Future Ruptures Research Articles

Boundary Work in the Nordic Media Model: Metajournalistic Discourse on Alternative Media in Denmark, Norway, and Sweden

ABSTRACT The increasing prominence of alternative news media has been identified as a particular challenge to contemporary established journalism, next to collapsing financial models, platform dependency, falling levels of trust and increased competition. Against this background, this study examines how news editors from 23 established news organizations in Sweden, Norway, and Denmark view the rise and role of alternative news media and thereby the boundaries of the journalistic field. Combining strategic action field theory, boundary work and the concept of metajournalistic discourse, it identifies three metajournalistic discourses—We are the (real) journalists, We are in control (for now), and We are under pressure. Together, these metajournalistic discourses portray alternative news media as a challenge that largely has been overcome, and as currently insignificant actors that clearly do not represent “real journalism”. At the same time, the discourses also display concerns that alternative news media might represent potential future field ruptures via their association with broader potentially detrimental media developments, such as genre-confused media audiences or harassment of journalists.

A rapid analysis of aftershock processes after a moderate magnitude earthquake with ML methods

SUMMARY Moderate magnitude earthquakes and seismic sequences frequently develop on fault systems, but whether they are linked to future major ruptures is always ambiguous. In this study, we investigated a seismic sequence that has developed within a portion of the stretching region of the Apennines in Italy where moderate to large earthquakes are likely to occur. We captured a total of 2039 aftershocks of the 2023 September 18, Mw 4.9 earthquake occurred during the first week, by using machine-learning (ML) based algorithms. Aftershocks align on two 5–7 km long parallel faults, from a length that exceeds what is expected from the main shock magnitude. The segments are ramping at about 6 km depth on closely spaced N100 striking 70 N dipping planes, at a distance of some kilometres from the main shock hypocentre. Our results indicate that even moderate magnitude events trigger seismicity on a spread set of fault segments around the main shock hypocentre, revealing processes of interaction within the crustal layer. The possibility that larger earthquakes develop during seismicity spread is favoured by pore pressure diffusion, in relation with the closeness to criticality of fault segments. Based on the very rapid activation of seismicity on the entire system and a back-front signal from the hypocentre of the main event, we infer that fluid pressure, initially high within the crustal layer, rapidly dropped after the main shock. Our study reinforces the importance of timely extracting information on fault geometry and seismicity distribution on faults. ML-based methods represent a viable tool for semi-real-time application, yielding constraints on short-time forecasts.

New Zealand Fault-Rupture Depth Model v.1.0: A Provisional Estimate of the Maximum Depth of Seismic Rupture on New Zealand’s Active Faults

ABSTRACT We summarize estimates of the maximum rupture depth on New Zealand’s active faults (“New Zealand Fault-Rupture Depth Model v.1.0”), as used in the New Zealand Community Fault Model v1.0 and as a constraint for the latest revision of the New Zealand National Seismic Hazard Model (NZ NSHM 2022). Rupture depth estimates are based on a combination of two separate model approaches (using different methods and datasets). The first approach uses regional seismicity distribution from a relocated earthquake catalog to calculate the 90% seismicity cutoff depth (D90), representing the seismogenic depth limit. This is multiplied by an overshoot factor representing the dynamic propagation of rupture into the conditional stability zone, and accounting for the difference between regional seismicity depths and the frictional properties of a mature fault zone to arrive at a seismic estimate of the maximum rupture depth. The second approach uses surface heat flow and rock type to compute depths that correspond to the thermal limits of frictional instabilities on seismogenic faults. To arrive at a thermally-based maximum rupture depth, these thermal limits are also multiplied by an overshoot factor. Both the models have depth cutoffs at the Moho and/or subducting slabs. Results indicate the maximum rupture depths between 8 (Taupō volcanic zone) and >30 km (e.g., southwest North Island), strongly correlated with regional thermal gradients. The depths derived from the two methods show broad agreement for most of the North Island and some differences in the South Island. A combined model using weighting based on relative uncertainties is derived and validated using constraints from hypocenter and slip model depths from recent well-instrumented earthquakes. We discuss modifications to the maximum rupture depths estimated here that were undertaken for application within the NZ NSHM 2022. Our research demonstrates the utility of combining seismicity cutoff and thermal stability estimates to assess the down-dip dimensions of future earthquake ruptures.

Shallow Slow Slip Events Identified Offshore the Osa Peninsula in Southern Costa Rica From GNSS Time Series

AbstractUsing new continuous geodetic time series, we identify five shallow slow slip events (SSEs) offshore and beneath the Osa peninsula in southern Costa Rica. An early event was detected by one station in 2013, and two events occurring in close succession in both 2018 and 2022 were detected by multiple stations, indicating a preliminary recurrence interval of ∼4–5 years. While SSEs have been observed to the northwest at Nicoya, this is their first documentation in southern Costa Rica. Modeled slip distributions of the 2018 and 2022 events indicate they likely ruptured the same or overlapping patches of the plate interface, near the trench, updip of the 1983 Mw 7.4 Osa event. Immediately offshore, estimated cumulative slip from the 2018 and 2022 events is sufficient to close the slip deficit from tectonic loading over the recurrence interval, potentially limiting the magnitude and spatial slip distribution of future large ruptures.

Evaluating how well active fault mapping predicts earthquake surface-rupture locations

Abstract Earthquake surface-fault rupture location uncertainty is a key factor in fault displacement hazard analysis and informs hazard and risk mitigation strategies. Geologists often predict future rupture locations from fault mapping based on the geomorphology interpreted from remote-sensing data sets. However, surface processes can obscure fault location, fault traces may be mapped in error, and a future rupture may not break every fault trace. We assessed how well geomorphology-based fault mapping predicted surface ruptures for seven earthquakes: 1983 M 6.9 Borah Peak, 2004 M 6.0 Parkfield, 2010 M 7.2 El Mayor–Cucapah, 2011 M 6.7 Fukushima-Hamadori, 2014 M 6.0 South Napa, 2016 M 7.8 Kaikoura, and 2016 M 7 Kumamoto. We trained geoscience students to produce active fault maps using topography and imagery acquired before the earthquakes. A geologic professional completed a “control” map. Mappers used a new “geomorphic indicator ranking” approach to rank fault confidence based on geomorphologic landforms. We determined the accuracy of the mapped faults by comparing the fault maps to published rupture maps. We defined predicted ruptures as ruptures near a fault (50–200 m, depending on the fault confidence) that interacted with the landscape in a similar way to the fault. The mapped faults predicted between 12% to 68% of the principal rupture length for the studied earthquakes. The median separation distances between predicted ruptures and strong, distinct, or weak faults were 15–30 m. Our work highlights that mapping future fault ruptures is an underappreciated challenge of fault displacement hazard analysis—even for experts—with implications for risk management, engineering site assessments, and fault exclusion zones.

MCQsim: A Multicycle Earthquake Simulator

ABSTRACT Multicycle earthquake rupture simulators generate long sequences of earthquakes along predefined fault geometries for statistical analysis of earthquake recurrence and related rupture characteristics. Based on the physical approximations of long-term crustal deformation and the short-term rupture process, they can provide a deeper understanding of the inner workings of the “earthquake machine” as well as inform seismic hazard assessment by filling the observational gap between instrumental seismology and paleoseismology. With MCQsim, we introduce a multi-cycle rupture simulator that (a) can work with complex, nonplanar fault geometries and heterogenous models of fault strength, (b) includes different approximations of long-term stress accumulation, (c) incorporates elastic signal propagation velocity, (d) distinguishes between stable, conditionally stable, and unstable portions of the fault, and (e) includes postseismic relaxation and afterslip. The generated earthquake catalogs allow the identification of parameters that dominate system behavior while also providing probabilities of future ruptures based on their preceding behavior. Here, we focus on the technical aspects of how MCQsim, which is based on elastostatic dislocation theory and the boundary element method, approximates both the seismic cycle and the earthquake’s rupture process. We provide exemplary simulation outputs for verification and validation purposes.

Old dike swarms could influence future fault ruptures

Old dike swarms could influence future fault ruptures

Shortcut Faults and Lateral Spreading Activated in a Pull-Apart Basin by the 2018 Palu Earthquake, Central Sulawesi, Indonesia

Our understanding of pull-apart basins and their fault systems has been enhanced by analog experiments and simulations. However, there has been scarce interest to compare the faults that bound pull-apart basins with surface ruptures during earthquakes. In this study, we investigated the effects of a 2018 earthquake (Mw 7.5) on a pull-apart basin in the Palu–Koro fault system, Sulawesi Island, Indonesia, using geomorphic observations on digital elevation models and optical correlation with pre- and post-earthquake satellite images. A comparison of active fault traces determined by geomorphology with the locations of surface ruptures from the 2018 earthquake shows that some of the boundary faults of the basin are inactive and that active faulting has shifted to basin-shortcut faults and relay ramps. We also report evidence of lateral spreading, in which alluvial fan materials moved around the end of the alluvial fan. These phenomena may provide insights for anticipating the location of future surface ruptures in pull-apart basins.

Correlation of porosity variations and rheological transitions on the southern Cascadia megathrust

The unknown onshore extent of megathrust earthquake rupture in the Cascadia subduction zone represents a key uncertainty in earthquake hazard for the Pacific Northwest that is governed by the physical state and mechanical properties of the plate interface. The Cascadia plate interface is segmented into an interseismically locked zone located primarily offshore that is expected to rupture in large earthquakes, a region of aseismic slow slip at greater depth, and an intervening transition zone of uncertain rupture potential. Here we image the evolution of the ratio of seismic compressional to shear wave velocities from the locked zone to the transition zone, which is related to changes in fluid content of the plate boundary zone, using a dense onshore–offshore seismic dataset from southernmost Cascadia. The locked zone shows evidence of high fluid content implying a high porosity, yet the downdip transition zone shows an order of magnitude lower porosity. This strong variation is consistent with models that contain a ductile region between the earthquake rupture and slow slip zones that would inhibit onshore propagation of future large earthquake ruptures and hence reduce seismic hazard. The transition between the locked and slowly slipping regions of the southern Cascadia megathrust has a lower porosity than these regions, according to seismic imaging. This suggests that the transition area is ductile, which may limit rupture propogation.

Spontaneous index finger extensor tendon rupture in a SNAC wrist

We present two recent cases of spontaneous rupture of both index finger extensor digitorum communis and extensor indices proprius tendons caused by a dorsal carpus osteophyte. Both patients had a history of scaphoid fracture non-union with evolution to scaphoid non-union advanced collapse (SNAC) of the wrist. These two cases were treated surgically with a 3-corner arthrodesis, and an interposition of a fragment of one of both ruptured tendons together with a tendon transfer of a supernumerary extensor digitorum communis of the third finger. The interposed tendon fragment was sutured with a Pulvertaft weave proximally and end-to-end distally. The supernumerary tendon was added as reinforcement to this construction. At 6-month and 14-month follow-up, the patients had a slight decrease in range of motion and functionality without hindering the activities of daily living and a great improvement in strength. Isolated extension of the index finger was possible minimum 6 months postoperatively. Spontaneous tendon ruptures of the finger extensors are not common but were described earlier in literature. Recent literature described that underlying cause of a spontaneous tendon rupture should always be corrected in order to prevent or at least delay future ruptures. To our knowledge, this is a rare type of complication and this kind of treatment has never been reported in literature.

Importance of shear-wave elastography in prediction of Achilles tendon rupture.

It was demonstrated that about 6% of patients with a ruptured Achilles tendon experience the rupture of contralateral tendon in the future; the aim of this study was to estimate the risk for rupture of contralateral tendon in patients who underwent surgical reconstruction of ruptured Achilles tendon by using subjective questionnaires and shear-wave elastography. Twenty-four patients who underwent surgical repair of the ruptured Achilles tendon and twelve age-matched healthy controls were examined with ultrasound SWE. Functional outcomes were assessed with American Orthopedic Foot and Ankle Society (AOFAS) scoring system and subjective rating system which we introduced and validated. The elasticity of injured tendon was markedly decreased (by 42%) compared to the contralateral tendon of the patient, as expected. Both AOFAS score and our novel subjective assessment scale positively correlate with ultrasound SWE values in ruptured Achilles tendons. The elasticity of contralateral Achilles tendons in patients was 23% lower than among healthy individuals. Irrespective of the lack of difference in the subjective feeling assessed by AOFAS, the contralateral tendon in the patients with reconstructed Achilles tendon has significantly lower stiffness than healthy individuals. Therefore, contralateral tendons in patients who suffered from rupture are more prone to future ruptures.

Changes in Seismicity Pattern Due to the 2016 Kumamoto Earthquakes Identify a Highly Stressed Area on the Hinagu Fault Zone

AbstractA highly stressed area where eventual ruptures have often been observed to nucleate is characterized by low b values of earthquake frequency‐size distribution. Crustal deformation due to the occurrence of large earthquakes causes stress perturbation in nearby regions, so an investigation into spatiotemporal b values can play a crucial role in the distribution of postseismic hazards after the 2016 Kumamoto earthquake sequence along the Futagawa‐Hinagu fault zone, which culminated in the magnitude 7.3 mainshock. Together with an analysis of aftershock decay p value that can be used to infer stressing history, a highly stressed area with a characteristic dimension of 10 km at the southern end of the causative faults was found. Our observation is explained by postseismic deformation due to an afterslip on the causative faults and viscoelastic relaxation model. Similar to the Kumamoto mainshock rupture, which started at a low‐b‐value area, the observed highly stressed area shows a high likelihood of future earthquake ruptures.

Kinematic analysis of secondary faults within a distributed shear-zone reveals fault linkage and increased seismic hazard

Complex multifault earthquake ruptures involving secondary faults emphasize the necessity to characterize their seismogenic potential better and study their relationship with major faults to improve the seismic hazard assessment of a region. High-resolution geophysical data were interpreted to make a detailed characterization of the Averroes Fault and the North Averroes Faults, which are poorly known secondary right-lateral strike-slip faults located in the central part of the Alboran Sea (western Mediterranean). These faults appear to have evolved since the Pliocene as part of a distributed dextral strike-slip shear zone in response to local strain engendered by the diverging movement of the Carboneras Fault to the north, and the Yusuf and Alboran Ridge faults to the south. In addition, the architecture of these faults suggests that the Averroes Fault may eventually link with the Yusuf fault, thus leading to a higher seismogenic potential. Therefore, these secondary faults represent a hitherto unrecognized seismogenic hazard since they could produce earthquakes up to moment magnitude (Mw) 7.6. Our results highlight the importance of the role played by secondary faults in a specific kinematic framework. Their reciprocal linkage and their mechanical relationship with the main faults could lead to future complex fault ruptures. This information could improve fault source and earthquake models used in seismic and tsunami hazard assessment in this and similar regions.

Seismic constraints on the architecture of the Newport‐Inglewood/Rose Canyon fault: Implications for the length and magnitude of future earthquake ruptures

AbstractThe Newport‐Inglewood/Rose Canyon (NIRC) fault zone is an active strike‐slip fault system within the Pacific‐North American plate boundary in Southern California, located in close proximity to populated regions of San Diego, Orange, and Los Angeles counties. Prior to this study, the NIRC fault zone's continuity and geometry were not well constrained. Nested marine seismic reflection data with different vertical resolutions are employed to characterize the offshore fault architecture. Four main fault strands are identified offshore, separated by three main stepovers along strike, all of which are 2 km or less in width. Empirical studies of historical ruptures worldwide show that earthquakes have ruptured through stepovers with this offset. Models of Coulomb stress change along the fault zone are presented to examine the potential extent of future earthquake ruptures on the fault zone, which appear to be dependent on the location of rupture initiation and fault geometry at the stepovers. These modeling results show that the southernmost stepover between the La Jolla and Torrey Pines fault strands may act as an inhibitor to throughgoing rupture due to the stepover width and change in fault geometry across the stepover; however, these results still suggest that rupture along the entire fault zone is possible.

Earthquake ground motion amplification for surface waves

AbstractSurface waves from earthquakes are known to cause strong damage, especially for larger structures such as skyscrapers and bridges. However, common practice in characterizing seismic hazard at a specific site considers the effect of near‐surface geology on only vertically propagating body waves. Here we show that surface waves have a unique and different frequency‐dependent response to known geologic structure and that this amplification can be analytically calculated in a manner similar to current hazard practices. Applying this framework to amplification in the Los Angeles Basin, we find that peak ground accelerations for certain large regional earthquakes are underpredicted if surface waves are not properly accounted for and that the frequency of strongest ground motion amplification can be significantly different. Including surface‐wave amplification in hazards calculations is therefore essential for accurate predictions of strong ground motion for future San Andreas Fault ruptures.

Crustal structure and deformation across a mature slab tear zone: the case of southern Tyrrhenian subduction (Italy)

AbstractWe compute S velocity profiles of the crust across the Messina Strait (Italy), the tear zone at the southern end of the Ionian subduction zone. Separating Sicily from Calabria, the Messina Strait hosted some of the strongest earthquakes to ever occur in Italy. Here the motion of the Ionian slab with respect to Sicily creates a complex tectonic setting characterized by lithospheric tearing. We show velocity models of the crust, computed from teleseismic receiver function inversion, outlining the differences between Sicily and Calabria. Strong deformation across the Messina Strait between 10–15 and 30 km depth is expressed by strong anisotropy (up to 10%), developed in a ductile shear zone of the crust. The top of these ductile weaker layers could limit the depth extent of future ruptures.

SUBSTANTIVE DUE PROCESS, BLACK SWANS, AND INNOVATION

Substantive due process is a vexing concept within constitutional law that has at times been mocked as an “oxymoron,” and recently re-anchored to American “tradition” and “history.” Yet the Court has refused to renounce the doctrine entirely, and has continued to apply it in a manner that considers evolutionary notions of “ordered liberty.” This Essay endorses “evolutionary” due process, though on new grounds. It recognizes that evolutionary due process reflects our actual constitutional practices – a point made by many commentators – but it also permits innovation as necessary to cope with so-called “Black Swan” events. All “living Constitution” arguments rest on the argument that the Constitution was meant to breathe, to accommodate and sometimes hasten cultural change. But these accounts tend to reflect optimism about cultural change, and about the Court’s ability to advance that progress. These tales ignore another, darker kind of change, which likewise requires that decision makers innovate: ominous, potentially cataclysmic outlier events that likewise occur throughout history. These “Black Swan” events tend to be repressed or exoticized in conventional constitutional histories, rather than appearing as part of the normal life cycle of our constitutional order. A fuller account of our history requires that we weave these outlier events into our historical narratives, and develop constitutional theories that recognize the fact of past ruptures and the inevitability of future ruptures. The Essay also explores the inherent limitations of the past as a guide to the future, and the special limitations of judges and lawyers to engaged in balanced historical analysis. Contemporary fascination with constitutional history as a means of determining constitutional meaning makes it especially critical that we are reminded of these inherent limitations, and that we consider more generally our forebearers’ willingness to “think anew.” This American constitutional spirit of renewal and innovation may be most apparent in times of crisis, but it never wholly disappears. Room for that spirit’s expression should be explicitly preserved in our due process principles going forward, lest we compromise future generations’ ability to cope candidly and effectively with the escalating forces of change.

Drug Eluting Stents for Vulnerable Plague

A vulnerable plaque is an atheromatic plaque with specific morphological characteristics, mainly presented as an unstable collection of white blood cells and lipids in the wall of an artery. It is of great importance to adequately recognize and treat this entity before its rupture, before the initiation of an acute coronary syndrome. The search of the location of future plaque ruptures or plaque erosions is an important area of cardiovascular research. Systemic therapy, including use of statins, targets the vulnerable patient. However, adverse events cannot be completely eliminated with the appropriate application of systemic therapies and this has given rise to efforts for evolution of local or regional therapies of the vulnerable plaques to prevent future events. Recently drug eluting stents dedicated to vulnerable plaques have been developed, aiming in the local stabilization of the vulnerable plaque.

2010 Maule earthquake slip correlates with pre-seismic locking of Andean subduction zone

The magnitude-8.8 Maule (Chile) earthquake of 27 February 2010 ruptured a segment of the Andean subduction zone megathrust that has been suspected to be of high seismic potential. It is the largest earthquake to rupture a mature seismic gap in a subduction zone that has been monitored with a dense space-geodetic network before the event. This provides an image of the pre-seismically locked state of the plate interface of unprecedentedly high resolution, allowing for an assessment of the spatial correlation of interseismic locking with coseismic slip. Pre-seismic locking might be used to anticipate future ruptures in many seismic gaps, given the fundamental assumption that locking and slip are similar. This hypothesis, however, could not be tested without the occurrence of the first gap-filling earthquake. Here we show evidence that the 2010 Maule earthquake slip distribution correlates closely with the patchwork of interseismic locking distribution as derived by inversion of global positioning system (GPS) observations during the previous decade. The earthquake nucleated in a region of high locking gradient and released most of the stresses accumulated in the area since the last major event in 1835. Two regions of high seismic slip (asperities) appeared to be nearly fully locked before the earthquake. Between these asperities, the rupture bridged a zone that was creeping interseismically with consistently low coseismic slip. The rupture stopped in areas that were highly locked before the earthquake but where pre-stress had been significantly reduced by overlapping twentieth-century earthquakes. Our work suggests that coseismic slip heterogeneity at the scale of single asperities should indicate the seismic potential of future great earthquakes, which thus might be anticipated by geodetic observations.

Pre-existing cross-structures and active fault segmentation in the northern-central Apennines (Italy)

The multideformed axial zone of the Apennines provides a great opportunity to explore the influence of pre-existing cross-structures (inherited from pre-Quaternary tectonic phases) on the segmentation of Quaternary/active seismogenic extensional faults. Detailed geological and structural data and their comparison with seismological data show that although the attitudes (strike and dip) of oblique pre-existing faults are certainly an important factor in determining a segment boundary, the size of the inherited oblique structures seems to be more crucial. Pre-existing cross-structures with lengths ranging from several kilometers to a few tens of kilometers show a twofold behavior. They can act as segment barriers during the rupture of a single fault segment or they can be reactivated as transfer zones inducing the activation of two adjacent segments that belong to the same fault system. Regional basement/crustal oblique pre-existing cross-structures, with lengths ranging from several tens of kilometers to hundreds of kilometers (commonly NNE-striking), may act as “persistent structural barriers” that halt both fault segment and fault system propagation, thus determining their terminations and maximum sizes. In the northern-central Apennines, the NNE-striking Ancona–Anzio, Valnerina, and Ortona–Roccamonfina tectonic lineaments, although having been repeatedly reactivated since the Mesozoic, represent the most important examples of these structures. Moreover, probably due to their misorientation with respect to the present extensional stress field, regional NNE-striking pre-existing structures appear to be less likely to produce strong magnitude events (no surface evidence for Quaternary faulting has been found thus far and historical and instrumental seismicity shows only M < 6 events). M ~ 7 event, on the other hand, is more likely to occur along the (N)NW–(S)SE trending normal fault systems. Lastly, we propose a model that can explain the different sizes of fault segments and fault systems on the basis of their location with respect to the “persistent structural barriers” and their spacing. In this view, our results may contribute to a more reasonable assessment of the nature and size of future surface ruptures in the northern-central Apennines, which are of critical importance to estimating seismic hazard.