The role of afterslip in driving aftershock sequences

2020 ◽  
Author(s):  
Robert Churchill ◽  
Maximilian Werner ◽  
Juliet Biggs ◽  
Ake Fagereng
Keyword(s):  
Empirical Relationship ◽  
Individual Case ◽  
Aftershock Sequence ◽  
Sequence Evolution ◽  
Coulomb Stress Changes ◽  
Temporal Decay ◽  
Aftershock Sequences ◽  
Stress Changes ◽  
Tectonic Earthquakes ◽  
Spatio Temporal

<p>Aftershock sequences following large tectonic earthquakes exhibit considerable spatio-temporal complexity and suggest causative mechanisms beyond co-seismic, elasto-static Coulomb stress changes in the crust. Candidate mechanisms include dynamic triggering and postseismic processes such as viscoelastic relaxation, poroelastic rebound and aseismic afterslip, which has garnered particular interest recently. Aseismic afterslip – whereby localized frictional sliding within velocity-strengthening rheologies acts to redistribute lithospheric stresses in the postseismic phase – has been suggested by numerous studies to exert dominant control on aftershock sequence evolution, including productivity, spatial distribution and temporal decay.</p><p>As evidence is based overwhelmingly on individual case study analysis, we wish to systematically compare key metrics of aseismic afterslip and corresponding aftershock sequences to investigate this relationship. We specifically look for any empirical relationship between the seismic-equivalent moment of aseismic afterslip episodes and the corresponding aftershock sequence productivity. We first compile published afterslip models into a database containing moment estimates over varying time periods, as well as spatial distributions, temporal decays and modelling methodology as a supplementary resource. We then identify the corresponding aftershock sequence from the globally comparable USGS PDE catalog. As expected, coseismic moment exerts an obvious control on both afterslip moment and aftershock productivity – an effect we control for by normalising by mainshock moment and expected productivity (the Utsu-Seki law) respectively. Preliminary results suggest broad variability of both afterslip moment and aftershock productivity with no obvious control of afterslip on aftershocks beyond the scaling with mainshock size, including when separated by mainshock mechanism or region. As this study is insensitive to spatial and temporal distributions, we cannot rule out the potential influence afterslip exerts in these but find no evidence that afterslip drives overall productivity of aftershock sequences.</p>

A modified Coulomb failure seismicity model to study earthquake occurrence and frequency-magnitude distributions

2021 ◽  
Author(s):  
Torsten Dahm
Keyword(s):  
Tectonic Stress ◽  
Time Dependent ◽  
New Model ◽  
Coulomb Stress Changes ◽  
Stress Effects ◽  
Effective Media ◽  
Aftershock Sequences ◽  
Stress Changes ◽  
Coulomb Failure ◽  
Frequency Magnitude

<p>The linear Coulomb failure (LCM) and the rate-and-state model (RSM) are two widely-used physics-based seismicity models both assuming Coulomb stress changes acting on pre-existing populations of faults. While both predict background earthquake rates and time-dependent stress effects, only the RSM can additionally explain the time-dependent triggering of aftershocks.</p><p>We develop a modified effective media Coulomb model which accounts for the possibility of earthquake nucleation and retarded triggering of rupture. The new model has only two independent parameters and explains all statistical features of seismicity equally well as the RMS, but is simpler in its concept and provides insights in the possible nature of time-dependent frequency-magnitude distributions. Some of the statistical predictions are different compared to the RSM or LCM. For instance, the model domain is not limited to positive earthquake background or stressing rates; it can also simulate seismicity under zero stressing assumptions. The increase of background seismicity with tectonic stressing is nonlinear, different to the other models, and may even saturate if the tectonic stress loading is very strong. The Omori aftershock decay is predicted in the new model with an exponent of p=1 also for time periods much larger than the aftershock decay time, however, the productivity factor K is time dependent with a very slow exponential attenuation. The attenuation may explain the apparent variation of p in observed aftershock sequences. Interesting is also that the new model predicts a co-seismic peak of triggered aftershocks, which depends on the magnitude of the stress step and does not influence the attenuation of aftershocks following the stress step. It could be a physical explanation for the c-value in Omori’s law, the origin of which is still under discussion.</p><p>We compare the new model to RSM and LCM and discuss the possible implications for earthquake clustering and frequency magnitude distributions.</p>

Coseismic Slip Distribution of the 24 January 2020 Mw 6.7 Doganyol Earthquake and in Relation to the Foreshock and Aftershock Activities

2020 ◽  
Vol 92 (1) ◽  
pp. 127-139
Author(s):  
Xin Lin ◽  
Jinlai Hao ◽  
Dun Wang ◽  
Risheng Chu ◽  
Xiangfang Zeng ◽  
...  
Keyword(s):  
Seismic Risk ◽  
Body Wave ◽  
Surface Displacement ◽  
Coulomb Stress ◽  
Slip Model ◽  
Coseismic Slip ◽  
Coulomb Stress Changes ◽  
Aftershock Sequences ◽  
Stress Changes ◽  
And Migration

Abstract On 24 January 2020 (UTC), a destructive Mw 6.7 earthquake struck the east Anatolian fault of eastern Turkey after a series of foreshocks, causing many casualties and significant property damage. In this study, the rupture process of this earthquake is investigated with teleseismic broadband body-wave and surface-wave records. Results indicate that this earthquake is a left-lateral strike-slip event, and the rupture extends mainly to south. The main slip patch spreads ∼30  km along strike in the shallow above 14 km with a peak slip of ∼1.2  m, and the total seismic moment is 1.69×1019  N·m. The east–west component of horizontal surface displacement predicted with our slip model ranges from ∼0.4 to −0.3  m. The predicted displacements are consistent with the observed ones obtained from satellite images. We relocate 459 foreshocks and early aftershocks to explore the relationship between foreshock and aftershock sequences and coseismic slip. It is noted that there is an anticorrelation relationship between the distributions of early aftershocks and the coseismic slip. The strain energy in the large slip patch may have been sufficiently released by the mainshock; therefore, fewer early aftershocks occurred in that patch. Although we note a similar pattern between the relocated foreshock and coseismic slip, and a migration of foreshock, our dataset may not well resolve the correlation and migration due to the incomplete relocation foreshock catalog. Based on the slip model, we calculate the coulomb stress changes on the surrounding faults caused by the mainshock. The results reveal that the mainshock promoted stress accumulation on the northern and southern ends of the Elazig–Matalya segment and may reactivate the locked fault segment, leading to a high seismic risk in these regions. Although this earthquake does not significantly increase the coulomb stress change, the seismic risk of the Matalya–Kahraman Maras–Antakya segment should draw attention.

scholarly journals Transient postseismic mantle relaxation following 2004 Sumatra earthquake: implications of seismic vulnerability in the Andaman-Nicobar region

2012 ◽  
Vol 12 (2) ◽  
pp. 431-441
Author(s):  
C. D. Reddy ◽  
S. K. Prajapati ◽  
P. S. Sunil ◽  
S. K. Arora
Keyword(s):  
Seismic Vulnerability ◽  
Significant Risk ◽  
Stress Transfer ◽  
Earthquake Activity ◽  
Coulomb Stress Changes ◽  
2004 Sumatra Earthquake ◽  
Stress Changes ◽  
Near Shore ◽  
Spatio Temporal ◽  
Postseismic Relaxation

Abstract. Throughout the world, the tsunami generation potential of some large under-sea earthquakes significantly contributes to regional seismic hazard, which gives rise to significant risk in the near-shore provinces where human settlements are in sizeable population, often referred to as coastal seismic risk. In this context, we show from the pertinent GPS data that the transient stresses generated by the viscoelastic relaxation process taking place in the mantle is capable of rupturing major faults by stress transfer from the mantle through the lower crust including triggering additional rupture on the other major faults. We also infer that postseismic relaxation at relatively large depths can push some of the fault segments to reactivation causing failure sequences. As an illustration to these effects, we consider in detail the earthquake sequence comprising six events, starting from the main event of Mw = 7.5, on 10 August 2009 and tapering off to a small earthquake of Mw = 4.5 on 2 February 2011 over a period of eighteen months in the intensely seismic Andaman Islands between India and Myanmar. The persisting transient stresses, spatio-temporal seismic pattern, modeled Coulomb stress changes, and the southward migration of earthquake activity has increased the probability of moderate earthquakes recurring in the northern Andaman region, particularly closer to or somewhat south of Diglipur.

What Governs the Spatial and Temporal Distribution of Aftershocks in Mining-Induced Seismicity: Insight into the Influence of Coseismic Static Stress Changes on Seismicity in Kiruna Mine, Sweden

2020 ◽  
Author(s):  
Maria Kozłowska ◽  
Beata Orlecka-Sikora ◽  
Savka Dineva ◽  
Łukasz Rudziński ◽  
Mirjana Boskovic
Keyword(s):  
Induced Seismicity ◽  
Temporal Distribution ◽  
Aftershock Sequence ◽  
State Model ◽  
Induced Earthquakes ◽  
Good Tool ◽  
Coulomb Stress Changes ◽  
Mining Induced Seismicity ◽  
Stress Changes ◽  
Natural Earthquakes

ABSTRACT Strong mining-induced earthquakes are often followed by aftershocks, similar to natural earthquakes. Although the magnitudes of such in-mine aftershocks are not high, they may pose a threat to mining infrastructure, production, and primarily, people working underground. The existing post-earthquake mining procedures usually do not consider any aspects of the physics of the mainshock. This work aims to estimate the rate and distribution of aftershocks following mining-induced seismic events by applying the rate-and-state model of fault friction, which is commonly used in natural earthquake studies. It was found that both the pre-mainshock level of seismicity and the coseismic stress change following the mainshock rupture have strong effects on the aftershock sequence. For mining-induced seismicity, however, we need to additionally account for the constantly changing stress state caused by the ongoing exploitation. Here, we attempt to model the aftershock sequence, its rate, and distribution of two M≈2 events in iron ore Kiruna mine, Sweden. We could appropriately estimate the aftershock sequence for one of the events because both the modeled rate and distribution of aftershocks matched the observed activity; however, the model underestimated the rate of aftershocks for the other event. The results of modeling showed that aftershocks following mining events occur in the areas of pre-mainshock activity influenced by the positive coulomb stress changes, according to the model’s assumptions. However, we also noted that some additional process not incorporated in the rate-and-state model may influence the aftershock sequence. Nevertheless, this type of modeling is a good tool for evaluating the risk areas in mines following a strong seismic event.

Detection and characterization of fluid-driven earthquake clusters

2020 ◽  
Author(s):  
Sebastian Hainzl ◽  
Tomas Fischer
Keyword(s):  
Fluid Flow ◽  
Synthetic Data ◽  
Aftershock Sequence ◽  
Migration Patterns ◽  
Long Valley Caldera ◽  
Epidemic Type Aftershock Sequence ◽  
Aftershock Sequences ◽  
Stress Changes ◽  
Earthquake Sequences ◽  
Earthquake Clusters

<p>Natural earthquake clusters are often related to a mainshock, which triggers the sequence by its induced stress changes. These clusters are called mainshock-aftershock sequences and statistically well explained by earthquake-earthquake interactions according to the Epidemic Type Aftershock Sequence (ETAS) model. Additionally, aseismic processes such as slow slip, dike propagation or fluid flow might also play a role in the initiation and driving of the earthquake sequence. Earthquake swarms, which lacks a dominant earthquake, are often believed to indicate such transient aseismic forcing signals. However, swarm-type clusters can also occur by chance in ETAS-simulations and thus not necessarily related to aseismic drivers. Thus, more sophisticated quantification of the space-time-magnitude characteristics of earthquake sequences are required for discrimination. Migration patterns are one of those properties which can be indicative for aseismic triggering. We suggest simple measures to identify and quantify migration patterns and test those for synthetic data, data from fluid injection experiments, and natural swarm activity related to fluid flow in NW Bohemia and Long Valley caldera. We analyze their potential to discriminate from ETAS-type clusters and compare it with those of time-magnitude characteristics of the activity such as seismic moment ratios and skewness. Our results are finally used to discriminate earthquake clusters in California and elsewhere.</p>

scholarly journals Coulomb static stress changes before and after the 23 October 2011 Van, eastern Turkey, earthquake (<i>M</i><sub>W</sub>= 7.1): implications for the earthquake hazard mitigation

2013 ◽  
Vol 13 (7) ◽  
pp. 1889-1902 ◽  
Author(s):  
M. Utkucu ◽  
H. Durmuş ◽  
H. Yalçın ◽  
E. Budakoğlu ◽  
E. Işık
Keyword(s):  
Earthquake Hazard ◽  
Aftershock Sequence ◽  
Coulomb Stress ◽  
Van Earthquake ◽  
Coulomb Stress Changes ◽  
Stress Shadow ◽  
Eastern Turkey ◽  
Stress Changes ◽  
Before And After ◽  
2011 Van Earthquake

Abstract. Coulomb stress changes before and after the 23 October 2011 Van, eastern Turkey, earthquake have been analysed using available data related to the background and the aftershock seismicity and the source faults. The coseismic stress changes of the background seismicity had slightly promoted stress over the rupture plane of the 2011 Van earthquake, while it yielded a stress shadow over the Gürpı nar Fault which has been argued to have produced the 7 April 1646 Van earthquake. The stress shadow over the Gürp\\i nar fault has become more pronounced following the occurrence of the 2011 Van earthquake, meaning that the repetition of the 1646 Van earthquake has been further suppressed. Spatial distribution and source mechanisms of the 2011 Van earthquake's aftershocks have been utilised to define four clusters with regard to their relative location to the mainshock rupture. In addition, the aftershock sequence covers a much broader area toward the northeast. Correlations between the observed spatial patterns of the aftershocks and the coseismic Coulomb stress changes caused by the mainshock are determined by calculating the stress changes over both optimally oriented and specified fault planes. It is shown here that there is an apparent correlation between the mainshock stress changes and the observed spatial pattern of the aftershock occurrence, demonstrating the usefulness of the stress maps in constraining the likely locations of the upcoming aftershocks and mitigating earthquake hazard.

scholarly journals Modeling active fault systems and seismic events by using a Fiber Bundle model. Example case: Northridge aftershock sequence

2019 ◽  
Author(s):  
Marisol Monterrubio-Velasco ◽  
Ramón Zúñiga ◽  
Carlos Carrasco-Jiménez ◽  
Víctor Márquez-Ramírez ◽  
Josep de la Puente
Keyword(s):  
Fiber Bundle ◽  
Active Faults ◽  
Aftershock Sequence ◽  
Statistical Characteristics ◽  
Real Sequence ◽  
Temporal Correlations ◽  
Self Organized ◽  
Aftershock Sequences ◽  
Fiber Bundle Model ◽  
Spatio Temporal

Abstract. Earthquake aftershocks display spatio-temporal correlations arising from their self-organized critical behavior. Dynamic deterministic modeling of aftershock series is difficult to carry out due to both the physical complexity and uncertainties related to the different parameters which govern the system. Nevertheless, numerical simulations with the help of stochastical models such as the Fiber Bundle (FBM) permit the use of an analog of the physical model that produces a statistical behavior with many similarities with real series. FBM are simple discrete element models that can be characterized by using few parameters. In this work, a new model based on FBM that includes geometrical faults systems is proposed. Our analysis focuses on aftershock statistics in space, time and magnitude domains. To analyze the model behavior a parametric study is carried out. Moreover, we analyzed the synthetic aftershock sequences properties assuming initial load configurations and suitable conditions to propagate the rupture. As an example case, we have modeled a set of real active faults related to the Northridge, California, earthquake sequence. We compare the simulation results to statistical characteristics from the Northridge sequence determining which range of parameters in our FBM version reproduce the main features observed in real aftershock series. In order to reproduce statistical characteristics of the real sequence larger πfrac values (0.85 

Cephalonia-lefkas Transform Fault Zone (CLTFZ) Complexity: Insights from 2015 Lefkas Earthquake Sequence

2019 ◽  
pp. 1-12
Author(s):  
Andreas Karakonstantis ◽  
Kyriaki Pavlou ◽  
Vasilis Kapetanidis ◽  
Georgios Bozionelos
Keyword(s):  
Fault Zone ◽  
Aftershock Sequence ◽  
Deformation Pattern ◽  
Transform Fault ◽  
Minimization Method ◽  
Epicentral Area ◽  
Coulomb Stress Changes ◽  
Major Earthquake ◽  
Stress Changes ◽  
Transform Fault Zone

In order to define a better model for the Cephalonia-Lefkas Transform Fault Zone the sequence of 2015 Lefkas earthquake was examined. On 17 November 2015 (07:10 GMT) a major earthquake (Mw=6.4) occurred on the central-western part of Lefkas island. Several destructive events were located in the past in this fault zone, so an extensive seismotectonic study is feasible for that area. Manual analysis was performed using a custom velocity model that was determined for that purpose, applying the average travel-time residuals and location uncertainties errors minimization method. Several clusters belonging to the aftershock sequence were identified, whereas three are directly related to the causative fault, covering an area of about 25 km. The central one, which includes the mainshock, comprises of only a few aftershocks. The northern, within which the majority of aftershocks are located, lies in the central part of Lefkas island and the southern occurred close to the SW edge of the island. In addition, offshore clusters with distinct characteristics have been identified to the south, between Lefkas and Cephalonia islands. The temporal evolution of the aftershock sequence indicates that no migration was observed, given that after the occurrence of the mainshock the entire epicentral area was activated. Focal mechanisms of the Seismological Laboratory of the University of Athens showed dextral strike-slip faulting for both mainshock and major aftershocks of the sequence. Taking into account the spatial distribution of the aftershocks, supported by the tectonic and geomorphological settings of the region, a deformation pattern, consisting of the Cephalonia-Lefkas and Ithaca-Lefkas major fault zones which converge in the area of Vassiliki bay is proposed. The appearance of the southernmost clusters was interpreted by the positive Coulomb stress changes transfer due to major earthquake Mw=6.4.

Earthquake clusters expected from bare statistics: How bursts and swarms emerge from exogenous and epidemic aftershock processes.

2021 ◽  
Author(s):  
Jordi Baro
Keyword(s):  
Heat Flow ◽  
Solid Earth ◽  
Point Process ◽  
Branching Process ◽  
Aftershock Sequence ◽  
Statistical Properties ◽  
Etas Model ◽  
Stress Changes ◽  
Earthquake Clusters ◽  
Statistical Laws

&lt;p&gt;Earthquake catalogs exhibit strong spatio-temporal correlations. As such, earthquakes are often classified into clusters of correlated activity. Clusters themselves are traditionally classified in two different kinds: (i) bursts, with a clear hierarchical structure between a single strong mainshock, preceded by a few foreshocks and followed by a power-law decaying aftershock sequence, and (ii) swarms, exhibiting a non-trivial activity rate that cannot be reduced to such a simple hierarchy between events.&amp;#160;&lt;/p&gt;&lt;p&gt;The Epidemic Aftershock Sequence (ETAS) model is a linear Hawkes point process able to reproduce earthquake clusters from empirical statistical laws [Ogata, 1998]. Although not always explicit, the ETAS model is often interpreted as the outcome of a background activity driven by external forces and a Galton-Watson branching process with one-to-one causal links between events [Saichev et al., 2005]. Declustering techniques based on field observations [Baiesi &amp; Paczuski, 2004] can be used to infer the most likely causal links between events in a cluster. Following this method, Zaliapin and Ben&amp;#8208;Zion (2013) determined the statistical properties of earthquake clusters characterizing bursts and swarms, finding a relationship between the predominant cluster-class and the heat flow in seismic regions.&lt;/p&gt;&lt;p&gt;Here, I show how the statistical properties of clusters are related to the fundamental statistics of the underlying seismogenic process, modeled in two point-process paradigms [Bar&amp;#243;, 2020].&lt;/p&gt;&lt;p&gt;The classification of clusters into bursts and swarms appears naturally in the standard ETAS model with homogeneous rates and are determined by the average branching ratio (nb) and the ratio between exponents &amp;#945; and b characterizing the production of aftershocks and the distribution of magnitudes, respectively. The scale-free ETAS model, equivalent to the BASS model [Turcotte, et al., 2007], and usual in cold active tectonic regions, is imposed by &amp;#945;=b and reproduces bursts. In contrast, by imposing &amp;#945;&lt;0.5b, we recover the properties of swarms, characteristic of regions with high heat flow.&amp;#160;&lt;/p&gt;&lt;p&gt;Alternatively, the same declustering methodology applied to a non-homogeneous Poisson process with a non-factorizable intensity, i.e. in absence of causal links, recovers swarms with &amp;#945;=0, i.e. a Poisson Galton-Watson process, with similar statistical properties to the ETAS model in the regime &amp;#945;&lt;0.5b.&lt;/p&gt;&lt;p&gt;Therefore, while bursts are likely to represent actual causal links between events, swarms can either denote causal links with low &amp;#945;/b ratio or variations of the background rate caused by exogenous processes introducing local and transient stress changes. Furthermore, the redundancy in the statistical laws can be used to test the hypotheses posed by the ETAS model as a memory&amp;#8208;less branching process.&amp;#160;&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;ul&gt;&lt;li&gt; &lt;p&gt;Baiesi, M., &amp; Paczuski, M. (2004). &lt;em&gt;Physical Review E&lt;/em&gt;, 69, 66,106. doi:10.1103/PhysRevE.69.066106.&lt;/p&gt; &lt;/li&gt; &lt;li&gt; &lt;p&gt;Bar&amp;#243;, J. (2020).&amp;#160; &lt;em&gt;Journal of Geophysical Research: Solid Earth,&lt;/em&gt; 125, e2019JB018530. doi:10.1029/2019JB018530.&lt;/p&gt; &lt;/li&gt; &lt;li&gt; &lt;p&gt;Ogata, Y. (1998) &lt;em&gt;Annals of the Institute of Statistical Mathematics,&lt;/em&gt; 50(2), 379&amp;#8211;402. doi:10.1023/A:1003403601725.&lt;/p&gt; &lt;/li&gt; &lt;li&gt; &lt;p&gt;Saichev, A., Helmstetter, A. &amp; Sornette, D. (2005) &lt;em&gt;Pure appl. geophys.&lt;/em&gt; 162, 1113&amp;#8211;1134. doi:10.1007/s00024-004-2663-6.&lt;/p&gt; &lt;/li&gt; &lt;li&gt; &lt;p&gt;Turcotte, D. L., Holliday, J. R., and Rundle, J. B. (2007), &lt;em&gt;Geophys. Res. Lett.&lt;/em&gt;, 34, L12303, doi:10.1029/2007GL029696.&lt;/p&gt; &lt;/li&gt; &lt;li&gt; &lt;p&gt;Zaliapin, I., and Ben&amp;#8208;Zion, Y. (2013), &lt;em&gt;J. Geophys. Res. Solid Earth&lt;/em&gt;, 118, 2865&amp;#8211; 2877, doi:10.1002/jgrb.50178.&lt;/p&gt; &lt;/li&gt; &lt;/ul&gt;

Seismic doublets and a complex seismic sequence controlled by the rotation of the Juan Fernández microplate

2021 ◽  
Author(s):  
Simone Cesca ◽  
Carla Valenzuela Malebrán ◽  
José Ángel López-Comino ◽  
Timothy Davis ◽  
Carlos Tassara ◽  
...  
Keyword(s):  
Source Parameters ◽  
Strike Slip ◽  
Focal Mechanisms ◽  
Joint Analysis ◽  
Seismic Sequence ◽  
Local Data ◽  
Study Region ◽  
Coulomb Stress Changes ◽  
Earthquake Source Parameters ◽  
Stress Changes

&lt;p&gt; A complex seismic sequence took place in 2014 at the Juan Fern&amp;#225;ndez microplate, a small microplate located between Pacific, Nazca and Antarctica plates. Despite the remoteness of the study region and the lack of local data, we were able to resolve earthquake source parameters and to reconstruct the complex seismic sequence, by using modern waveform-based seismological techniques. The sequence started with an exceptional Mw 7.1-6.7 thrust &amp;#8211; strike slip earthquake doublet, the first subevent being the largest earthquake ever recorded in the region and one of the few rare thrust earthquakes in a region otherwise characterized by normal faulting and strike slip earthquakes. The joint analysis of seismicity and focal mechanisms suggest the activation of E-W and NE-SW faults or of an internal curved pseudofault, which is formed in response to the microplate rotation, with alternation of thrust and strike-slip earthquakes. Seismicity migrated Northward in its final phase, towards the microplate edge, where a second doublet with uneven focal mechanisms occurred. The sequence rupture kinematics is well explained by Coulomb stress changes imparted by the first subevent. Our analysis show that compressional stresses, which have been mapped at the northern boundary of the microplate, but never accompanied by large thrust earthquakes, can be accommodated by the rare occurrence of large, impulsive, shallow thrust earthquakes, with a considerable tsunamigenic potential.&lt;/p&gt;

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