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Faults & earthquakes

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At least 1,171 records · Page 65Linked to original sources

USGS1993

Near-field investigations of the Landers earthquake sequence, April to July 1992

The Landers earthquake, which had a moment magnitude ( M w ) of 7.3, was the largest earthquake to strike the contiguous United States in 40 years. This earthquake resulted from the rupture of five major and many minor right-lateral faults near the southern end of the eastern California shear zone, just north of the San Andreas fault. Its M w 6.1 preshock and M w 6.2 aftershock had their own aftershocks and foreshocks. Surficial geological observations are consistent with local and far-field seismologic observations of the earthquake. Large surficial offsets (as great as 6 meters) and a relatively short rupture length (85 kilometers) are consistent with seismological calculations of a high stress drop (200 bars), which is in turn consistent with an apparently long recurrence interval for these faults.

California↗

USGS2017

Accelerating slip rates on the puente hills blind thrust fault system beneath metropolitan Los Angeles, California, USA

Slip rates represent the average displacement across a fault over time and are essential to estimating earthquake recurrence for proba-bilistic seismic hazard assessments. We demonstrate that the slip rate on the western segment of the Puente Hills blind thrust fault system, which is beneath downtown Los Angeles, California (USA), has accel-erated from ~0.22 mm/yr in the late Pleistocene to ~1.33 mm/yr in the Holocene. Our analysis is based on syntectonic strata derived from the Los Angeles River, which has continuously buried a fold scarp above the blind thrust. Slip on the fault beneath our field site began during the late-middle Pleistocene and progressively increased into the Holocene. This increase in rate implies that the magnitudes and/or the frequency of earthquakes on this fault segment have increased over time. This challenges the characteristic earthquake model and presents an evolving and potentially increasing seismic hazard to metropolitan Los Angeles.

California↗

USGS2006

Rupture propagation of the 2004 Parkfield, California, earthquake from observations at the UPSAR

Using a short-baseline seismic array (U.S. Geological Survey Parkfield Dense Seismograph Array [UPSAR]) about 12 km west of the rupture initiation of the 28 September 2004 M 6.0 Parkfield, California, earthquake, we have observed the movement of the rupture front of this earthquake on the San Andreas fault. The sources of high-frequency arrivals at UPSAR, which we use to identify the rupture front, are mapped onto the San Andreas fault using their apparent velocity and back azimuth. Measurements of apparent velocity and back azimuth are calibrated using aftershocks, which have a compact source and known location. Aftershock back azimuths show considerable lateral refraction, consistent with a high-velocity ridge on the southwest side of the fault. We infer that the initial mainshock rupture velocity was approximately the Rayleigh speed (with respect to slower side of the fault), and the rupture then slowed to about 0.66?? near the town of Parkfield after 2 sec. The last well-correlated pulse, 4 sec after S, is the largest at UPSAR, and its source is near the region of large accelerations recorded by strong-motion accelerographs and close to northern extent of continuous surface fractures on the southwest fracture zone. Coincidence of sources with preshock and aftershock distributions suggests fault material properties control rupture behavior. High-frequency sources approximately correlate with the edges of asperities identified as regions of high slip derived from inversion of strong-motion waveforms.

Bulletin of the Seismological Society of America↗

USGS2008

The 1906 San Francisco earthquake a century later: Introduction to the special section

The great 1906 San Francisco earthquake is perhaps the landmark event in the history of earthquake science. It began with a foreshock at 5:12 a.m. local time in the morning of 18 April 1906. Some 30 sec later, the main event initiated on the San Andreas fault, just off the San Francisco coast ( Lawson, 1908 ). Within 90 sec, nearly 480 km of the San Andreas fault ruptured (see Fig. 1 ), extending south to the northern end of the creeping section near San Juan Bautista and north to the terminus of the fault at the triple junction near Cape Mendocino ( Song et al. , 2008 ). As it ruptured, it generated powerful seismic waves over the entire rupture length and set in motion a chain of events that led to the destruction of most of San Francisco, the largest city of the western United States at the time. The earthquake occurred in the early days of instrumental seismology, which renders the data difficult to analyze, but our best estimate is that the moment magnitude was 7.9 ( Song et al. , 2008 ), about 26 times the size of the 1989 magnitude 6.9 Loma Prieta earthquake as measured by seismic moment ( Hanks and Krawinkler, 1991 ; Song et al. , 2008 ).

California↗

USGS2015

Ground motion-simulations of 1811-1812 New Madrid earthquakes, central United States

We performed a suite of numerical simulations based on the 1811–1812 New Madrid seismic zone (NMSZ) earthquakes, which demonstrate the importance of 3D geologic structure and rupture directivity on the ground‐motion response throughout a broad region of the central United States (CUS) for these events. Our simulation set consists of 20 hypothetical earthquakes located along two faults associated with the current seismicity trends in the NMSZ. The hypothetical scenarios range in magnitude from M 7.0 to 7.7 and consider various epicenters, slip distributions, and rupture characterization approaches. The low‐frequency component of our simulations was computed deterministically up to a frequency of 1 Hz using a regional 3D seismic velocity model and was combined with higher‐frequency motions calculated for a 1D medium to generate broadband synthetics (0–40 Hz in some cases). For strike‐slip earthquakes located on the southwest–northeast‐striking NMSZ axial arm of seismicity, our simulations show 2–10 s period energy channeling along the trend of the Reelfoot rift and focusing strong shaking northeast toward Paducah, Kentucky, and Evansville, Indiana, and southwest toward Little Rock, Arkansas. These waveguide effects are further accentuated by rupture directivity such that an event with a western epicenter creates strong amplification toward the northeast, whereas an eastern epicenter creates strong amplification toward the southwest. These effects are not as prevalent for simulations on the reverse‐mechanism Reelfoot fault, and large peak ground velocities (>40  cm/s) are typically confined to the near‐source region along the up‐dip projection of the fault. Nonetheless, these basin response and rupture directivity effects have a significant impact on the pattern and level of the estimated intensities, which leads to additional uncertainty not previously considered in magnitude estimates of the 1811–1812 sequence based only on historical reports. The region covered by our simulation domain encompasses a large portion of the CUS centered on the NMSZ, including several major metropolitan areas. Based on our simulations, more than eight million people living and working near the NMSZ would experience potentially damaging ground motion and modified Mercalli intensities ranging from VI to VIII if a repeat of the 1811–1812 earthquakes occurred today. Moreover, the duration of strong ground shaking in the greater Memphis metropolitan area could last from 30 to more than 60 s, depending on the magnitude and epicenter.

Arkansas, Illinois, Kentucky, Missouri, Tennessee↗

USGS2022

Waveform signatures of earthquakes located close to the subducted Gorda Plate interface

Complex seismic velocity structure near the earthquake source can affect rupture dynamics and strongly modify the seismic waveforms recorded near the fault. Fault‐zone waves are commonly observed in continental crustal settings but are less clear in subduction zones due to the spatial separation between seismic stations and the plate boundary fault. We observed anomalously long duration S waves from earthquake clusters located near the interface of the subducted Gorda plate north of the Mendocino triple junction. In contrast, earthquakes located just a few kilometers below each cluster show impulsive S waves. A nodal array experiment was conducted around the Northern California Seismic Network station KCT for two months to investigate the origin of the complex S waves. Beamforming analysis shows that the S waves contain three arrivals that have different horizontal slownesses, which we term S 1, S 2, and S coda. Similar analysis on P waves also show two arrivals with different horizontal slownesses, which we term P 1 and P 2. P 1 and S 1 have larger horizontal slowness than P 2 and S 2, respectively, indicating that the phase pairs are body waves with different ray paths. Building upon a seismic refraction profile, we construct 1D velocity models and test different thicknesses and V P / V S ratios for the subducted oceanic crust. The arrival times and relative slownesses of P 1/ P 2 and S 1/ S 2 phases indicate that they are the direct and the Moho reflected phases, respectively. Their properties are consistent with a crustal thickness of ∼6 km and a moderate V P / V S ratio (∼1.8). The S coda is more difficult to characterize but has a clear dominant frequency that likely reflects the near‐source velocity and attenuation structure. Our study indicates that waveforms from earthquakes near the interface of the subducted slab can be used to infer detailed structural information about the plate‐boundary zone at seismogenic depths.

California↗

USGS2015

The Mw6.0 24 August 2014 South Napa earthquake

The M w 6.0 South Napa earthquake, which occurred at 10:20 UTC 24 August 2014 was the largest earthquake to strike the greater San Francisco Bay area since the M w 6.9 1989 Loma Prieta earthquake. The rupture from this right‐lateral earthquake propagated mostly unilaterally to the north and up‐dip, directing the strongest shaking toward the city of Napa, where peak ground accelerations (PGAs) between 45% g and 61% g were recorded and modified Mercalli intensities (MMIs) of VII–VIII were reported. Tectonic surface rupture with dextral slip of up to 46 cm was observed on a 12.5 km long segment, some of which was along a previously mapped strand of the West Napa fault system, although the rupture extended to the north of the mapped Quaternary strand. Modeling of seismic and geodetic data suggests an average coseismic slip of 50 cm, with a maximum slip of about 1 m at depths of 10–11 km. We observed up to 35 cm of afterslip along the surface trace in the week following the mainshock, primarily along the southern half of the surface rupture that experienced relatively little coseismic offset. Relocation of the sparse aftershock sequence suggests en echelon southwest‐ and northeast‐dipping fault planes, reflective of the complex fault geometry in this region. The Napa basin and historic and late Holocene alluvial flood deposits in downtown Napa amplified the ground motions there. Few ground failures were mapped, reflecting the dry season (as well as a persistent drought that had lowered the groundwater table) and the short duration of strong shaking in the epicentral area.

California↗

USGS2023

The 1886 Charleston, South Carolina, Earthquake: Relic railroad offset reveals rupture

In the absence of documented surface rupture during the 1 September 1886 Charleston earthquake, there has been considerable speculation about the location and mechanism of the causative fault. We use an inferred coseismic offset of the South Carolina Railroad and additional numerical constraints to develop an elastic deformation model—a west‐dipping fault following strands of two previously identified faults. The constraints are consistent with a blind rupture with 6.5 ± 0.3 m of dextral slip and 2 ± 0.5 m of reverse slip below 450 m depth. We propose that repeated slip on this fault has raised the Penholoway Marine Terrace >6 m since ∼770 ka. The inferred coseismic slip on the fault in an M w 7.3 earthquake is consistent with the distribution of damage in 1886.

South Carolina↗

USGS2014

Paleoseismology of the Southern Section of the Black Mountains and Southern Death Valley Fault Zones, Death Valley, United States

The Death Valley Fault System (DVFS) is part of the southern Walker Lane–eastern California shear zone. The normal Black Mountains Fault Zone (BMFZ) and the right-lateral Southern Death Valley Fault Zone (SDVFZ) are two components of the DVFS. Estimates of late Pleistocene-Holocene slip rates and recurrence intervals for these two fault zones are uncertain owing to poor relative age control. The BMFZ southernmost section (Section 1W) steps basinward and preserves multiple scarps in the Quaternary alluvial fans. We present optically stimulated luminescence (OSL) dates ranging from 27 to 4 ka of fluvial and eolian sand lenses interbedded with alluvial-fan deposits offset by the BMFZ. By cross-cutting relations, we infer that there were three separate ground-rupturing earthquakes on BMFZ Section 1W with vertical displacement between 5.5 m and 2.75 m. The slip-rate estimate is ∼0.2 to 1.8 mm/yr, with an earthquake recurrence interval of 4,500 to 2,000 years. Slip-per-event measurements indicate Mw 7.0 to 7.2 earthquakes. The 27–4-ka OSL-dated alluvial fans also overlie the putative Cinder Hill tephra layer. Cinder Hill is offset ∼213 m by SDVFZ, which yields a tentative slip rate of 1 to 8 mm/yr for the SDVFZ.

California;Nevada↗

USGS1978

A preliminary study of the Santa Barbara, California, earthquake of August 13, 1978, and its major aftershocks

The ML5.1 Santa Barbara earthquake of August 13, 1978 occurred at lat 34' 22.2'N., long 119 ? 43.0' 4 km south of Santa Barbara, Calif. at a depth of 12.5 km in the northeast Santa Barbara Channel, part of the western Transverse Ranges geomorphic-structural province. This part of the province is characterized by seismically active, east-trending reverse faults and rates of coastal uplift that have averaged up to about 10 m/1000 years over the last 45,000 years. No surface rupture was detected onshore. Subsurface rupture propagated northwest from the main shock toward Goleta, 15 km west of Santa Barbara, where a maximum acceleration of 0.44 g was measured at ground level and extensive minor damage occurred; only minor injuries were reported. A fairly well-constrained fault-plane solution of the main shock and distribution of the aftershocks indicate that left-reverse-oblique slip occurred on west-northwest-trending, north-dipping reverse faults; inadequate dip control precludes good correlation with any one of several mapped faults. Had the earthquake been larger and rupture propagated to the southeast or a greater distance to the northwest, it could have posed a hazard to oilfield operations. The fault-plane solution and aftershock pattern closely fit the model of regional deformation and the solution closely resembles those of five previously mapped events located within a 15-km radius.

California↗

USGS2005

Log of Trench 04A across the Hayward Fault at Tyson's Lagoon (Tule Pond), Fremont, Alameda County, California

This publication makes available a detailed trench log (sheets 1 and 2) of a 110-m trench we excavated in 2004 across a tectonic sag pond in the Hayward fault zone. Also included are revised stratigraphic unit descriptions from this fifth field season of subsurface investigation of the Hayward fault at Tyson's Lagoon (Tule Pond). Preliminary findings based on fieldwork done in 2000 have been published (Lienkaemper and others: data archive, 2002a; report, 2002b), as were the logs and data for 2001-2003 (Lienkaemper and others, 2003, L03). A continuous exposure of the geologic section across the entire pond made in 2004 (Fig. 1, 04A) has revealed some critical miscorrelations of units made in the original on-line version of L03, hence users of these earlier trench data should only use the 2005 revised version 2.0 of L03 for correlation purposes. Lienkaemper, Williams, and Sickler interpreted the geology and logged the trenches. Fumal did most of the trench photography. The Hayward fault is recognized to be among the most hazardous in the United States (Working Group on California Earthquake Probabilities, 2003). Establishing a chronology of prehistoric or paleoearthquakes is of immediate use in resolving the likelihood of future large earthquakes Hayward fault. This document makes available geologic evidence for historical and prehistoric surface-rupturing earthquakes preserved at the site. A second, formal report on our conclusions based on these data is in preparation.

Open-File Report↗

USGS2008

Conditional, time-dependent probabilities for segmented Type-A faults in the WGCEP UCERF 2

This appendix presents elastic-rebound-theory (ERT) motivated time-dependent probabilities, conditioned on the date of last earthquake, for the segmented type-A fault models of the 2007 Working Group on California Earthquake Probabilities (WGCEP). These probabilities are included as one option in the WGCEP?s Uniform California Earthquake Rupture Forecast 2 (UCERF 2), with the other options being time-independent Poisson probabilities and an ?Empirical? model based on observed seismicity rate changes. A more general discussion of the pros and cons of all methods for computing time-dependent probabilities, as well as the justification of those chosen for UCERF 2, are given in the main body of this report (and the 'Empirical' model is also discussed in Appendix M). What this appendix addresses is the computation of conditional, time-dependent probabilities when both single- and multi-segment ruptures are included in the model. Computing conditional probabilities is relatively straightforward when a fault is assumed to obey strict segmentation in the sense that no multi-segment ruptures occur (e.g., WGCEP (1988, 1990) or see Field (2007) for a review of all previous WGCEPs; from here we assume basic familiarity with conditional probability calculations). However, and as we?ll see below, the calculation is not straightforward when multi-segment ruptures are included, in essence because we are attempting to apply a point-process model to a non point process. The next section gives a review and evaluation of the single- and multi-segment rupture probability-calculation methods used in the most recent statewide forecast for California (WGCEP UCERF 1; Petersen et al., 2007). We then present results for the methodology adopted here for UCERF 2. We finish with a discussion of issues and possible alternative approaches that could be explored and perhaps applied in the future. A fault-by-fault comparison of UCERF 2 probabilities with those of previous studies is given in the main part of this report.

Open-File Report↗

USGS2008

Liquefaction hazard maps for three earthquake scenarios for the communities of San Jose, Campbell, Cupertino, Los Altos, Los Gatos, Milpitas, Mountain View, Palo Alto, Santa Clara, Saratoga, and Sunnyvale, Northern Santa Clara County, California

Maps showing the probability of surface manifestations of liquefaction in the northern Santa Clara Valley were prepared with liquefaction probability curves. The area includes the communities of San Jose, Campbell, Cupertino, Los Altos, Los Gatos Milpitas, Mountain View, Palo Alto, Santa Clara, Saratoga, and Sunnyvale. The probability curves were based on complementary cumulative frequency distributions of the liquefaction potential index (LPI) for surficial geologic units in the study area. LPI values were computed with extensive cone penetration test soundings. Maps were developed for three earthquake scenarios, an M7.8 on the San Andreas Fault comparable to the 1906 event, an M6.7 on the Hayward Fault comparable to the 1868 event, and an M6.9 on the Calaveras Fault. Ground motions were estimated with the Boore and Atkinson (2008) attenuation relation. Liquefaction is predicted for all three events in young Holocene levee deposits along the major creeks. Liquefaction probabilities are highest for the M7.8 earthquake, ranging from 0.33 to 0.37 if a 1.5-m deep water table is assumed, and 0.10 to 0.14 if a 5-m deep water table is assumed. Liquefaction probabilities of the other surficial geologic units are less than 0.05. Probabilities for the scenario earthquakes are generally consistent with observations during historical earthquakes.

Open-File Report↗

USGS2011

Liquefaction and other ground failures in Imperial County, California, from the April 4, 2010, El Mayor-Cucapah earthquake

The Colorado River Delta region of southern Imperial Valley, California, and Mexicali Valley, Baja California, is a tectonically dynamic area characterized by numerous active faults and frequent large seismic events. Significant earthquakes that have been accompanied by surface fault rupture and/or soil liquefaction occurred in this region in 1892 (M7.1), 1915 (M6.3; M7.1), 1930 (M5.7), 1940 (M6.9), 1950 (M5.4), 1957 (M5.2), 1968 (6.5), 1979 (6.4), 1980 (M6.1), 1981 (M5.8), and 1987 (M6.2; M6.8). Following this trend, the M7.2 El Mayor-Cucapah earthquake of April 4, 2010, ruptured approximately 120 kilometers along several known faults in Baja California. Liquefaction caused by the M7.2 El Mayor-Cucapah earthquake was widespread throughout the southern Imperial Valley but concentrated in the southwest corner of the valley, southwest of the city centers of Calexico and El Centro where ground motions were highest. Although there are few strong motion recordings in the very western part of the area, the recordings that do exist indicate that ground motions were on the order of 0.3 to 0.6g where the majority of liquefaction occurrences were found. More distant liquefaction occurrences, at Fites Road southwest of Brawley and along Rosita Canal northwest of Holtville were triggered where ground motions were about 0.2 g. Damage to roads was associated mainly with liquefaction of sandy river deposits beneath bridge approach fills, and in some cases liquefaction within the fills. Liquefaction damage to canal and drain levees was not always accompanied by vented sand, but the nature of the damage leads the authors to infer that liquefaction was involved in the majority of observed cases. Liquefaction-related damage to several public facilities - Calexico Waste Water Treatment Plant, Fig Lagoon levee system, and Sunbeam Lake Dam in particular - appears to be extensive. The cost to repair these facilities to prevent future liquefaction damage will likely be prohibitive. As such, it is likely that liquefaction will recur at these facilities during the next large earthquake in this area.

California↗

USGS1990

Digital recordings of aftershocks of the 17 October 1989 Loma Prieta, California, earthquake

After the 17 October 1989 Loma Prieta, central California, earthquake (291 00:04:15.25 UTC, M s =7.1), the U. S. Geological Survey recorded aftershocks at sites of seismologic and engineering interest. This report describes a seismic-waveform dataset collected from 17 October 1989 (291 UTC) to 14 March 1990 (073 UTC) with GEOS digital seismographs deployed from USGS offices in Menlo Park, California. It is a summary of field and data-playback information that is intended to facilitate use of the waveform data in seismologic and engineering studies. It includes station locations, instrumentation histories (trigger parameters, sensor parameters, clock corrections, etc.), listings of waveform records, preliminary seismicity listings, and information about data availability. Our principal research goal is to understand the influence of seismic-source and wave-propagation phenomena on damaging ground motions, and to use this knowledge to predict hazards from future earthquakes. Source processes encompass the spatial and temporal variations in the excitation of seismic waves at the fault. Wave-propagation processes include amplification and deamplification as seismic energy radiates away from the fault through rocks and soils of variable seismic properties. Since shallow geology at a site (upper tens to hundreds of meters) can exert a relatively great influence on damaging ground motions, it is useful to separate wave-propagation phenomena into whole-path and site parts. In studying these phenomena, aftershock waveform recordings can play an important role. Compared to main shocks, aftershocks are simple earthquakes and aftershock records tend to be relatively dominated by wave-propagation effects. Geometrically, since aftershocks are distributed over the fault zone, aftershock records should resemble part of the main-shock ground motion contributed by localized rupture. This observation forms the basis of the empirical-Green's-function method wherein main-shock ground motion is modeled by summing aftershock records. The Loma Prieta earthquake provided a rare opportunity that motivated the intensive aftershock-recording effort described in this report. In a seismically noisy urban environment like the San Francisco Bay area, such a large set of high quality seismic data would otherwise be unobtainable.

California↗

USGS1990

The Coalinga, California, earthquake of May 2, 1983

At 2342 G.m.t. May 2, 1983, a magnitude (ML) 6.7 earthquake occurred about 12 km northeast of the town of Coalinga, approximately halfway between Los Angeles and San Francisco. The shock was felt from Los Angeles to 200 km north of Sacramento and as far east as Las Vegas. Unlike other well-documented, major earthquakes in California in the 20th century, this event was not associated with any previously known or suspected active fault. Comprehensive geologic and geophysical investigations begun soon after the event have demonstrated the absence of a near-surface fault responsible for the earthquake. Instead, the earthquake was closely associated with a fault zone concealed beneath folds developed along the structural boundary between the Coast (Diablo) Ranges and the San Joaquin Valley.

California↗

USGS2016

Map of landslides triggered by the January 12, 2010, Haiti earthquake

The magnitude (M) 7.0 Haiti earthquake of January 12, 2010, triggered landslides throughout much of Haiti on the island of Hispaniola in the Caribbean Sea. The epicenter of the quake was located at 18.44°N., 72.57°W. at a depth of 13 kilometers (km) approximately 25 km southwest of the capital, Port-au-Prince. Although estimates vary widely, the most reliable surveys of casualties indicate that the earthquake caused 158,679 fatalities and more than 300,000 injuries. The U.S. Geological Survey compared publicly available satellite imagery acquired both before and after the earthquake and mapped 23,567 landslides that were triggered by the strong shaking. Our mapping from aerial photography and satellite imagery was augmented by field observations. Most of the landslides triggered by the earthquake were south of the Léogâne fault on the footwall and were fairly shallow falls and slides in weathered limestone (2–5 meters [m] thick) and volcanic rock and soil (generally <1 m thick). Landslides extended from the north to the south coasts of the southwestern peninsula (southwest of Port-au-Prince) and almost 60 km to the east and west of the epicenter. The highest concentration of landslides was on the steep limestone slopes of incised river valleys, but large numbers of landslides also occurred on gentler slopes in weathered volcanic rocks. Although some high landslide concentrations did occur near areas of maximum fault slip, the overall distribution of landslides appears to involve complex interactions between geology, topography, and strong shaking with limited spatial correlation between fault slip and landslides.

Scientific Investigations Map↗

USGS2020

Geometric controls on megathrust earthquakes

The role of subduction zone geometry in the nucleation and propagation of great-sized earthquake ruptures is an important topic for earthquake hazard, since knowing how big an earthquake can be on a given fault is fundamentally important. Past studies have shown subducting bathymetric features (e.g. ridges, fracture zones, seamount chains) may arrest a propagating rupture. Other studies have correlated the occurrence of great-sized earthquakes with flat megathrusts and homogenous stresses over large distances. It remains unclear, however, how subduction zone geometry and the potential for great-sized earthquakes ( M 8+) are quantifiably linked—or indeed whether they can be. Here, we examine the potential role of subduction zone geometry in limiting earthquake rupture by mapping the planarity of seismogenic zones in the Slab2 subduction zone geometry database. We build from the observation that historical great-sized earthquakes have preferentially occurred where the surrounding megathrust is broadly planar, and we use this relationship to search for geometrically similar features elsewhere in subduction zones worldwide. Assuming geometry exerts a primary control on earthquake propagation and termination, we estimate the potential size distribution of large ( M 7+) earthquakes and the maximum earthquake magnitude along global subduction faults based on geometrical features alone. Our results suggest that most subduction zones are capable of hosting great-sized earthquakes over much of their area. Many bathymetric features previously identified as barriers are indistinguishable from the surrounding megathrust from the perspective of slab curvature, meaning that they either do not play an important role in arresting earthquake rupture or that their influence on slab geometry at depth is not resolvable at the spatial scale of our subduction zone geometry models.

Geophysical Journal International↗