Magnitude Scale Research Articles

Recalibration of the Local Magnitude (ML) Scale for Earthquakes in the Yellowstone Volcanic Region

ABSTRACT The Yellowstone volcanic region is one of the most seismically active areas in the western United States. Assigning magnitudes (M) to Yellowstone earthquakes is a critical component of monitoring this geologically dynamic zone. The University of Utah Seismograph Stations (UUSS) has assigned M to 46,767 earthquakes in Yellowstone that occurred between 1 January 1984 and 31 December 2020. Here, we recalibrate the local magnitude (ML) distance and station corrections for the Yellowstone volcanic region. This revision takes advantage of the large catalog of earthquakes and an increase in broadband stations installed by the UUSS since the last ML update in 2007. Using a nonparametric method, we invert 7728 high-quality, analyst-reviewed amplitude measurements from 1383 spatially distributed earthquakes for 39 distance corrections and 20 station corrections. The inversion is constrained with four moment magnitude (Mw) values determined from time-domain inversion of regional-distance broadband waveforms by the UUSS. Overall, the new distance corrections indicate relatively high attenuation of amplitudes with distance. The distance corrections decrease with hypocentral distance from 3 km to a local minimum at 80 km, rise to a broad peak at 110 km, and then decrease again out to 180 km. The broad peak may result from superposition of direct arrivals with near-critical Moho reflections. Our ML inversion doubles the number of stations with ML corrections in and near the Yellowstone volcanic region. We estimate that the additional station corrections will nearly triple the number of Yellowstone earthquakes that can be assigned an ML. The new ML distance and station corrections will also reduce uncertainties in the mean MLs for Yellowstone earthquakes. The new MLs are ∼0.07 (±0.18) magnitude units smaller than the previous MLs and have better agreement with 12 Mws (3.15–4.49) determined by the UUSS and Saint Louis University.

Impact of the SARS-CoV-2 pandemic on routine immunisation services: evidence of disruption and recovery from 170 countries and territories

SummaryBackgroundThe SARS-CoV-2 pandemic has revealed the vulnerability of immunisation systems worldwide, although the scale of these disruptions has not been described at a global level. This study aims to assess the impact of COVID-19 on routine immunisation using triangulated data from global, country-based, and individual-reported sources obtained during the pandemic period.MethodsThis report synthesised data from 170 countries and territories. Data sources included administered vaccine-dose data from January to December, 2019, and January to December, 2020, WHO regional office reports, and a WHO-led pulse survey administered in April, 2020, and June, 2020. Results were expressed as frequencies and proportions of respondents or reporting countries. Data on vaccine doses administered were weighted by the population of surviving infants per country.FindingsA decline in the number of administered doses of diphtheria–pertussis–tetanus-containing vaccine (DTP3) and first dose of measles-containing vaccine (MCV1) in the first half of 2020 was noted. The lowest number of vaccine doses administered was observed in April, 2020, when 33% fewer DTP3 doses were administered globally, ranging from 9% in the WHO African region to 57% in the South-East Asia region. Recovery of vaccinations began by June, 2020, and continued into late 2020. WHO regional offices reported substantial disruption to routine vaccination sessions in April, 2020, related to interrupted vaccination demand and supply, including reduced availability of the health workforce. Pulse survey analysis revealed that 45 (69%) of 65 countries showed disruption in outreach services compared with 27 (44%) of 62 countries with disrupted fixed-post immunisation services.InterpretationThe marked magnitude and global scale of immunisation disruption evokes the dangers of vaccine-preventable disease outbreaks in the future. Trends indicating partial resumption of services highlight the urgent need for ongoing assessment of recovery, catch-up vaccination strategy implementation for vulnerable populations, and ensuring vaccine coverage equity and health system resilience.FundingUS Agency for International Development.

Interactions of umami with the four other basic tastes in equi-intense aqueous solutions

Previous research has shown that the addition of equi-intense concentrations of taste compounds leads to mixture suppression, with sweetness being the least suppressed taste while being the strongest suppressor of the other taste stimuli. However, perceived intensity of umami (savoury taste) within complex mixtures is less defined. Since maintaining savoury taste of foods at reduced salt levels is a growing need, this study investigated the role of umami in complex taste systems. Initially the concentrations of single tastants were adjusted until a trained sensory panel rated them as equi-intense using general labelled magnitude scales (gLMS). In order to evaluate the impact of umami taste on other tastes, and vice versa, three sample sets were prepared as binary and quinary systems. The first two sets utilised monosodium glutamate (MSG) as the umami tastant; one set without balancing the sodium level in MSG and another set accounting for it by the addition of sodium at an equivalent molarity. The third set used monopotassium L-glutamate monohydrate (MPG) as the source of umami to overcome the confounding influence of sodium. All samples were rated by trained sensory panellists. The results of the three studies conclude that umami taste does not enhance or suppress the perception of any other taste in binary aqueous taste systems (p > 0.05); whereas sweet, salty, sour and bitter significantly suppress the perception of umami in both binary and quinary systems (p < 0.05). Where glutamate and sodium chloride were used together, both umami and salty taste were maintained.

Medium levels of transcription and replication related chromosomal instability are associated with poor clinical outcome

Genomic instability (GI) influences treatment efficacy and resistance, and an accurate measure of it is lacking. Current measures of GI are based on counts of specific structural variation (SV) and mutational signatures. Here, we present a holistic approach to measuring GI based on the quantification of the steady-state equilibrium between DNA damage and repair as assessed by the residual breakpoints (BP) remaining after repair, irrespective of SV type. We use the notion of Hscore, a BP “hotspotness” magnitude scale, to measure the propensity of genomic structural or functional DNA elements to break more than expected by chance. We then derived new measures of transcription- and replication-associated GI that we call iTRAC (transcription-associated chromosomal instability index) and iRACIN (replication-associated chromosomal instability index). We show that iTRAC and iRACIN are predictive of metastatic relapse in Leiomyosarcoma (LMS) and that they may be combined to form a new classifier called MAGIC (mixed transcription- and replication-associated genomic instability classifier). MAGIC outperforms the gold standards FNCLCC and CINSARC in stratifying metastatic risk in LMS. Furthermore, iTRAC stratifies chemotherapeutic response in LMS. We finally show that this approach is applicable to other cancers.

Liquefaction Vulnerability Analysis using N-SPT Value and Grain Size Analysis on Gumbasa Irrigation Canal in the Post-Disaster Petobo Area, Sulawesi

Strong earthquakes occurred in Central Sulawesi, Indonesia, in late 2018, causing an inheritance disaster, soil liquefaction on Gumbasa Irrigation Canal at Petobo, Sulawesi. Soil liquefaction is a phenomenon of a decreasing soil bearing capacity triggered by strong vibrations in certain soil conditions. It immediately changes the soil characteristic from solid to liquid. Liquefaction vulnerability analysis was done using Idriss-Boulanger’s simplified procedure based on SPT value in several spots. The Petobo liquefaction zone has seven boreholes, five of which are located near the Gumbasa Irrigation Canal. The soil sample at those boreholes was taken to the laboratory for further soil testing using grain size analysis. The simplified procedure is intended to calculate the safety factor using Cyclic Resistance Ratio, Cyclic Stress Ratio, and Magnitude Scaling Factor. The liquefaction vulnerability analysis resulted in the AB 1 – AB 3 area near Gumbasa Irrigation Canal, which liquefied. Meanwhile, LP 1 and LP 4 are contrary. LP 1 is located upstream of the canal, whereas LP 4 the downstream. Grain size analysis yields a consistent result that AB 1 – AB 3 soil is quite scattered inside the liquefiable constraint.

Local magnitude calibration of seismic events in the West Rand, Far West Rand, and Klerksdorp-Orkney-Stilfontein-Hartebeesfontein gold mining areas

Richter magnitudes for seismic events were calibrated for use as a Local magnitude scale in the West Rand (WR), Far West Rand (FWR), and Klerksdorp-Orkney-Stilfontein-Hartebeesfontein (KOSH) gold mining areas. Richter magnitudes are currently calculated from seismograms recorded by local surface cluster networks using tabulated calibration values for Southern California, published in 1958. The Richter (1958) model is incorrect for distances of less than 30 km and should be applied only to crustal earthquakes in regions with similar attenuation properties to those of Southern California. When compared to the South African National Seismograph Network (SANSN), the cluster networks, on average, overestimate seismic event magnitudes by approximately 0.1 of a magnitude unit. A calibrated Local magnitude scale was derived by means of a multiple regression analysis between the Local magnitudes reported by the SANSN and the largest zero-to-peak trace amplitudes measured on the cluster network horizontal seismograms, after modelling the attenuation of the seismic waves as these progress from the epicentre to the station position. Magnitudes reported by individual stations for the same event show a significant scatter around the average magnitude owing to the near-surface amplifications of the seismic waves at the recordings sites. Average magnitude should be estimated using as many magnitudes of individual stations as possible to ensure an accurate estimate. Larger event magnitudes should be compared with those recorded by the SANSN.

CPTu-based approaches for cyclic liquefaction assessment of alluvial soil profiles

Over the years, methods to assess cyclic liquefaction potential based on piezocone penetration tests (CPTu) have been developed. This paper presents a comparative study between three CPTu-based methodologies, mainly in terms of the normalization procedures of overburden stresses, equivalent clean sand resistance, and magnitude scaling factor (MSF). Four CPTu profiles from a pilot site in southwest Portugal are thoroughly analysed with different methods, in terms of factor of safety against liquefaction, the Liquefaction Potential Index (LPI), and the Liquefaction Severity Number (LSN). The site presents very heterogeneous soil profiles, composed of alluvial deposits. Due to the presence of significant sand-silt–clay interbedded layers, the influence of transition zones and the use of different soil behaviour type index (Ic) cut-off values were also considered. From these analyses, a set of recommendations is presented for CPTu-based liquefaction assessment. Based on the extensive database of CPTu results in the pilot site area, a new classification relating LPI and LSN is proposed to assess liquefaction severity and damage.

Liquefaction within a bedding fault: Understanding the initiation and movement of the Daguangbao landslide triggered by the 2008 Wenchuan Earthquake (Ms = 8.0)

The Daguangbao landslide was the most catastrophic mass movement triggered by the 2008 Wenchuan earthquake with a magnitude scale of Ms. 8.0. The landslide, which was 4.6 km long and 3.7 km wide, had a volume of approximately 1.2 × 109 m3. Since its occurrence, many assumptions regarding its initiation and movement mechanisms have been made; however, the mechanisms remain unclear. Our recent field evidence suggested that the Daguangbao landslide occurred along a saturated fault parallel to the bedding in the Paleozoic carbonate strata. We therefore examined whether the shear behavior of the fault material could have favored the initiation and movement of the Daguangbao landslide. First, we performed monotonic and cyclic loading tests on samples taken from the bedding fault breccia using ring-shear apparatus. We then conducted Newmark displacement analysis to examine the initiation and motion of the landslide. The laboratory results showed that the carbonate fault breccia on the sliding layer of the landslide has a high liquefaction potential and the friction coefficient at its steady-state under undrained condition could be as small as 0.04. We also found that with increase of shear displacement, the friction coefficients can at first exponentially increase to the peak-failure value and then exponentially decrease to the steady-state value. These relationships between the friction and shear displacements were incorporated in the Newmark analysis of landslide initiation and motion. The numerical calculation results showed that the landslide occurred 36 s after the 2008 Wenchuan earthquake origin time (at its hypocenter), and the landslide mass, with a speed of 94 m/s, collided with a riverbank in the 76th second. We infer that, in addition to the strong seismic force, pore-water pressure built up within the bedding fault during the seismic shaking, enhancing the instability of the Daguangbao slope, and a further increase of pore-water pressure with progress of sliding elevated the mobility of the landslide.

The precision and accuracy of measuring micro-scale erosion on shore platforms

Shore platforms evolve over millennial scales but understanding precisely how instantaneous processes scale over these longer periods is a major scientific quandary. A reason for this, is that erosion often occurs on the granular scale and measurement of magnitude and frequency of this decay is difficult. Over the past 50 years, a number of techniques have been used to quantify the micro-scale (0.01–10 mm) erosion of coastal bedrock, from direct surface contact techniques to those which involve remote sensing. The micro-erosion meter (MEM) and traversing micro-erosion meter (TMEM) are the most common techniques, recording erosion rates from <0.1 to 5 mm/yr on rock surfaces of c. 50 cm2. The traversing erosion beam (TEB) is specifically designed to measure rapid erosion (>10 mm/yr) while the Swantesson laser scanner (SLS) and close-range Structure-from-motion (SfM) photogrammetry have been used for observation of larger rock surfaces of 0.2 m2. The rock tablet method is used to investigate the individual processes operating on downwearing. By comparing their advantages and disadvantages, the T/MEM is suggested to continue to play an important role in monitoring surface lowering in conditions where the total erosion is 20 mm over the monitoring period, with close-range SfM recommended as ideal for quantifying erosion of 2–50 mm. However, all the instruments are biased in the field conditions under which they can be operated, and it is important for researchers to contextualise their measured surfaces in regards to a whole platform. Future studies will benefit from the combination of the ground-based methods with new techniques that provide finer morphological features at the regional scale or interpret the evolution of shore platforms over long timescales.

Altered Modulation of the Movement-Related Beta Desynchronization with Force in Stroke - a Pilot Study.

Conventional therapy improves motor recovery after stroke. However, 50% of stroke survivors still suffer from a significant level of long-term upper extremity impairment. Identifying a specific biomarker whose magnitude scales with the level of force could help in the development of more effective, novel, highly targeted rehabilitation therapies such as brain stimulation or neurofeedback. Four chronic stroke participants were enrolled in this pilot study to find such a neural marker using an Independent Component Analysis (ICA)-based source analysis approach, and investigate how it has been affected by the injury. Beta band desynchronization in the ipsilesional primary motor cortex was found to be most robustly scaling with force. This activity modulation with force was found to be significantly reduced, and to plateau at higher force than that of the contralesional (unaffected) side. A rehabilitation therapy that would target such a neuromarker could have the potential to strengthen the brain-to-muscle drive and improve motor learning and recovery.Clinical Relevance- This study identifies a neural marker that scales with motor output and shows how this modulation has been affected by stroke.

Resolving the Structural Debate for the Hydrated Excess Proton in Water.

It has long been proposed that the hydrated excess proton in water (aka the solvated "hydronium" cation) likely has two limiting forms, that of the Eigen cation (H9O4+) and that of the Zundel cation (H5O2+). There has been debate over which of these two is the more dominant species and/or whether intermediate (or "distorted") structures between these two limits are the more realistic representation. Spectroscopy experiments have recently provided further results regarding the excess proton. These experiments show that the hydrated proton has an anisotropy reorientation time scale on the order of 1-2 ps. This time scale has been suggested to possibly contradict the picture of the more rapid "special pair dance" phenomenon for the hydrated excess proton, which is a signature of a distorted Eigen cation. The special pair dance was predicted from prior computational studies in which the hydrated central core hydronium structure continually switches (O-H···O)* special pair hydrogen-bond partners with the closest three water molecules, yielding on average a distorted Eigen cation with three equivalent and dynamically exchanging distortions. Through state-of-art simulations it is shown here that anisotropy reorientation time scales of the same magnitude are obtained that also include structural reorientations associated with the special pair dance, leading to a reinterpretation of the experimental results. These results and additional analyses point to a distorted and dynamic Eigen cation as the most prevalent hydrated proton species in aqueous acid solutions of dilute to moderate concentration, as opposed to a stabilized or a distorted (but not "dancing") Zundel cation.

Assessing wind gust characteristics at wind turbine relevant height

Wind gust characteristics at wind turbine relevant height are closely tied with wind turbine design and wind power generation, however, they have not been detailed and documented. In this study, high-resolution wind data recorded by 3D sonic anemometers at a tall meteorological tower were analyzed to determine 12 descriptors of wind gusts and to identify the parent distributions that best fit these parameters. The main statistics were estimated using wind data from the 160 m height. It is found that the log-logistic distribution is most appropriate for a 10-min mean wind speed, gust magnitude, gust factor, and turbulence intensity; the gamma distribution appears to best fit peak factor, rise magnitude, lapse magnitude, lapse time, and gust length scale, while gust amplitude, rise time, and gust asymmetric factor are typically log-normally distributed. Gust factors tend to decrease with mean wind speed but increase as a function of turbulence intensity. The results also indicate that these wind gust descriptive parameters are height-dependent in which the 10-min mean wind speed, gust magnitude, gust length scale, rise time, and lapse time usually possess larger values at higher heights, whereas the remaining parameters exhibit negative correlation with height.

The Spatio-temporal Tectonic Condition and Microzonation Map of Malang Region after the 2021 M6.1 Malang Earthquake for Disaster Risk Mitigation

The M6.1 earthquake which hit Malang and its surroundings in 2021 resulted in fatalities and over 10,400 damaged houses. Several seismicity studies have been carried out for Malang region, but no specific studies have implied the M6.1 Malang earthquake yet. This study addresses such gap by investigating the Spatio-temporal b-value of Gutenberg-Richter Law and generating the microzonation maps of spectral acceleration by considering the effects of the M6.1 Malang earthquake. The earthquake data compiled from the national and international earthquake catalogs were homogenized into a moment magnitude scale. The b-value analysis was calculated using the Maximum Likelihood method and spatio-temporal mapping. Several ground motion prediction equations (GMPEs) were selected for subduction and shallow crustal earthquake sources to generate probabilistic seismic hazard analysis (PSHA). PSHA was conducted using the 2% probability of exceedance in 50 years. The results show that the b-value after the M6.1 Malang earthquake still tends to decrease, indicating a relatively-high stress level which accommodates the potential for large earthquakes in the future. The microzonation maps for Malang region show that the southern part of Malang has a higher spectral acceleration value than the others. Therefore, these findings can be considered in the future disaster mitigation plan.

Earthquake Magnitude Estimation using Precise Point Positioning

An accurate estimation of an earthquake magnitude plays an important role in targeting emergency services towards affected areas. Along with the traditional methods using seismometers, site displacements caused by an earthquake can be monitored by the Global Navigation Satellite Systems (GNSS). GNSS can be used either in real-time for early warning systems or in offline mode for precise monitoring of ground motion. The Precise Point Positioning (PPP) offers an optimal method for such purposes, because data from only one receiver are considered and thus not affected by other potentially not stable stations. Precise external products and empirical models have to be applied, and the initial convergence can be reduced or eliminated by the backward smoothing strategy or integer ambiguity resolution. The product for the magnitude estimation is a peak ground displacement (PGD). PGDs observed at many GNSS stations can be utilized for a robust estimate of an earthquake magnitude. We tested the accuracy of estimated magnitude scaling when using displacement waveforms collected from six selected earthquakes between the years 2016 and 2020 with magnitudes in a range of 7.5–8.2 Moment magnitude MW. We processed GNSS 1Hz and 5Hz data from 182 stations by the PPP method implemented in the G-Nut/Geb software. The precise satellites orbits and clocks corrections were provided by the Center for Orbit Determination in Europe (CODE). PGDs derived on individual GNSS sites formed the basis for ground motion parameters estimation. We processed the GNSS observations by the combination of the Kalman filter (FLT) and the backward smoother (SMT), which significantly enhanced the kinematic solution. The estimated magnitudes of all the included earthquakes were compared to the reference values released by the U. S. Geological Survey (USGS). The moment magnitude based on SMT was improved by 20% compared to the FLT-only solution. An average difference from the comparison was 0.07 MW and 0.09 MW for SMT and FLT solutions, respectively. The corresponding standard deviations were 0.18 MW and 0.22 MW for SMT and FLT solutions, which shows a good consistency of our and the reference estimates.

All-optical binary computation based on inverse design method

Abstract The development of information technology urgently requires ultrafast, ultra-low energy consumption and ultra-high-capacity data computing abilities. Traditional computing method of electronic chips is limited by the bottleneck of Moore’s Law. All-optical computing of photonic chips provides a promising way to realize such high-performance data computing abilities. Until now, it is still a huge challenge to realize all-optical four arithmetic operations at the same time on a photonic chip. Here, we propose a new encoding scheme for all-optical binary computation, including n-bit addition, subtraction, multiplication and division. We theoretically present n-bit calculation and experimentally demonstrate 1 bit calculation. The computation part includes a half binary adder and a shifter, whose feature sizes are only 2 μm × 19.5 μm and 4 μm × 9 μm, respectively. The half binary adder and shifter consist of three low-loss basic devices through inverse design method. The distance between two adjacent basic devices is smaller than 1.5 μm, within wavelength magnitude scale. The response time is the propagation time of the signal light in a single device, within 100 fs. The threshold energy consumption is within 10 fJ/bit. Our results provide a new method to realize ultrafast, ultra-low energy consumption and ultra-high-capacity data processing abilities all-optical n-bit binary computing.

Designing cascading disaster networks by means of natural language processing

In this study, we propose a method for evaluating cascading disasters using natural language processing to comprehensively and objectively extract causal relations between disaster events based on newspaper articles and construct cascading disaster networks. The applicability of this method is illustrated by employing data extracted from Japanese newspaper articles on the Great Hanshin-Awaji Earthquake and the Great East Japan Earthquake. Both disasters showed complex chain relations, and the proposed method extracted escalation points such as the “stoppage of factory production in the stricken area” for the Great Hanshin-Awaji Earthquake and “scheduled power outages outside the stricken areas” for the Great East Japan Earthquake based on each network structure. When matched with Alexander's magnitude scale for cascading disasters, both these catastrophic events were confirmed to reach Level 5.

Cascading disasters triggered by tsunami hazards: A perspective for critical infrastructure resilience and disaster risk reduction

Although many studies have investigated relationships between tsunami characteristics and the impact on physical property and infrastructure, such information cannot explain how the damage to each object or type of infrastructure can trigger failures of other facilities. To understand these connections and the cascading impacts, this article reviewed several recent damaging tsunami events in Japan and Indonesia, including the 2004 Indian Ocean tsunami and the 2011 Great East Japan Earthquake and tsunami. A proposed cascading magnitude scale was applied to each tsunami event to determine and categorize causes, effects, and escalation points. Large tsunamis tend to be associated with earthquakes, liquefaction, and landslides that multiply the scale of impact. The main escalation points for tsunami related disasters were found to be failures of tsunami warnings, power plants, medical facilities, educational facilities, and infrastructure. From the perspectives of critical infrastructure resilience and disaster risk reduction, analysis of cascading impacts of multiple recent tsunami events could contribute to greater understanding of economic, political, and social impacts that stem from technical decisions regarding infrastructure management. Detailed examples of tsunami cases demonstrate the potential scale and extent of damage from cascading events, and by identifying the roles and examples of escalation points, disaster managers and decision-makers can better mitigate cascading impacts by targeting and preventing escalation points. However, more detailed investigation on tsunami characteristics and their impact on failures of each type of facility is still needed to develop tools to support decision-making for better emergency management to address short- and long-term social impacts.

An Unknown Letter of Charles F. Richter about Magnitude Scales and His Relationship to Beno Gutenberg

Abstract I document here an unknown letter from Charles F. Richter to Arthur Gutenberg addressing the development of the magnitude scales and Richter’s relationship to Beno Gutenberg. Added to the letter are a description of its background, how it became known, and explanations about its historical contents.

Frequent spicy food consumption is associated with reduced capsaicin and salty taste sensitivity but unchanged sour taste or intranasal trigeminal sensitivity

The trigeminal and gustatory perceptions interact with each other during food consumption. Long-term repeated exposure to sensory stimuli leads to plasticity of sensory perception. The present study was conducted to test (i) the effect of frequent spicy food consumption on oral and intranasal trigeminal sensitivity, taste perception; and (ii) the effect of capsaicin at recognition threshold concentration on taste perception among individuals with different spicy food consumption frequencies. Seventy female college students were divided into the high frequency (HF; n = 35) and the low frequency (LF; n = 35) spicy consumption groups based on their self-reported spicy food consumption frequency. We assessed the recognition threshold (using a 3-alternative forced choice task) and suprathreshold intensity (on a generalized labeled magnitude scale) for capsaicin, salty and sour tastes, as well as the intranasal trigeminal sensitivity for menthol and mustard oil odors using the odor lateralization task. Sensitivity and intensity for salty and sour tastes were assessed with and without addition of capsaicin at the group-averaged recognition threshold level (1.38 μM). Compared with the LF group, the HF group had decreased sensitivity for capsaicin and salty taste, and decreased perceived irritative intensity of suprathreshold capsaicin. However, there was no difference for sour taste perception or intranasal trigeminal sensitivity between the two groups. The addition of 1.38 μM capsaicin showed no effect on salty or sour taste sensitivity. However, decreased supra-threshold intensity for salty taste was found in the presence of 1.38 μM capsaicin among participants with high frequency of spicy food consumption (the HF group). These findings suggested that long-term habitual spicy food consumption is related to alteration of oral perception of capsaicin and certain taste.

Flickering around the outburst cycle in Kepler dwarf novae

ABSTRACTTaking advantage of the unparalleled quantity and quality of high-cadence Kepler light curves of several dwarf novae, the strength of the flickering and the high-frequency spectral index of their power spectra are investigated as a function of magnitude around the outburst cycle of these systems. Previous work suggesting that the flickering strength (on a magnitude scale) is practically constant above a given brightness threshold and only rises at fainter magnitudes is confirmed for most of the investigated systems. As a new feature, a hysteresis in the flickering strength is seen in the sense that at the same magnitude level flickering is stronger during decline from outburst than during the rise. A similar hysteresis is also seen in the spectral index. In both cases, it can qualitatively be explained under plausible assumptions within the disc instability model model for dwarf nova outbursts.