Earthquake Fault Research Articles

A Simplified Method for Rapid Estimation of Emergency Water Supply Needs after Earthquakes

Researchers are investigating the problem of estimating households with potable water service outages soon after an earthquake. Most of these modeling approaches are computationally intensive, have large proprietary data collection requirements or lack precision, making them unfeasible for rapid assessment, prioritization, and allocation of emergency water resources in large, complex disasters. This study proposes a new simplified analytical method—performed without proprietary water pipeline data—to estimate water supply needs after earthquakes, and a case study of its application in the HayWired earthquake scenario. In the HayWired scenario—a moment magnitude (Mw) 7.0 Hayward Fault earthquake in the San Francisco Bay Area, California (USA)—an analysis of potable water supply in two water utility districts was performed using the University of Colorado Water Network (CUWNet) model. In the case study, application of the simplified method extends these estimates of household water service outage to the nine counties adjacent to the San Francisco Bay, aggregated by a ~250 m2 (nine-arcsecond) grid. The study estimates about 1.38 million households (3.7 million residents) out of 7.6 million residents (2017, ambient, nighttime population) with potable water service outage soon after the earthquake—about an 8% increase from the HayWired scenario estimates.

Seismic behaviour of dams to near fault and far fault ground motions: A state of the art review

Dams are constructed across the river to confine the water and utilize it for various purposes such as hydroelectricity generation, flood control, irrigation, etc. Failure of dams causes huge loss to property and lives. Dams, designed to be built in high seismicity areas, are prone to damage due to intensive earthquake events. Strong ground motions recorded in the vicinity of fault planes are generally considered as near fault (or near source) ground motions. Near fault ground motions possess considerably different features which have high damage potential. In last few decades, a lot of studies have been conducted on the identification, characterization and simulation of pulse-type and non pulse-type ground motions. However, researchers have paid attention to the seismic safety assessment of dams under near fault and far fault ground motions since the last decade. In this context, this present study reports a state-of-the-art review on the seismic behaviour of various types of dams under different ground motions, based on available literature. This study also describes existing modelling techniques of the dam-reservoir-foundation system, failure modes, seismic analysis method and seismic response of different kinds of dams to near fault and far fault earthquakes. Finally, the study attempts to find the research gaps, which should be given proper attention in the future.

Multifractal Analysis of a Seismic Moment Distribution Obtained From InSAR Inversion.

Interferometric synthetic aperture radar (InSAR) interferograms contain valuable information about the fault systems hidden beneath the surface of the Earth. In a new approach, we aim to fit InSAR ground deformation data using a distribution of multiple seismic point sources whose parameters are found by a genetic algorithm. The resulting source distribution could provide another useful tool in solving the difficult problem of accurately mapping earthquake faults. We apply the algorithm to an ALOS‐2 InSAR interferogram and perform a multifractal analysis on the resulting distribution, finding that it exhibits multifractal properties. We report first results and discuss advantages and disadvantages of this approach.

Evaluation on Seismic Performance of Dual Steel Moment-Resisting Frame with Zipper Bracing System Compared to Chevron Bracing System against Near - Fault Earthquakes

In order to design seismic-resistant buildings, it is necessary to get comprehensive information about their behavior against the forces induced by earthquakes. Seismic design codes have been developed to meet the requirements of a safe and economical structure. According to the structural codes, the designed structures should not be damaged against light or moderate earthquakes so that the members should be had sufficient strength and safety while they should be a ductile complex with a proper structural configuration against severe earthquakes to dissipate the forces caused by ground motions. In the design of steel buildings, the use of moment-resisting frames in combination with braces is a seismic-resistant system. One of these systems is the dual steel moment-resisting frames with zipper braces. In this research, the seismic performance of the moment-resisting frame with the zipper brace system has been studied and its performance has been compared to the performance when the chevron bracing system is used. Three 4-story, 8-story, and 12-story buildings have been selected then they have been modeled by SAP2000 software, and finally, their seismic performances have been evaluated using time history analysis. The structural responses have been compared as comparing the relative displacement of the stories (story drift), the maximum displacement of the roof, and the formation of plastic hinges in the members. The results of the current study have been shown that using a zipper member has been decreased both overall displacement of the structure by about 10 to 30 percent, and also has been reduced the damage index of 4, 8, and 12-story structures by 27, 11, and 12 percent, respectively. The formation of plastic hinges has been directed from horizontal and vertical members toward diagonal members.

Fault Friction During Simulated Seismic Slip Pulses

AbstractTheoretical studies predict that during earthquake rupture faults slide at non‐constant slip velocity, however it is not clear which source time functions are compatible with the high velocity rheology of earthquake faults. Here we present results from high velocity friction experiments with non‐constant velocity history, employing a well‐known seismic source solution compatible with earthquake source kinematics. The evolution of friction in experiments shows a strong dependence on the applied slip history, and parameters relevant to the energetics of faulting scale with the impulsiveness of the applied slip function. When comparing constitutive models of strength against our experimental results we demonstrate that the evolution of fault strength is directly controlled by the temperature evolution on and off the fault. Flash heating predicts weakening behavior at short timescales, but at larger timescales strength is better predicted by a viscous creep rheology. We use a steady‐state slip pulse to test the compatibility of our strength measurements at imposed slip rate history with the stress predicted from elastodynamic equilibrium. Whilst some compatibility is observed, the strength evolution indicates that slip acceleration and deceleration might be more rapid than that imposed in our experiments.

Gravity gradient tensor analysis and its application to the Eastern Boundary Fault Zone of the Shonai Plain, Northeastern Japan

The Eastern Boundary Fault Zone of the Shonai Plain (EBFZSP), Northeast Japan is an active reverse fault zone, and its southern part is considered to have a high probability of earthquake occurrence. Also, the Aosawa Fault Zone (AFZ), categorised as a geological reverse fault, lies to the east of the EBFZSP by 3–10 km along strike, almost parallel to the EBFZSP. Therefore, the EBFZSP and its surrounding area are important in terms of their long-term earthquake occurrence potential and fault development history. After performing gravity measurements to compensate for the lack of coverage in the existing gravity database, a gravity gradient tensor analysis was applied around the EBFZSP to evaluate subsurface structural indices (dimensionality, dip angle, strike direction, and boundary indices). As a result, we conclude that the southern part of the EBFZSP appears to be at a relatively mature stage, which means that the part has both high two-dimensionality and boundary properties. On the other hand, the northern part of the EBFZSP appears to be relatively immature, which means that the northern part has both low two-dimensionality and boundary properties. A similar relationship was also found between the EBFZSP and the AFZ; that is, the former was immature, and the latter was mature. These features suggest that the EBFZSP developed from the south to the north, and was derived from the AFZ. We also found an area with high structural boundary indices and low two-dimensionality near some reported active folds beneath the Shonai Plain. A dip-angle index for a reverse-fault-like density structure showed results inconsistent with the dip angles observed on outcrop. To circumvent this contradiction, we propose the hypothesis that the EBFZSP, currently acting as a reverse fault, has a normal-fault-like density structure and we then attempt a phenomenological interpretation. The dip-angle index may be helpful only in simple situations.

Comparison of 3D Solid and Beam–Spring FE Modeling Approaches in the Evaluation of Buried Pipeline Behavior at a Strike-Slip Fault Crossing

Validated 3D solid finite element (FE) models offer an accurate performance of buried pipelines at earthquake faults. However, it is common to use a beam–spring model for the design of buried pipelines, and all the design guidelines are fitted to this modeling approach. Therefore, this study has focused on (1) the improvement of modeling techniques in the beam–spring FE modeling approach for the reproduction of the realistic performance of buried pipelines, and (2) the determination of an appropriate damage criterion for buried pipelines in beam–spring FE models. For this paper, after the verification of FE models by pull-out and lateral sliding tests, buried pipeline performance was evaluated at a strike-slip fault crossing using nonlinear beam–spring FE models and nonlinear 3D solid FE models. Material nonlinearity, contact nonlinearity, and geometrical nonlinearity effects were considered in all analyses. Based on the results, pressure and shear forces caused by fault movement and pipeline deformation around the high curvature zone cause local confinement of the soil, and soil stiffness around the high curvature zone locally increases. This increases the soil–pipe interaction forces on pipelines in high curvature zones. The beam–spring models and design guidelines, because of the uniform assumption of the soil spring stiffness along the pipe, do not consider this phenomenon. Therefore, to prevent the underestimation of forces on the pipeline, it is recommended to consider local increases in soil spring stiffness around the high curvature zone in beam–spring models. Moreover, drastic increases in the strain responses of the pipeline in the beam–spring model is a good criterion for a damage evaluation of the pipeline.

Numerical investigation of secondary-fault rupture propagation through sandy deposits

The increasing urban development in seismic-prone regions, in conjunction with the continuous construction of large-scale lifelines (i.e., road and railway networks, pipelines, etc.) has increased the risk of potential damages due to permanent displacements at the ground surface that can be caused by an earthquake fault rupture. Several recent earthquakes have revealed this risk. Therefore, the problem of fault rupture propagation of a single fault has been thoroughly investigated with field studies, as well as experimental tests and numerical models. Nevertheless, the presence of parallel or intersecting secondary fault ruptures is usually observed in the field due to stress redistributions and/or rock heterogeneities. The aim of the current study is to examine the rupture patterns and surface displacements caused by the contemporaneous rupture of a main fault and a perpendicular secondary fault. A three-dimensional numerical model has been developed utilizing the finite-element method in order to examine this complex phenomenon in sandy deposits. The soil behavior is represented quite accurately via an elastoplastic Mohr-Coulomb constitutive model with isotropic strain softening, which is initially validated with experimental results obtained by centrifuge tests in case of a single fault. Subsequently, a detailed parametric study has been performed, investigating different fault types and dip angles, as well as sandy layer thickness and material properties, to highlight various important aspects regarding the development and propagation of secondary fault ruptures and the resulting zones of excessive surface displacements.

Simultaneous Bayesian Estimation of Non‐Planar Fault Geometry and Spatially‐Variable Slip

AbstractLarge earthquakes are usually modeled with simple planar fault surfaces or a combination of several planar fault segments. However, in general, earthquakes occur on faults that are non‐planar and exhibit significant geometrical variations in both the along‐strike and down‐dip directions at all spatial scales. Mapping of surface fault ruptures and high‐resolution geodetic observations are increasingly revealing complex fault geometries near the surface and accurate locations of aftershocks often indicate geometrical complexities at depth. With better geodetic data and observations of fault ruptures, more details of complex fault geometries can be estimated resulting in more realistic fault models of large earthquakes. To address this topic, we here parametrize non‐planar fault geometries with a set of polynomial parameters that allow for both along‐strike and down‐dip variations in the fault geometry. Our methodology uses Bayesian inference to estimate the non‐planar fault parameters from geodetic data, yielding an ensemble of plausible models that characterize the uncertainties of the non‐planar fault geometry and the fault slip. The method is demonstrated using synthetic tests considering slip spatially distributed on a single continuous finite non‐planar fault surface with varying dip and strike angles both in the down‐dip and along‐strike directions. The results show that fault‐slip estimations can be biased when a simple planar fault geometry is assumed in presence of significant non‐planar geometrical variations. Our method can help to model earthquake fault sources in a more realistic way and may be extended to include multiple non‐planar fault segments or other geometrical fault complexities.

Hybrid broadband strong-motion simulation to investigate the near-source characteristics of the M6.5, 30 October 2016 Norcia, Italy earthquake

During the 2016–2017 Central Italy earthquake sequence, a series of moderate to large earthquakes M > 5 occurred near the Amatrice and Norcia towns. These events are recorded on a dense seismic network, providing relevant observational evidence of complex earthquakes in time and space. In this work, we used this substantial data set to study the ground-motion characteristics of the Norcia earthquake M6.5 on October 30, 2016, through a broadband ground-motion simulation. Three-component broadband seismograms are generated to cover the entire frequency band of engineering interest. Low and high frequencies are computed considering the heterogeneous slip rupture model of Scognamiglio et al. (2018) [1]. High frequencies are calculated using a stochastic approach including P, SV, and SH waves, while low frequencies are obtained through a forward simulation of the kinematic model at the various stations. To predict earthquake-induced ground-motions in the area, we adopted region-specific attenuation and source scaling parameters derived by Malagnini et al. (2011) [2]. Ground-motion parameters, including peak ground acceleration (PGA), peak ground velocity (PGV) and spectral amplitudes, are calculated at the selected sites adopting physics-based parameters to understand better the earthquake fault rupture, the wave propagation, and their impacts on the seismic hazard assessment in the region. We showed that combining the fault rupture history over the entire frequency spectrum of engineering interest, the attenuation characteristics of the seismic wave propagation and the properly defined site responses can improve the prediction of ground-motions and time histories, especially in near seismic sources.

Multiple Lines of Evidence for a Potentially Seismogenic Fault Along the Central-Apennine (Italy) Active Extensional Belt–An Unexpected Outcome of the MW6.5 Norcia 2016 Earthquake

The Apenninic chain, in central Italy, has been recently struck by the Norcia 2016 seismic sequence. Three mainshocks, in 2016, occurred on August 24 (MW6.0), October 26 (MW5.9) and October 30 (MW6.5) along well-known late Quaternary active WSW-dipping normal faults. Coseismic fractures and hypocentral seismicity distribution are mostly associated with failure along the Mt Vettore-Mt Bove (VBF) fault. Nevertheless, following the October 26 shock, the aftershock spatial distribution suggests the activation of a source not previously mapped beyond the northern tip of the VBF system. In this area, a remarkable seismicity rate was observed also during 2017 and 2018, the most energetic event being the April 10, 2018 (MW4.6) normal fault earthquake. In this paper, we advance the hypothesis that the Norcia seismic sequence activated a previously unknown seismogenic source. We constrain its geometry and seismogenic behavior by exploiting: 1) morphometric analysis of high-resolution topographic data; 2) field geologic- and morphotectonic evidence within the context of long-term deformation constraints; 3) 3D seismological validation of fault activity, and 4) Coulomb stress transfer modeling. Our results support the existence of distributed and subtle deformation along normal fault segments related to an immature structure, the Pievebovigliana fault (PBF). The fault strikes in NNW-SSE direction, dips to SW and is in right-lateral en echelon setting with the VBF system. Its activation has been highlighted by most of the seismicity observed in the sector. The geometry and location are compatible with volumes of enhanced stress identified by Coulomb stress-transfer computations. Its reconstructed length (at least 13 km) is compatible with the occurrence of MW≥6.0 earthquakes in a sector heretofore characterized by low seismic activity. The evidence for PBF is a new observation associated with the Norcia 2016 seismic sequence and is consistent with the overall tectonic setting of the area. Its existence implies a northward extent of the intra-Apennine extensional domain and should be considered to address seismic hazard assessments in central Italy.

Microstructural evolution of pseudotachylyte-bearing rocks during increasing temperatures: Evidence from rock-heating experiments

Pseudotachylyte are solidified melts that form from frictional heating on a fault plane during earthquakes and play an important role in the mechanism of faulting. Pseudotachylytes interact with mineralizing fluids and their textures are altered over long periods of time; consequently, determining seismic parameters by characterizing pseudotachylytes in the field remains challenging. In this study, we performed heating experiments on faulted pseudotachylyte-bearing cataclasites recovered from the Wenchuan Earthquake Fault Scientific Drilling Project-2 (WFSD-2) to constrain the formation of temperatures and microstructural evolution of the pseudotachylytes. These experiments revealed that melting occurred at 1100 °C, while microlites formed at 1100 °C and disappeared at 1500 °C, and metallic iron spherulites formed at 1300 °C. Fractures and cracks occurred in the pseudotachylytes after rapid cooling, implying an increase in pore volume that allowed for fluid infiltration and subsequent alteration. Because natural pseudotachylyte of the WFSD-2 shows the lack of microlite and the presence of metallic iron spherulites, our results imply that its formation was at temperature of 1300–1500 °C under water-deficient conditions.

First Use of Fragile Geologic Features to Set the Design Motions for a Major Existing Engineered Structure

ABSTRACTWe document the first use of fragile geologic features (FGFs) to set formal design earthquake motions for a major existing engineered structure. The safety evaluation earthquake (SEE) spectrum for the Clyde Dam, New Zealand (the mean 10,000 yr, ka, return period response spectrum) is developed in accordance with official guidelines and utilizes constraints provided by seven precariously balanced rocks (PBRs) located 2 km from the dam site and the local active Dunstan fault. The PBRs are located in the hanging wall of the fault. Deterministic PBR fragilities are estimated from field measurements of rock geometries and are the dynamic peak ground accelerations (PGAs) required for toppling. PBR fragility ages are modeled from B10e cosmogenic isotope exposure dating techniques and are in the range of 24–66 ka. The fragility ages are consistent with the PBRs having survived at least two large Dunstan fault earthquakes. We develop a PGA-based fragility distribution from all of the PBRs, which represents the cumulative toppling probability of a theoretical random PBR as a function of PGA. The fragility distribution is then used to eliminate logic-tree branches that produce PGA hazard curves that would topple the random PBR with a greater than 95% probability (i.e., less than 5% survival probability) over a time period of 24 ka (youngest PBR fragility age). The mean 10 ka spectrum of the remaining hazard estimates is then recommended as the SEE spectrum for the dam site. This SEE spectrum has a PGA of 0.55g, which is significantly reduced from the 0.96g obtained for a preliminary version of the SEE spectrum. The reduction is due to the combined effects of the PBR constraints and a substantial update of the probabilistic seismic hazard model. The study serves as an important proof-of-concept for future applications of FGFs in engineering design.

Characteristics of Seismicity in the Eagle Ford Shale Play, Southern Texas, Constrained by Earthquake Relocation and Centroid Moment Tensor Inversion

Abstract Analysis of earthquake locations and centroid moment tensors (CMTs) is critical in assessing seismogenic structures and connecting earthquakes to anthropogenic activities. The objective of this study was to gain insights into the seismotectonics of the Eagle Ford Shale play (EF), southern Texas, through relative relocation of earthquakes, assessment of CMT solutions, and investigation of the background stress field. Using Texas Seismological Network (TexNet) data from 2017 through 2019, we were able to relocate 326 earthquakes and obtain CMT solutions for 37 ML≥2.0 earthquakes. These earthquakes are located in the sedimentary basin and uppermost crust, with depths ranging from 2 to 10 km. The earthquake groups in the northeastern EF are linearly distributed along the Karnes fault zone, whereas the southern and western groups are spatially scattered around mapped or unmapped faults. CMT solutions identified 32 normal fault earthquakes and five strike-slip earthquakes. The orientation of the fault plane of most normal fault earthquakes is southwest–northeast, whereas the possible fault plane of the strike-slip fault is from north-northwest to south-southeast, which is roughly perpendicular to the normal faults. Normal and strike-slip faults in the EF are of high dip angles, with the dip angles of the most faults ranging from 60° to 80°. Stress inversion results show that the major orientation of maximum horizontal stress (SHmax) is southwest–northeast, with minor local stress-field rotations. We further estimated earthquake energy release in the EF region using moment magnitude from the CMT solutions, and the cumulative earthquake energy release curve reveals three notable increases in cumulative seismic moment, which occurred in January–July 2018 and January–March 2019, and May–August 2019. Whether these energy releases were caused by anthropogenic activities is a matter for further investigation.

Semi-probabilistic Method in Analysing Kendeng Fault Earthquake Hazard in Surabaya, East Java

Surabaya is one of the cities in Indonesia which is prone to earthquakes. This condition is caused by the megathrust zone located in southern Java. In addition, there is an active fault that passes through East Java, namely the Kendeng fault, which to be the source of underground earthquakes. The part of Kendeng Fault that is situated near Surabaya is classified as the Surabaya segment and Waru segment. Based on this condition, research was carried out to analyze the earthquake hazard caused by Kendeng Fault in Surabaya city. A semi-probabilistic method is used in this research, as it can calculate the Peak Ground Acceleration (PGA) and earthquake intensity by considering the range from the measurement point to every point on the fault. The PGA measurement is using the equation of attenuation function. USGS Vs30 data, East Java Province base map, and Surabaya geological map are the data that were used to support the research. The result of earthquake hazard analysis gives the highest ground acceleration potential region is located in the north-western Surabaya subdistricts, this includes Sambikerep and Lakarsantri subdistricts. The high value of PGA and earthquake intensity is strongly affected by the short distance to the earthquake source.

Infrastructure failure propagations and recovery strategies from an Alpine Fault earthquake scenario

While it is well established that community members should participate in resilience planning, participation with genuine decision-making power remains rare. We detail an end-to-end disaster impact reduction modelling framework for infrastructure networks, embedded within a scenario-based participatory approach. Utilising the AF8+ earthquake scenario, we simulate hazard exposure, asset failure and recovery of interdependent critical infrastructure networks. Quantifying service levels temporally offers insights into possible interdependent network performance and community disconnection from national networks, not apparent when studying each infrastructure in isolation. Sequencing participation enables feedbacks between integrated modelling and participants’ impact assessments. Shared ownership of modelling outputs advances stakeholders’ understanding of resilience measures, allowing real-time implementation, increasing community resilience. Readily understood by central government, this format may increase support and resourcing, if nationally significant. Finally, this method tested integrated modelling and impacts assessments, identifying and enabling improvements for both.

Garsela Fault and other NE-SW active faults along the southern part of Java Island

Most earthquake studies focus mainly on offshore subduction zones that often produce high-magnitude earthquakes. However, onshore active fault earthquakes also common to cause significant devastation, due to their proximity to human activity and their relatively shallow depth. Most of active faults in Java show a west-east (W-E) trending direction. However, the devastating Opak Fault ruptured in a NE-SW trend. Recent studies indicate that some shallow seismic clusters in Java cannot be associated with any known active fault traces. These seismic activities reported occurring in southern Garut, Cipamingkis (Sukabumi), Halimun-Salak Mountain (Bogor), and Grindulu in Pacitan. These seismic clusters show similar direction to the Opak Fault that ruptured an Mw6.4 earthquake in 2006 with thousands of fatalities. Here, we describe a brief review of the NE-SW trending active fault in the southern Garut area. Earthquake is a natural phenomenon with a repetitive mechanism. Therefore, we must be aware of the future hazard that has been demonstrated by recent seismic activities in this area.

Ambient noise Love wave attenuation tomography for the LASSIE array across the Los Angeles basin.

The Los Angeles basin is located within the North America-Pacific plate boundary and contains multiple earthquake faults that threaten greater Los Angeles. Seismic attenuation tomography has the potential to provide important constraints on wave propagation in the basin and to provide supplementary information on structure in the form of the distribution of anelastic properties. On the basis of the amplitude information from seismic interferometry from the linear LASSIE array in the Los Angeles basin, we apply station-triplet attenuation tomography to obtain a 2D depth profile for the attenuation structure of the uppermost 0.6 km. The array crosses four Quaternary faults, three of which are blind. The attenuation tomography resolves strong attenuation (shear attenuation Qs ~ 20) for the fault zones and is consistent with sharp boundaries across them.

Coupling of regional geophysics and local soil-structure models in the EQSIM fault-to-structure earthquake simulation framework

Accurate understanding and quantification of the risk to critical infrastructure posed by future large earthquakes continues to be a very challenging problem. Earthquake phenomena are quite complex and traditional approaches to predicting ground motions for future earthquake events have historically been empirically based whereby measured ground motion data from historical earthquakes are homogenized into a common data set and the ground motions for future postulated earthquakes are probabilistically derived based on the historical observations. This procedure has recognized significant limitations, principally due to the fact that earthquake ground motions tend to be dictated by the particular earthquake fault rupture and geologic conditions at a given site and are thus very site-specific. Historical earthquakes recorded at different locations are often only marginally representative. There has been strong and increasing interest in utilizing large-scale, physics-based regional simulations to advance the ability to accurately predict ground motions and associated infrastructure response. However, the computational requirements for simulations at frequencies of engineering interest have proven a major barrier to employing regional scale simulations. In a U.S. Department of Energy Exascale Computing Initiative project, the EQSIM application development is underway to create a framework for fault-to-structure simulations. This framework is being prepared to exploit emerging exascale platforms in order to overcome computational limitations. This article presents the essential methodology and computational workflow employed in EQSIM to couple regional-scale geophysics models with local soil-structure models to achieve a fully integrated, complete fault-to-structure simulation framework. The computational workflow, accuracy and performance of the coupling methodology are illustrated through example fault-to-structure simulations.

Reassessing Eastern Mediterranean Tectonics and Earthquake Hazard From the 365 CE Earthquake

AbstractThe hallmark of great earthquakes in the Mediterranean is the 21 July 365 CE earthquake and tsunami that destroyed cities and killed thousands of people throughout the Eastern Mediterranean. This event is intriguing because most Mediterranean subduction forearcs exhibit pervasive crustal extension and minimal definitive evidence exists for great subduction megathrust earthquakes, consistent with weak seismic coupling. This conundrum has led many to favor rupture of a previously unrecognized upper plate splay fault south of Crete in an M w 8.3–8.5 earthquake, uplifting a Cretan Holocene paleoshoreline by up to 9 m. Similar source mechanisms have been adapted for the region, which are commonly used for seismic and tsunami hazard estimation. We present an alternative model for Holocene paleoshoreline uplift and the 365 CE tsunami that centers on known active normal fault systems offshore of western and southwestern Crete. We use new and published radiocarbon dates and historical records to show that uplift of the Cretan paleoshoreline likely occurred during two or more earthquakes within 2–3 centuries. Visco‐elastic dislocation modeling demonstrates that the rupture of these normal faults fits observed data as well as reverse fault models but requires reduced slip and lower cumulative earthquake energy release (∼M w 7.9). Tsunami modeling shows that normal‐fault ruptures produce strong tsunamis that better match historical reports than a hypothetical reverse fault. Our findings collectively favor the interpretation that damaging earthquakes and tsunamis in the Eastern Mediterranean can originate on normal faults, highlighting the potential hazard from tsunamigenic upper plate normal fault earthquakes.