Accommodating ~9 m of dextral slip on the Kekerengu Fault through ground deformation during the Mw 7.8 Kaikōura Earthquake, November 2016

<p>The Mw 7.8 Kaikōura earthquake of November 14th 2016 provided unprecedented opportunities to understand how the ground deforms during large magnitude strike-slip earthquakes. The re-excavation and extension of both halves of a displaced paleoseismic trench following this earthquake provided an opportunity to test, refine, and extend back in time the known late Holocene chronology of surface rupturing earthquakes on the Kekerengu Fault. As part of this thesis, 28 organic-bearing samples were collected from a suite of new paleoseismic trenches. Six of these samples were added to the preferred age model from Little et al. (2018); this updated age model is now based on 16 total samples. Including the 2016 earthquake, six surface rupturing earthquakes since ~2000 cal. B.P. are now identified and dated on the Kekerengu Fault. Based on the latest five events (E0 to E4), this analysis yields an updated mean recurrence interval estimate for the Kekerengu Fault of 375 ± 32 yrs (1σ) since ~1650 cal. B.P. The older, sixth event (E5) is not included in the preferred model, as it may not have directly preceded E4; however, if this additional event is incorporated into an alternative age model that embraces all six identified events, the mean recurrence interval estimate (considered a maximum) calculated is 433 ± 22 yrs (1σ) since ~2000 cal. B.P. Comparison of structures on an identical trench wall logged both before and after the 2016 earthquake, and analysis of pre- and post-earthquake high resolution imagery and Digital Surface Models (DSMs), has allowed the quantification of where and how ~9 m of dextral-oblique slip was accommodated at this site during the earthquake. In addition to this, I analyse the coseismic structure of the adjoining segment of the 2016 ground rupture using detailed post-earthquake aerial orthophotography, to further investigate how geological surface structures (bulged-up moletrack structures) accommodated slip in the rupture zone. These combined analyses allowed me to identify two primary deformation mechanisms that accommodated the large coseismic slip of this earthquake, and the incremental effect of that slip on the structural geology of the rupture zone. These processes include: a) discrete slip along strike-slip faults that bound a narrow, highly deformed inner rupture zone; and b), distributed deformation within this inner rupture zone. The latter includes coseismic clockwise rotation of cohesive rafts of turf, soil and near-surface clay-rich sediment. During this process, these “turf rafts” detach from the underlying soil at a mean depth of ~0.7 m, shorten by ~2.5 m (in addition to shortening introduced by any local contractional heave), bulge upwards by < 1 m, and rotate clockwise by ~19° - while also separating from one another along fissures bounded by former (now rotated) synthetic Riedel faults. This rotational deformation accommodated ~3 m of dextral strike-slip (of a total of ~9 m), after which this rotation apparently ceased, regardless of the total slip or the local kinematics (degree of transpression) at any site. The remaining slip was transferred onto later forming, throughgoing faults as discrete displacement. Analysis of the morphology and amplitude of these moletracks suggests that an increase in the degree of transpression (value of contractional heave) at a site increases the magnitude of shortening and the finite longitudinal strain absorbed by the rotated turf rafts, but does not necessarily contribute to an increase in height (generally 0.33-0.53 m on all parts of the fault). Rather, the comparison of these moletracks with those described by other authors suggests that a more controlling factor on their height is the clay content and cohesion of material deformed into the moletracks. Finally, comparison of the before and after cross-sections of the displaced paleoseismic trench has provided, for the first time, insight into how large magnitude strike-slip ruptures are expressed in the fault-orthogonal view typical of paleoseismic trenches. Although this rupture involved ~9 m of dextral strike-slip, the cross-sectional view of the re-excavated trenches was dominated by the much lesser component of fault-perpendicular contractional heave (~1.3 m) that occurred in 2016, which did not occur in previous paleoearthquakes at the same site (these were, by contrast, transtensional). This heave was expressed as up to ~2 m of fault-transverse shortening in the inner rupture zone of the trenches, while the ~9 m of strike-slip only created cm-scale offsets across faults. Previous earthquakes at the site were expressed as cm-dm scale, mostly normal dip-separations of sub-horizontal stratigraphic units across faults, suggesting that a change in local kinematics (of ~8°) must have occurred in 2016. Such a small kinematic change may drastically impact the overall ground expression of strike-slip earthquakes - producing also complicated structures including overprinting fault strands in the rupture zone (to a few metres depth). This information poses challenges for structural geologists and paleoseismologists when interpreting (the significance of) structures in future trench walls.</p>

Accommodating ~9 m of dextral slip on the Kekerengu Fault through ground deformation during the Mw 7.8 Kaikōura Earthquake, November 2016

<p>The Mw 7.8 Kaikōura earthquake of November 14th 2016 provided unprecedented opportunities to understand how the ground deforms during large magnitude strike-slip earthquakes. The re-excavation and extension of both halves of a displaced paleoseismic trench following this earthquake provided an opportunity to test, refine, and extend back in time the known late Holocene chronology of surface rupturing earthquakes on the Kekerengu Fault. As part of this thesis, 28 organic-bearing samples were collected from a suite of new paleoseismic trenches. Six of these samples were added to the preferred age model from Little et al. (2018); this updated age model is now based on 16 total samples. Including the 2016 earthquake, six surface rupturing earthquakes since ~2000 cal. B.P. are now identified and dated on the Kekerengu Fault. Based on the latest five events (E0 to E4), this analysis yields an updated mean recurrence interval estimate for the Kekerengu Fault of 375 ± 32 yrs (1σ) since ~1650 cal. B.P. The older, sixth event (E5) is not included in the preferred model, as it may not have directly preceded E4; however, if this additional event is incorporated into an alternative age model that embraces all six identified events, the mean recurrence interval estimate (considered a maximum) calculated is 433 ± 22 yrs (1σ) since ~2000 cal. B.P. Comparison of structures on an identical trench wall logged both before and after the 2016 earthquake, and analysis of pre- and post-earthquake high resolution imagery and Digital Surface Models (DSMs), has allowed the quantification of where and how ~9 m of dextral-oblique slip was accommodated at this site during the earthquake. In addition to this, I analyse the coseismic structure of the adjoining segment of the 2016 ground rupture using detailed post-earthquake aerial orthophotography, to further investigate how geological surface structures (bulged-up moletrack structures) accommodated slip in the rupture zone. These combined analyses allowed me to identify two primary deformation mechanisms that accommodated the large coseismic slip of this earthquake, and the incremental effect of that slip on the structural geology of the rupture zone. These processes include: a) discrete slip along strike-slip faults that bound a narrow, highly deformed inner rupture zone; and b), distributed deformation within this inner rupture zone. The latter includes coseismic clockwise rotation of cohesive rafts of turf, soil and near-surface clay-rich sediment. During this process, these “turf rafts” detach from the underlying soil at a mean depth of ~0.7 m, shorten by ~2.5 m (in addition to shortening introduced by any local contractional heave), bulge upwards by < 1 m, and rotate clockwise by ~19° - while also separating from one another along fissures bounded by former (now rotated) synthetic Riedel faults. This rotational deformation accommodated ~3 m of dextral strike-slip (of a total of ~9 m), after which this rotation apparently ceased, regardless of the total slip or the local kinematics (degree of transpression) at any site. The remaining slip was transferred onto later forming, throughgoing faults as discrete displacement. Analysis of the morphology and amplitude of these moletracks suggests that an increase in the degree of transpression (value of contractional heave) at a site increases the magnitude of shortening and the finite longitudinal strain absorbed by the rotated turf rafts, but does not necessarily contribute to an increase in height (generally 0.33-0.53 m on all parts of the fault). Rather, the comparison of these moletracks with those described by other authors suggests that a more controlling factor on their height is the clay content and cohesion of material deformed into the moletracks. Finally, comparison of the before and after cross-sections of the displaced paleoseismic trench has provided, for the first time, insight into how large magnitude strike-slip ruptures are expressed in the fault-orthogonal view typical of paleoseismic trenches. Although this rupture involved ~9 m of dextral strike-slip, the cross-sectional view of the re-excavated trenches was dominated by the much lesser component of fault-perpendicular contractional heave (~1.3 m) that occurred in 2016, which did not occur in previous paleoearthquakes at the same site (these were, by contrast, transtensional). This heave was expressed as up to ~2 m of fault-transverse shortening in the inner rupture zone of the trenches, while the ~9 m of strike-slip only created cm-scale offsets across faults. Previous earthquakes at the site were expressed as cm-dm scale, mostly normal dip-separations of sub-horizontal stratigraphic units across faults, suggesting that a change in local kinematics (of ~8°) must have occurred in 2016. Such a small kinematic change may drastically impact the overall ground expression of strike-slip earthquakes - producing also complicated structures including overprinting fault strands in the rupture zone (to a few metres depth). This information poses challenges for structural geologists and paleoseismologists when interpreting (the significance of) structures in future trench walls.</p>

Evaluation model of LID facilities based on the influence of water resource value

Low-impact development (LID) facilities can not only effectively control rainwater runoff and its pollution, but also enhance the value of urban water resources in water systems. Current studies usually pay more attention to the effect of pollution control indicators, and there are few reports on the evaluation of LID facilities from the perspective of enhancing the value of water resources. Taking the Maluan Bay area of Haicang, Xiamen as an example, an evaluation model of water resource value was established based on the SWMM software and the pollution loss model. From the perspective of economic quantification, the value of water resources brought by three types of LID facilities, such as green roofs, permeable pavement and infiltration gallery, under rainfall conditions in different recurrence intervals was simulated and calculated. In the single rainfall event of 1–10a recurrence interval, the water resource value brought by the green roofs is 679.14–787.49 RMB/hm2, the permeable pavement is 79.07–383.37 RMB/hm2 and the infiltration gallery is 825.45–1,021.79 RMB/hm2. The results show that the value of water resources brought by the three types of LID facilities decreases with the increase of rainfall recurrence interval.

Paleotsunamis on the Southern Hikurangi Subduction Zone, New Zealand, Show Regular Recurrence of Large Subduction Earthquakes

Geological records of subduction earthquakes, essential for seismic and tsunami hazard assessment, are difficult to obtain at transitional plate boundaries, because upper-plate fault earthquake deformation can mask the subduction zone signal. Here, we examine unusual shell layers within a paleolagoon at Lake Grassmere, at the transition zone between the Hikurangi subduction zone and the Marlborough fault system. Based on biostratigraphic and sedimentological analyses, we interpret the shell layers as tsunami deposits. These are dated at 2145–1837 and 1505–1283 yr B.P., and the most likely source of these tsunamis was ruptures of the southern Hikurangi subduction interface. Identification of these two large earthquakes brings the total record of southern Hikurangi subduction earthquakes to four in the past 2000 yr. For the first time, it is possible to obtain a geologically constrained recurrence interval for the southern Hikurangi subduction zone. We calculate a recurrence interval of 500 yr (335–655 yr, 95% confidence interval) and a coefficient of variation of 0.27 (0.0–0.47, 95% confidence interval). The probability of a large subduction earthquake on the southern Hikurangi subduction zone is 26% within the next 50 yr. We find no consistent temporal relationship between subduction earthquakes and large earthquakes on upper-plate faults.

INTEGRATING DIGITAL ELEVATION MODEL, LANDUSE/LANDCOVER AND FLOOD FREQUENCY ANALYSIS: A DETERMINISTIC APPROACH TO FLOOD INUNDATION AND RISK MODELING OF MAKURDI ALONG ITS RIVER BENUE REACH

The study applied GIS techniques to integrate Digital Elevation Model (DEM), Landuse/Landcover (LULC) and flood frequency analyses to determine extent of flood hazard inundation of Makurdi town along its River Benue reach following extreme discharges and stage levels. Annual maximum stage and discharge data from 1914 to 2015 was analyzed using Gumbel’s distribution to predict flood flow for different return periods (T): 5, 10, 25, 50, 75, and 100. A goodness of fit test was conducted using Chi square statistics, which was insignificant indicating that River Benue at Makurdi flood flow fits the Gumbel distribution. Combining this result with DEM and classified LULC data, the GIS spatial analyst tool was used to estimate the areal extent of landuse that will be inundated per return period. The result shows extent of flood inundation based on current landuse pattern for the respective return periods of predicted extreme stage / discharge likely due to climate change to be as follows: bareland (1.69, 1.74, 1.78, 1.84, 1.83, 1.89 km2); settlement/built-up (5.38, 5.50, 5.63, 5.76, 5.76, 6.02 km2); farmlands (272.27, 283.59, 295.10, 306.43, 306.43,and 317.49 km2); Vegetation (91.56, 95.26, 98.78, 102.45, 102.48, and 105.95 km2); water bodies (0.21,0.21, 0.22,0.22,0.22, and 0.22 km2) and Wetlands (44.14, 45.80, 47.48, 30.36,49.42 and 50.78 km2). This reveals a general increase in the extent of flood inundation at progressive recurrence interval, and predicted rising extreme river stage heights / discharge except for the flood with 50 year recurrence interval. The study recommends that NEMA and Benue State Urban Development Board

Sensitivity Assessment of Wilms tumor gene (WT1) expression in Glioblastoma Using qPCR and Immunohistochemistry and its association with IDH1 mutation, and recurrence interval

The authors have requested that this preprint be withdrawn due to erroneous posting.

Analysis of Drought Characteristics in Northern Shaanxi Based on Copula Function

Precipitation is low and drought occurs frequently in Northern Shaanxi. To study the characteristics and occurrence and development of drought events in Northern Shaanxi is beneficial to the prevention and control of drought disasters. Based on the monthly rainfall data of 10 meteorological stations in Northern Shaanxi from 1960 to 2019, the characteristic variables of drought events at each meteorological station in Northern Shaanxi were extracted by using run theory and copula function. The joint probability distribution and recurrence period were obtained by combining the duration and intensity of drought, and the relationship between drought characteristics and crop drought affected area was studied. The results show that (1) from 1960 to 2019, drought events mainly occurred in Northern Shaanxi with long duration and low severity, short duration and high severity, or short duration and low severity, among which the frequency of drought events that occurred in Yuyang and Baota districts was higher. The frequency of light drought and extreme drought was more in the south and less in the north, while the frequency of moderate drought and severe drought was more in the north and less in the south. (2) The optimal edge distribution of drought intensity and drought duration in Northern Shaanxi is generalized Pareto distribution, and the optimal fitting function is Frank copula function. The greater the duration and intensity of drought, the greater the cumulative probability and return period. (3) The actual recurrence interval and the theoretical recurrence interval of drought events in Northern Shaanxi were close, and the error was only 0.1–0.3a. The results of the joint return period can accurately reflect the actual situation, and this study can provide effective guidance for the prevention and management of agricultural dryland in Northern Shaanxi.