distribution. Based on simple assumptions, I propose a new method to estimate such temporal excursions of M c solely based on the estimation of the earthquake rate resulting in a high temporal resolution of M c . The approach is shown to be in agreement with the apparent decrease of the estimated Gutenberg-Richter b-value in high-activity phases of recorded data sets and the observed incompleteness periods after mainshocks. Furthermore, an algorithm to estimate temporal changes of M c is introduced and applied to empirical aftershock and swarm sequences from California and central Europe, indicating that observed b-value fluctuations are often related to rate-dependent incompleteness of the earthquake catalogs.Online Material: MATLAB code to compute rate-dependent completeness magnitude, and figures showing variation in the estimated M c values in equalized time scale.

show abstract

Section: Applications Rate-dependent Apparent B-value Decreasementioning

confidence: 99%

Rate‐Dependent Incompleteness of Earthquake Catalogs

Hainzl

2016

Seismological Research Letters

122

114

View full text Add to dashboard Cite

show abstract

“…We use the relocated high-resolution Southern California catalogue containing earthquakes from 1981 to 2011 in the region extending from Baja California in the south to Coalinga and Owens Valley in the north (Hauksson et al 2012). This area is roughly rectangular ranging from 30 • to 37.5 • latitude and from −113 • to −122 • longitude.…”

Section: Observational Datamentioning

confidence: 99%

Statistical estimation of the duration of aftershock sequences

Hainzl¹,

Christophersen

Rhoades

et al. 2016

Geophys. J. Int.

View full text Add to dashboard Cite

S U M M A R YIt is well known that large earthquakes generally trigger aftershock sequences. However, the duration of those sequences is unclear due to the gradual power-law decay with time. The triggering time is assumed to be infinite in the epidemic type aftershock sequence (ETAS) model, a widely used statistical model to describe clustering phenomena in observed earthquake catalogues. This assumption leads to the constraint that the power-law exponent p of the Omori-Utsu decay has to be larger than one to avoid supercritical conditions with accelerating seismic activity on long timescales. In contrast, seismicity models based on rate-and statedependent friction observed in laboratory experiments predict p ≤ 1 and a finite triggering time scaling inversely to the tectonic stressing rate. To investigate this conflict, we analyse an ETAS model with finite triggering times, which allow smaller values of p. We use synthetic earthquake sequences to show that the assumption of infinite triggering times can lead to a significant bias in the maximum likelihood estimates of the ETAS parameters. Furthermore, it is shown that the triggering time can be reasonably estimated using real earthquake catalogue data, although the uncertainties are large. The analysis of real earthquake catalogues indicates mainly finite triggering times in the order of 100 days to 10 years with a weak negative correlation to the background rate, in agreement with expectations of the rate-and state-friction model. The triggering time is not the same as the apparent duration, which is the time period in which aftershocks dominate the seismicity. The apparent duration is shown to be strongly dependent on the mainshock magnitude and the level of background activity. It can be much shorter than the triggering time. Finally, we perform forward simulations to estimate the effective forecasting period, which is the time period following a mainshock, in which ETAS simulations can improve rate estimates after the occurrence of a mainshock. We find that this effective forecasting period is only in the order of 100 days for moderate mainshocks and in the order of a few years for large events, even if the underlying triggering process lasts much longer.

show abstract

“…The 230-km-long San Jacinto fault zone (SJFZ) is the most seismically active fault zone in southern California (Hauksson et al 2012) and accommodates a large portion of the plate boundary motion in the region (Johnson et al1994;Fialko 2006;Lindsey et al 2014). Extensive palaeoseismic work indicates that the SJFZ has repeatedly produced large (M W > 7.0) earthquakes in the past 4000 yr (Rockwell et al 2015, and references therein).…”

Section: Introductionmentioning

confidence: 99%

“…Variations of lithological units and geometrical complexities (e.g. Sharp 1967) produce non-uniform distribution of strain and seismicity along the length of the fault (Sanders & Kanamori 1984;Sanders & Magistrale 1997, Hauksson et al 2012. Recent tomographic studies (Allam & Ben-Zion 2012; Allam et al 2014a; Zigone et al 2015) imaged with nominal resolution of 1-2 km large-scale variations of seismic velocities across the fault and significant damage zones at different locations.…”

Section: Introductionmentioning

confidence: 99%

Internal structure of the San Jacinto fault zone at Blackburn Saddle from seismic data of a linear array

Ben‐Zion

Ross

et al. 2017

Geophysical Journal International

View full text Add to dashboard Cite

S U M M A R YLocal and teleseismic earthquake waveforms recorded by a 180-m-long linear array (BB) with seven seismometers crossing the Clark fault of the San Jacinto fault zone northwest of Anza are used to image a deep bimaterial interface and core damage structure of the fault. Delay times of P waves across the array indicate an increase in slowness from the southwest most (BB01) to the northeast most (BB07) station. Automatic algorithms combined with visual inspection and additional analyses are used to identify local events generating fault zone head and trapped waves. The observed fault zone head waves imply that the Clark fault in the area is a sharp bimaterial interface, with lower seismic velocity on the southwest side. The moveout between the head and direct P arrivals for events within ∼40 km epicentral distance indicates an average velocity contrast across the fault over that section and the top 20 km of 3.2 per cent. A constant moveout for events beyond ∼40 km to the southeast is due to off-fault locations of these events or because the imaged deep bimaterial interface is discontinuous or ends at that distance. The lack of head waves from events beyond ∼20 km to the northwest is associated with structural complexity near the Hemet stepover. Events located in a broad region generate fault zone trapped waves at stations BB04-BB07. Waveform inversions indicate that the most likely parameters of the trapping structure are width of ∼200 m, S velocity reduction of 30-40 per cent with respect to the bounding blocks, Q value of 10-20 and depth of ∼3.5 km. The trapping structure and zone with largest slowness are on the northeast side of the fault. The observed sense of velocity contrast and asymmetric damage across the fault suggest preferred rupture direction of earthquakes to the northwest. This inference is consistent with results of other geological and seismological studies.

show abstract

Waveform Relocated Earthquake Catalog for Southern California (1981 to June 2011)

Cited by 405 publications

References 14 publications

Rate‐Dependent Incompleteness of Earthquake Catalogs

Rate‐Dependent Incompleteness of Earthquake Catalogs

Statistical estimation of the duration of aftershock sequences

Internal structure of the San Jacinto fault zone at Blackburn Saddle from seismic data of a linear array

Contact Info

Product

Resources

About