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Adding fins or metal foam to phase change units can effectively enhance the heat storage efficiency of thermal energy storage (TES) tanks, thereby improving the reliability of TES tanks in coordinating renewable energy supply and demand. In this study, an experimental TES tank platform was designed and constructed to investigate how the addition of straight fins, metal foam, and straight fin/metal foam composite materials to paraffin affects the temperature response during the heat storage process. High-temperature water was selected as the heat transfer fluid (HTF) and injected from the top into the TES tank at the same paraffin fill level, and T-type thermocouples were arranged along the central axis of the phase change unit. TES tanks filled with either pure paraffin or composite phase change materials were tested by varying the HTF inlet temperature and velocity, and temperature response data were captured and recorded using a KEYSIGHT DAQ970A data logger. The results indicated that increasing the HTF inlet temperature significantly enhanced the heat storage rate while increasing the HTF inlet velocity had varying effects on different phase change units. A comprehensive analysis suggested that an inlet velocity of 1.3 m3/h (from a range of 0.8–1.8 m3/h) was reasonable. The addition of enhancement measures improved the temperature drift phenomena and effectively increased the temperature response rates and distribution uniformity. Moreover, the straight fin/metal foam composite material exhibited the best performance.

A major (MW7.9) intraplate earthquake ruptured the Pacific plate seaward of the Alaska subduction zone near Kodiak Island on 23 January 2018. The aftershock seismicity is diffuse, with both NNW‐ and ENE‐trending distributions, while long‐period point source moment tensors have near‐horizontal compressional and tensional principal strain axes and significant non‐double‐couple components. Backprojections from three large‐aperture networks indicate sources of short‐period radiation not aligned with the best double‐couple fault planes. A suite of finite‐fault rupture models with one to four faults was considered, and a four‐fault model, dominated by right‐lateral slip on an SSE trending, westward‐dipping fault, is compatible with most seismic, GPS, and tsunami data. However, the precise geometry, timing, and slip distribution of the complex set of faults is not well resolved. The sequence appears to be the result of intraplate stresses influenced by slab pull, the 1964 Alaska earthquake, and collision of the Yakutat terrane in northeastern Alaska. On 23 January 2018 a very large earthquake, with magnitude 7.8, ruptured in the Pacific plate southwest of the Alaskan subduction zone. There are multiple indications of complex faulting for this event: The point source moment tensor is not consistent with a single fault rupture; the aftershock distribution is diffuse, with nearly orthogonal trends in seismicity; the aftershock mechanisms are diverse; backprojections of short‐period seismic waves show complex patterns of high‐frequency energy release not on a single plane; and teleseismic waveforms are complex. Inversions of the teleseismic signals for a variety of models with from one to four different faults being allowed provide slip models that are used to predict regional GPS observations from Alaska along with deepwater tsunami recordings from seafloor pressure sensors at Deep‐ocean Assessment and Reporting of Tsunamis (DART) stations. The primary rupture occurred on a fault trending SSE, dipping to the west, and several nearly perpendicular faults appear to have ruptured as well, but the limited spatial extent of the rupture makes it difficult to resolve the details of the faulting. Several faults ruptured the Pacific plate seaward of Kodiak Island; most slip was on a southward‐trending right‐lateral strike‐slip faultTeleseismic body waves, aftershock distribution, regional GPS offsets, and tsunami observations are used to constrain the complex faultingThe principal stress directions are influenced by slab pull, the 1964 Alaska earthquake deformation, and collision of the Yakutat terrane

Wave climate plays an important role in the air-sea interaction over marginal seas. Extreme wave height provides fundamental information for various ocean engineering practices, such as hazard mitigation, coastal structure design, and risk assessment. In this paper, we implement a third generation wave model and conduct a high-resolution wave hindcast over the East China Sea to reconstruct a 15-year wave field from 1988 to 2002 for derivation of monthly mean wave parameters and analysis of extreme wave conditions. The numerical results of the wave field are validated through comparison with satellite altimetry measurements, low-resolution reanalysis, and the ocean wave buoy record. The monthly averaged wave height and wave period show seasonal variation and refined spatial patterns of surface waves in the East China Sea. The climatological significant wave height and mean wave period decrease from the open ocean in the southeast toward the continental area in the northwest, with the pattern generally following the bathymetry. Extreme analysis on the significant wave height at the buoy station indicates the hindcast data underestimate the extreme values relative to the observations. The spatial pattern of extreme wave height shows single peak emerges at the southwest of Ryukyu Island although a wind forcing with multi-core structure at the extreme is applied.

The 13 November 2016 Kaikoura, New Zealand, Mw7.8 earthquake ruptured multiple crustal faults in the transpressional Marlborough and North Canterbury tectonic domains of northeastern South Island. The Hikurangi trench and underthrust Pacific slab terminate in the region south of Kaikoura, as the subdution zone transitions to the Alpine fault strike‐slip regime. It is difficult to establish whether any coseismic slip occurred on the megathrust from on‐land observations. The rupture generated a tsunami well recorded at tide gauges along the eastern coasts and in Chatham Islands, including a ~4 m crest‐to‐trough signal at Kaikoura where coastal uplift was about 1 m, and at multiple gauges in Wellington Harbor. Iterative modeling of teleseismic body waves and the regional water‐level recordings establishes that two regions of seafloor motion produced the tsunami, including an Mw~7.6 rupture on the megathrust below Kaikoura and comparable size transpressional crustal faulting extending offshore near Cook Strait. The 2016 Kaikoura earthquake produced tsunami signals that indicate sizeable seafloor deformation in addition to onshore surface rupturesIterative modeling of teleseismic Pand SHwaves and regional tide and wave gauge recordings indicates two regions of seafloor deformationTsunami excitation involved oblique thrusting on the southern Hikurangi megathrust and offshore extension of transpressional faults

In this study, a numerical simulation was employed to assess the heat storage and exothermic behaviour of a phase change unit with different heat flow channel configurations, height-to-diameter ratios, inlet flow rates, and addition of different rib structural parameters. Thus, we aimed to explore the heat storage and exothermic behaviour of the phase change accumulator under changes to the heat transfer medium flow field. By analysing the variation in the velocity and temperature fields of the heat transfer medium and using the field synergy principle, the structure of the cylindrical phase change accumulator was optimised, and the liquid fraction, field synergy angle, and Nunumber in different structures were compared. The results revealed that the H-type heat exchanger flow channel could effectively improve the heat exchanger field synergy and increase the heat storage rate by 6.3 %. Increasing the inlet flow velocity could accelerate the heat storage rate; however, the flow velocity caused the flow field synergy to fluctuate and the heat storage efficiency to increase gradually. On increasing the height-to-diameter ratio, the heat exchanger field synergy ‘increased first and then decreased’, reaching the optimal heat transfer effect when D = 1.932. Under the heat storage and release condition, the straight rib heat transfer was superior to that for the ring rib. The change in the built-in straight rib length played a dominant role in the heat storage rate. Accordingly, for optimal heat transfer, the rib length was set to >45 mm, rib thickness to 1.5–2 mm, and number of ribs to 10. Meanwhile, the heat release efficiency initially increased as the length of the external straight rib increased and subsequently decreased. For optimal heat transfer, the rib length was set between 15 and 25 mm, rib thickness to >1.5 mm, and the number of ribs to >10 ribs. Therefore, we determined the ranges of structural parameters that would provide appropriate references for this phase change accumulator in fields such as thermal energy storage and waste heat recovery.

A great earthquake struck the Semidi segment of the plate boundary along the Alaska Peninsula on 29 July 2021, re‐rupturing part of the 1938 rupture zone. The 2021 MW8.2 Chignik earthquake occurred just northeast of the 22 July 2020 MW7.8 Simeonof earthquake, with little slip overlap. Analysis of teleseismic Pand SHwaves, regional Global Navigation Satellite System (GNSS) displacements, and near‐field and far‐field tsunami observations provides a good resolution of the 2021 rupture process. During ∼60‐s long faulting, the slip was nonuniformly distributed along the megathrust over depths from 32 to 40 km, with up to ∼12.9‐m slip in an ∼170‐km‐long patch. The 40–45 km down‐dip limit of slip is well constrained by GNSS observations along the Alaska Peninsula. Tsunami observations preclude significant slip from extending to depths <25 km, confining all coseismic slip to beneath the shallow continental shelf. Most aftershocks locate seaward of the large‐slip zones, with a concentration of activity up‐dip of the deeper southwestern slip zone. Some localized aftershock patches locate beneath the continental slope. The surface‐wave magnitude MSof 8.1 for the 2021 earthquake is smaller than MS= 8.3–8.4 for the 1938 event. Seismic and tsunami data indicate that slip in 1938 was concentrated in the eastern region of its aftershock zone, extending beyond the Semidi Islands, where the 2021 event did not rupture. The Pacific plate underthrusts the North American plate along the Alaska‐Aleutian subduction zone producing great earthquakes along most of the plate boundary. The region, that ruptured in 1938, hosted another great earthquake with magnitude 8.2 on 29 July 2021 offshore of Chignik, adjacent to a magnitude 7.8 event in 2020 beneath the Shumagin Islands. Using seismic wave recordings, Global Navigation Satellite System static displacements, and tsunami wave recordings at regional and distant locations, we determine the space‐time evolution of slip during the 2021 rupture process. The rupture extended northeastward ∼170 km, ending just short of the Semidi Islands. The slip is concentrated on the megathrust, from 32‐km to 40‐km deep. Shallow slip at depths <25 km is precluded by the tsunami observations, confining all rupture to beneath the shallow continental shelf. Most aftershocks are up‐dip of the large‐slip regions with a concentration in the shallow region of the southwestern rupture zone. Comparisons of observations and rupture models with the 1938 event indicate distinct slip distributions and seismic energy release, with the 1938 event being somewhat larger and extending further northeast than the 2021 rupture. This provides strong evidence that the 2021 event is not a simple repeat failure of the 1938 rupture. The slip distribution of the 2021 Chignik MW8.2 earthquake is constrained by joint analysis of seismic, geodetic, and tsunami recordingsDuring the ∼60‐s long rupture, patchy slip of up to 12.9 m occurred at depths of 32–40 km on the megathrust below the continental shelfThe 2021 slip pattern differs from the 1938 MW8.2 rupture, with larger slip in the west and no slip in the easternmost 1938 rupture zone The slip distribution of the 2021 Chignik MW8.2 earthquake is constrained by joint analysis of seismic, geodetic, and tsunami recordings During the ∼60‐s long rupture, patchy slip of up to 12.9 m occurred at depths of 32–40 km on the megathrust below the continental shelf The 2021 slip pattern differs from the 1938 MW8.2 rupture, with larger slip in the west and no slip in the easternmost 1938 rupture zone

The Shumagin seismic gap along the Alaska Peninsula experienced a major, MW7.8, interplate thrust earthquake on 22 July 2020. Several available finite‐fault inversions indicate patchy slip of up to 4 m at 8–48 km depth. There are differences among the models in peak slip and absolute placement of slip on the plate boundary, resulting from differences in data distributions, model parameterizations, and inversion algorithms. Two representative slip models obtained from inversions of large seismic and geodetic data sets produce very different tsunami predictions at tide gauges and deep‐water pressure sensors (DART stations), despite having only secondary differences in slip distribution. This is found to be the result of the acute sensitivity of the tsunami excitation for rupture below the continental shelf in proximity to an abrupt shelf break. Iteratively perturbing seismic and geodetic inversions by constraining fault model extent along dip and strike, we obtain an optimal rupture model compatible with teleseismic Pand SHwaves, regional three‐component broadband and strong‐motion seismic recordings, hr‐GNSS time series and static offsets, as well as tsunami recordings at DART stations and regional and remote tide gauges. Slip is tightly bounded between 25 and 40 km depth, the up‐dip limit of slip in the earthquake is resolved to be well‐inland of the shelf break, and the rupture extent along strike is well‐constrained. The coseismic slip increased Coulomb stress on the shallow plate boundary extending to the trench, but the frictional behavior of the megathrust below the continental slope remains uncertain. Several studies on the 22 July 2020 MW7.8 thrust event have included finite‐fault inversions, yielding generally consistent slip models. However, none of these studies have fully considered the seismic and geodetic data together with the tsunami measurements at tide gauges and deep‐water pressure sensors. We select two representative slip models obtained from prior seismic and geodetic inversions for tsunami modeling and find that they give distinct tsunami predictions despite having only a minor shift of slip by ∼20 km relative to shelf break. Large differences in tsunami excitation occur when seafloor deformation extends to the continental slope under deeper water. We perform iterative inversion of seismic and geodetic observations and forward modeling of tsunami signals to obtain an optimal slip model compatible with teleseismic waves, regional seismic recordings, hr‐GNSS time series and static offsets, along with tsunami recordings at DARTs and tide gauges. Precise placement of the slip distribution beneath the continental shelf controls the strength and timing of seaward tsunamis, with waveforms varying nonlinearly with seafloor deformation extending across the shelf break. The earthquake increased Coulomb stress on the shallow megathrust, but uncertainty in the shallow frictional behavior leaves it unclear whether a future large event can occur there. Published finite‐fault models for the 2020 MW7.8 earthquake predict varying tsunami signals despite having similar slip patternsThe tsunami excitation is very sensitive to the absolute placement of slip relative to the shelf break and along strikeIteration of slip inversion parameters and tsunami predictions optimizes the model to fit all data well with slip only beneath the shelf Published finite‐fault models for the 2020 MW7.8 earthquake predict varying tsunami signals despite having similar slip patterns The tsunami excitation is very sensitive to the absolute placement of slip relative to the shelf break and along strike Iteration of slip inversion parameters and tsunami predictions optimizes the model to fit all data well with slip only beneath the shelf

The 1 April 2014 Iquique Mw8.1 earthquake ruptured a segment of the megathrust fault offshore of northern Chile and generated a moderate‐size tsunami across the Pacific. Tide gauges in Hawaii recorded over 1 m of wave height despite the long distance from the source and position away from the main radiated energy lobe. Inversion of global teleseismic body waves combined with forward modeling of the tsunami at four near‐field DART stations arrives iteratively at a self‐consistent finite‐fault model with very compact dimensions. The slip distribution produces a NNE‐SSW trending seafloor uplift patch that enhances the tsunami directionality in the WNW, resulting in good matches to observed DART and tide gauge records around the Hawaiian Islands. The relatively large waves at selected locations in Hawaii can be attributed to a combination of the spatial slip distribution and the resulting short‐period waves that triggered localized resonance over the insular shelves. This event highlights the importance of characterizing detailed slip distributions in analysis or forecasting of tsunamis even for a compact source. A finite‐fault rupture model is found to match global seismic and near‐field tsunami observationsFar‐field tsunami surges around the Hawaiian Islands provide independent validationDetailed slip distribution influences tsunami waves even for a compact source

The 25 October 2010 Mentawai tsunami earthquake (Mw7.8) ruptured the shallow portion of the Sunda megathrust seaward of the Mentawai Islands, offshore of Sumatra, Indonesia, generating a strong tsunami that took 509 lives. The rupture zone was updip of those of the 12 September 2007 Mw8.5 and 7.9 underthrusting earthquakes. High‐rate (1 s sampling) GPS instruments of the Sumatra GPS Array network deployed on the Mentawai Islands and Sumatra mainland recorded time‐varying and static ground displacements at epicentral distances from 49 to 322 km. Azimuthally distributed tsunami recordings from two deepwater sensors and two tide gauges that have local high‐resolution bathymetric information provide additional constraints on the source process. Finite‐fault rupture models, obtained by joint inversion of the high‐rate (hr)‐GPS time series and numerous teleseismic broadband Pand Swave seismograms together with iterative forward modeling of the tsunami recordings, indicate rupture propagation ~50 km up dip and ~100 km northwest along strike from the hypocenter, with a rupture velocity of ~1.8 km/s. Subregions with large slip extend from 7 to 10 km depth ~80 km northwest from the hypocenter with a maximum slip of 8 m and from ~5 km depth to beneath thin horizontal sedimentary layers beyond the prism deformation front for ~100 km along strike, with a localized region having >15 m of slip. The seismic moment is 7.2 × 1020N m. The rupture model indicates that local heterogeneities in the shallow megathrust can accumulate strain that allows some regions near the toe of accretionary prisms to fail in tsunami earthquakes. The 2010 Mentawai tsunami earthquake ruptured to the trenchRupture model is obtained by modeling hr‐GPS, seismic, and tsunami dataPatchy slip at the toe of the trench indicates local strain accumulation

The 2011 Tohoku tsunami devastated the northeastern Japan coasts and caused localized damage to coastal infrastructure across the Pacific. The tsunami resulted in strong currents around the Hawaiian Islands that led to closure of harbors and marinas for up to 38 h after its arrival. We utilize a nonhydrostatic model to reconstruct the tsunami event from the seismic source for elucidation of the physical processes and inference of the coastal hazards. A number of tide gauges, bottom pressure sensors, and ADCPs provided point measurements for validation and assessment of the model results in Hawaii. Spectral analysis of the computed surface elevation and current reveals complex flow patterns due to multiscale resonance. Standing waves with 33–75 min period develop along the island chains, while oscillations of 27 min or shorter are primarily confined to an island or an island group with interconnected shelves. Standing edge waves with periods 16 min or shorter, which are able to form nodes on the reefs and inside harbors, are the main driving force of the observed coastal currents. Resonance and constructive interference of the oscillation modes provide an explanation of the impacts observed in Hawaii with implications for emergency management in Pacific island communities. Model reproduces measured surface elevations and currents in tropical islandsResonance modes between 6.5 to 75 min along the Hawaiian IslandsStrong tsunami currents over reefs from standing waves below 16 min period

The 17 July 2017 Komandorsky Islands MW7.8 earthquake involved arc‐parallel right‐lateral patchy strike‐slip faulting along ~400 km of the Bering Fracture Zone (BFZ) in the westernmost Aleutian Islands back arc. The large size of the earthquake indicates that the BFZ serves regionally as the primary plate boundary extending from the Near Islands to Kamchatka, with the fore‐arc Komandorsky Sliver translating rapidly parallel to the Aleutian Trench. The slip distribution is determined by analysis of seismic, tsunami, and geodetic observations. Fault displacements of 4 to 8.5 m, mostly in the upper 15 km, but with localized extension to 20 to 30 km depth along a ~100 km long segment of the BFZ, are comparable to the possible slip deficit since the last major earthquakes in this region in 1849 and 1858, given an estimated 5.1 cm/yr rate between the Komandorsky Sliver and the Bering Plate. A large earthquake struck the westernmost portion of the Aleutian Island arc on 17 July 2017. In this region the Pacific plate is moving relative to the North American plate parallel to the plate boundary, with no convergence. As a result the plate motion is accommodated on a strike‐slip fault in the upper plate, located along the Bering Fracture Zone. The earthquake produced slip and aftershocks along a 400 km long stretch of the Bering Fracture Zone in a magnitude 7.8 earthquake. The slip distribution and time history are determined by modeling seismic, geodetic, and tsunami data. The event is comparable in length and seismic moment to the 1906 San Francisco earthquake on the San Andreas Fault. The 17 July 2017 Komandorsky Islands earthquake ruptured the back‐arc Bering Fracture Zone between the Komandorsky Sliver and Bering PlateRight‐lateral strike‐slip faulting with patchy slip extended ~400 km along strike including a southeastern large‐slip patch ~100 km longThe slip was sufficient to release strain accumulated since the last rupture in 1858; the BFZ is the primary plate boundary in the region

On 8 September 2017, a great (Mw8.2) normal faulting earthquake ruptured within the subducting Cocos Plate ~70 km landward from the Middle American Trench beneath the Tehuantepec gap. Iterative inversion and modeling of teleseismic and tsunami data and prediction of GPS displacements indicate that the steeply dipping rupture extended ~180 km to the northwest along strike toward the Oaxaca coast and from ~30 to 70 km in depth, with peak slip of ~13 m. The rupture likely broke through the entire lithosphere of the young subducted slab in response to downdip slab pull. The plate boundary region between the trench and the fault intersection with the megathrust appears to be frictionally coupled, influencing location of the detachment. Comparisons of the broadband body wave magnitude (mB) and moment‐scaled radiated energy (ER/M0) establish that intraslab earthquakes tend to be more energetic than interplate events, accounting for strong ground shaking observed for the 2017 event. A large earthquake ruptured in the subducting Cocos Plate that underthrusts Mexico and Central America offshore of Chiapas, in southern Mexico. Analysis of seismic waves, deepwater tsunami recordings, and onshore geodetic displacements establishes that the rupture was on a steeply dipping fault plane and that the slip extended across the entire underthrust lithosphere, partially detaching the deeper slab. The event is located beneath the continental shelf, and there is a narrow zone of the megathrust from the Middle American Trench to where this event reached the plate boundary that appears to have frictional coupling, which likely influenced the location of the slab detachment. The event radiated stronger short‐period seismic waves than typical of comparable size events on subduction zone plate boundaries, producing severe damage in Oaxaca and Chiapas. The 2017 Mw8.2 Chiapas normal faulting earthquake beneath the Tehuantepec gap involved lithospheric‐transecting rupture of the thin Cocos slabSeismic, tsunami, and GPS data indicate that the rupture extended ~100 km unilaterally to the northwest along strike and from ~30 to 70 km in depthRelative to megathrust earthquakes, subduction zone intraslab faulting is more energetic, resulting in strong ground shaking for the 2017 event

Tsunami observations play an important role in resolving offshore earthquake slip distributions. Nondispersive shallow‐water models are often used with a static initial sea surface pulse derived from seafloor deformation in computation of tsunami Green's functions. We compare this conventional approach with more advanced techniques based on a dispersive model with a static initial sea surface pulse and with the surface waves generated from kinematic seafloor deformation. These three sets of tsunami Green's functions are implemented in finite‐fault inversions with and without seismic and geodetic data for the 2010 Mentawai Mw7.8 tsunami earthquake. Seafloor excitation and wave dispersion produce more spread‐out waveforms in the Green's functions leading to larger slip with more compact distribution through the inversions. The fit to the recorded tsunami and the deduced seismic moment, which reflects the displaced water volume, are relatively insensitive to the approach used for computing Green's functions. Modeling of tsunami generation from seafloor deformation leads to depth‐dependent attenuation and spreading of initial waves at the sourceDispersion complements depth‐dependent tsunami excitation through lagging of short‐period components during trans‐oceanic propagationIncluding depth‐dependent tsunami excitation and dispersion in Green's functions produces larger and more concentrated slip through inversion