Challenges in seismic hazard assessment: Analyses of ground motion modelling and seismotectonic sources

Seismic hazard assessment has an important societal impact in describing levels of ground motions to be expected in a given region in the future. Challenges in seismic hazard assessment are closely associated with the fact that different regions, due to their differences in seismotectonics setting (and hence in earthquake occurrence) as well as socioeconomic conditions, require different and innovative approaches. One of the most important aspects in this regard is the seismicity level and the pre-existing knowledge about seismotectonics and fault behaviour in the region. The present thesis focuses on seismic hazard in three regions of very different tectonics in which different approaches for seismic hazard assessment were needed. In seismically active regions, standard probabilistic and deterministic approaches can be followed in assessing the hazard provided that the seismotectonic and geological information is available. In regions of low seismicity, this information is often incomplete and it may be necessary to start by studying in more detail the seismotectonic processes giving rise to the seismic hazard. The Marmara Sea and Sumatra regions are the main geographical areas where challenges in high seismicity areas are addressed. For addressing the seismic hazard assessment in low seismicity areas, the approach was to focus on the seismotectonic source characterization in various locations in Norway and adjacent areas. The Marmara Sea region is under a significant seismic hazard due to the short distance to the North Anatolian Fault which is believed to be close to rupture. This region is well studied in terms of tectonics and fault properties. However, the attenuation properties of the crust in the region have been uncertain. A new attenuation relation is established for the region, based on regressions performed on the background seismicity (paper 1). The obtained relation shows good agreement with previously used relations. Due to the increased level of knowledge about the active faults in the Marmara Sea, scenario based ground motion modelling provides a reliable estimate of the seismic hazard due to a future large earthquake. The predictive nature of such computations leads to uncertainties in the input parameters, the effect of which has not been well known previously. A study of the effect of varying input source and attenuation parameters (paper 2) shows that rise time, rupture velocity, stress drop and rupture initiation point are the most significant parameters in terms of ground motion level. The effect of parameters and the variability of ground motion are strongly frequency dependent. Another factor leading to uncertainties in simulated ground motion is that most simulations are performed at bedrock level without taking possible site amplifications into account. This latter problem is addressed in a separate study in the Ataköy area, SW Istanbul (paper 3), which shows that site amplification is significant over the whole area with amplification up to a factor of 2. The December 26, 2004 Sumatra-Andaman earthquake left many unanswered questions regarding the importance of ground shaking in the observed damage and, more generally, the nature of ground shaking caused by very large earthquakes. To address these issues, the event is modelled in terms of ground motion to see the effect of ground shaking in the regions near the fault rupture (paper 4). Results show that ground shaking was significant in northern Sumatra and the neighbouring islands and set bounds on the ground motion to be expected from such large events. The low seismicity in Norway and the surrounding areas makes it difficult to understand the relationship between the tectonics (active faults) and the earthquake activity. In order to improve this, three regions of significant seismic activity have been chosen for further seismotectonic investigations. The Jan Mayen region is, with its location on the mid-Atlantic ridge, the seismically most active region in Norway. Despite this fact, very little was previously known with respect to active fault structures. Locations of a M=6.0 earthquake and its aftershocks, combined with a detailed bathymetry, have provided new evidence about active tectonic structures in the region (paper 5). It is shown that major strike-slip earthquakes occur along the Koksneset fault, which seems to be the dominant structure in the Jan Mayen Fracture Zone. In addition, NE-SW oriented normal or oblique normal faults are being reactivated in the Jan Mayen Platform as a result of the deformation along the Koksneset fault. Deformation along the plate boundaries is significantly different from intraplate deformation. In this sense, the tectonic setting of Skagerrak situated in a basin within the Eurasian Plate is very different from Jan Mayen. This is reflected in the seismicity, which is much lower than for Jan Mayen but still high in comparison to other regions in Norway. Most earthquakes here have magnitudes less than 3, which in combination with the offshore location makes earthquake location challenging. Increased station coverage during the recent years has improved the location capabilities and the combination of relocated seismicity with reinterpreted seismic profiles and gravity and magnetic anomaly data has provided new clues about the origin of the Skagerrak seismicity (paper 6). A previously unknown graben structure, the Langust fault zone, is found at a location coinciding with the location of the local seismicity. This structure is believed to be the source of a large part of the Skagerrak earthquakes. In addition, activity seems to be present along the Sorgenfri-Tornquist Zone, as it is also the case further southeast in Kattegat. The Rana region in northern Norway is unique in the sense that several earthquake swarms have been registered here earlier. The installation of two temporary stations in this active region has provided high-quality recordings of events down to magnitude less than 0.5. In addition to providing new information about the seismotectonics in the region, these events have been used as ground truth in calibrating event detection based on waveform correlation (paper 7). In combination, the presented studies address some of the challenges associated with seismic hazard assessment, and can hopefully serve as a basis for further investigations in the future

Testing the Environmental Seismic Intensity Scale on Data Derived from the Earthquakes of 1626, 1759, 1819, and 1904 in Fennoscandia, Northern Europe

Earthquake environmental effects (EEEs) were compiled for the earthquakes of 1626, 1759, 1819, and 1904 in the Fennoscandian Peninsula, northern Europe. The principal source of information was the contemporary newspaper press. Macroseismic questionnaires collected in 1759 and 1904 were also consulted. We prepared maps showing newly discovered EEEs together with previously known EEEs and analyzed their spatial distribution. We assigned intensities based on the 2007 Environmental Seismic Intensity (ESI) scale to 27 selected localities and compared them to intensities assigned based on the 1998 European Macroseismic Scale. While the overall agreement between the scales is good, intensities may remain uncertain due to the sparsity of written documentation. The collected data sets are most probably incomplete but still show that EEEs are not unprecedented cases in the target region. The findings include landslides and rockfalls as well as cascade effects with a risk potential and widespread water movements up to long distances. The winter earthquake of 1759 cracked ice over a large area. This investigation demonstrates that the ESI scale also has practical importance for regions with infrequent EEEs

Bruk av SCOFF for diagnostisering av spiseforstyrrelser i allmennpraksis

Den initiale presentasjonen av spiseforstyrrelser i allmennpraksis er ofte kryptisk med diffuse fysiske og psykiske symptomer og derfor vanskelig å diagnostisere. Britiske studier har vist at under halvparten av klinisk presenterte spiseforstyrrelser identifiseres. Vi har liten grunn til å tro at det er vesentlig forskjellig i Norge. Det er en alminnelig oppfatning i litteraturen og blant spesialister på området at tidlig diagnostisering har en klar positiv effekt på pasientens prognose. Målet med oppgaven har vært å finne frem til et godt dokumentert tiltak som vil kunne bedre diagnostiseringen av spiseforstyrrelser i en norsk allmennpraksis. Etter en gjennomgang av temaet ved litteratursøk i Cochrane og Pubmed, samt samtaler med norske allmennleger og speisalister på fagfeltet, kom vi frem til at SCOFF bør brukes som et screeningverktøy ved mistanke om en spiseforstyrrelse. En SCOFF-anamnese er rask og enkel å gjennomføre og har høy negativ prediktiv verdi. Positiv SCOFF-anamnese må føre til videre utredning. KONKLUSJON: Vi ser SCOFF som et enkelt, godt tilgjengelig, billig og trygt verktøy for bruk i norsk allmennpraksis. Det egner seg godt til å utelukke en mistenkt spiseforstyrrelse, og kan gi et kraftig insitament for videre utredning

On-site and laboratory evaluations of soundscape quality in recreational urban spaces

Context: Regulations for quiet urban areas are typically based on sound level limits alone. However, the nonacoustic context may be crucial for subjective soundscape quality. Aims: This study aimed at comparing the role of sound level and nonacoustic context for subjective urban soundscape assessment in the presence of the full on-site context, the visual context only, and without context. Materials and Methods: Soundscape quality was evaluated for three recreational urban spaces by using four subjective attributes: loudness, acceptance, stressfulness, and comfort. The sound level was measured at each site and simultaneous sound recordings were obtained. Participants answered questionnaires either on site or during laboratory listening tests, in which the sound recordings were presented with or without each site’s visual context consisting of two pictures. They rated the four subjective attributes along with their preference toward eight sound sources. Results: The sound level was found to be a good predictor of all subjective parameters in the laboratory, but not on site. Although all attributes were significantly correlated in the laboratory setting, they did not necessarily covary on site. Moreover, the availability of the visual context in the listening experiment had no significant effect on the ratings. The participants were overall more positive toward natural sound sources on site. Conclusion: The full immersion in the on-site nonacoustic context may be important when evaluating overall soundscape quality in urban recreational areas. Laboratory evaluations may not fully reflect how subjective loudness, acceptance, stressfulness, and comfort are affected by sound level

A Reappraisal of the Luroy, Norway, Earthquake of 31 August 1819

Archives and libraries were visited to find previously unknown documents testifying to the Luroy, Norway, earthquake of 31 August 1819 in northernmost continental Europe. The focus here is on Sweden, Finland, and Russia, which are important for determining the area of perceptibility east of Norway. The new written sources include 12 notes or entries in original archived documents, six contemporary newspaper reports, and two recollections written down years later. The original documentation uncovered is contributory to establishing the authenticity of the observations in Finland and Sweden. The dates of the original documentation allow tracing of the dissemination of eyewitness accounts in writing from the inner area of perceptibility southward to the larger documentation and population centers. New sources of information include weather reports of the Royal Swedish Academy of Sciences, minutes of its meetings, and correspondence sent to the Senate in Finland. The minutes of meetings of the Academy indicate that ample data were collected in the Swedish province of Vasterbotten. We found no original Russian documentation but uncovered national newspapers that are more reliable than the previously used Parisian newspaper. To increase transparency, we provide the first list of macroseismic data points (MDPs) including the respective documentation that testify to the Luroy earthquake. A macroseismic intensity was assigned to a locality, using the European Macroseismic Scale of 1998, when adequate information was available. Accounting for the uncertainty of intensity assessment, the magnitude was estimated as moment magnitude M = 5.9 +/- 0.2, reconfirming the ranking as the largest onshore or nearshore earthquake in the historical seismicity record of Fennoscandia. In addition to the reappraisal of the 31 August 1819 earthquake, a macroseismic map is provided for the earthquake of 17 February 1819, which was felt in northern Finland and Sweden. Some of its MDPs were previously associated with the Luroy earthquake.Peer reviewe

Local site effects in Ataköy, Istanbul, Turkey, due to a future large earthquake in the Marmara Sea

Since the 1999 Izmit and Düzce earthquakes in northwest Turkey, many seismic hazard studies have focused on the city of Istanbul. An important issue in this respect is local site effects: strong amplifications are expected at a number of locations due to the local geological conditions. In this study we estimate the local site effects in the Ataköy area (southwestern Istanbul) by applying several techniques using synthetic data (hybrid 3-D modelling and 1-D modelling) and comparing to empirical data. We apply a hybrid 3-D finite-difference method that combines a complex source and wave propagation for a regional 1-D velocity model with site effects calculated for a local 3-D velocity structure. The local velocity model is built from geological, geotechnical and geomorphological data. The results indicate that strongest spectral amplifications (SA) in the Ataköy area occur around 1 Hz and that amplification levels are largest for alluvial sites where SA reaching a factor of 1.5-2 can be expected in the case of a large earthquake. We also compare our results to H/V (horizontal to vertical component of the recorded signal) spectral ratios calculated for microtremor data recorded at 30 sites as well as to ambient noise synthetics simulated using a 1-D approach. Because the applied methods complement each other, they provide comprehensive and reliable information about the local site effects in Ataköy. Added to that, our results have significant implications for the southwestern parts of Istanbul built on similar geological formations, for which, therefore, similar SA levels are expecte

Holding a foster child’s mind in mind: study protocol for a cluster-randomized controlled trial of mentalization-based therapy (MBT) for foster families

BACKGROUND: Children in foster care are psychologically vulnerable and show more social, developmental, and behavioral problems than those living with their family of origin. Many foster parents struggle to care for these children, some of whom have experienced severe adversity. Research and theory suggest that developing a strong and supportive foster parent-child relationship is essential for foster children to become more well-adjusted and experience a decrease in behavioral problems and emotional maladjustment. Mentalization-based therapy (MBT) for foster families aims at increasing the reflective functioning of the foster parents, thus promoting the development of more secure and less disorganized child attachment representations, which is subsequently proposed as a factor that reduces behavioral problems and emotional maladjustment in children and promotes their overall well-being. METHODS: This is a prospective cluster-randomized controlled trial with two conditions: (1) the intervention group participating in MBT, and (2) the control group who receive usual care. Participants are 175 foster families with at least one foster child aged 4-17 years with emotional or behavioral problems. The intervention will be offered to foster families by 46 foster care consultants from 10 municipalities in Denmark. The foster care consultants will be randomized to MBT training (n = 23) or usual care (n = 23). The primary outcome is the psychosocial adjustment of the foster child measured by the Child Behavior Checklist (CBCL) as reported by foster parents. Secondary outcomes include child well-being, parental stress, parent mental health, parent reflective function and mind-mindedness, parent/child relations, child attachment representations, and placement breakdown. In order to explore implementation fidelity as well as practitioner experiences, we will administer questionnaires designed for this study and conduct qualitative research exploring the practice of the MBT therapists. DISCUSSION: This trial is the first experimental study of a family therapeutic intervention based on attachment theory for foster families within the Scandinavian context. This project will contribute with novel knowledge on attachment representations in foster children and the effects of an attachment-based intervention on essential outcomes for foster families and children. Trial registration ClinicalTrials.gov NCT05196724. Registered on January 19, 2022

Citizen Seismology in the Arctic

Landslides, earthquakes and other natural disasters are expected to increase in the Arctic, yet our ability to make informed decisions about safety is tightly limited by lack of data. As part of the Integrated Arctic Observation System (INTAROS) project, geophones were installed by residents in Greenland and by University of Bergen in Svalbard in 2018. The purpose of the installations was to explore challenges and benefits of community-based data collection for seismological monitoring in the Arctic region. Raspberry Shake units with one/three-component velocity sensors were selected for the deployment, due to their user-friendly configuration, easy installation, and well established digital platform and web services. The purpose of engaging community members in the use of geophone sensors was to monitor earthquakes, cryoseisms (events generated by ice mass), and landslides. We report our findings with respect to challenges regarding the installation and operation of the Raspberry Shake sensors at both locations. Connecting community-based recordings with permanent seismological networks improved both the detection capability and the data support for understanding seismic events in Greenland. In contrast, finding suitable locations for deployments in Longyearbyen turned out to be challenging, because most buildings are constructed on poles due to the permafrost and indoor space is expensive. Promoting citizen seismology in the Arctic could improve monitoring of seismic events in the Arctic while simultaneously raising community awareness of natural hazards.publishedVersio

The role of leptin and other hormones related to bone metabolism and appetite regulation as determinants of gain in body fat and fat-free mass in 8-11-year-old children.

BACKGROUND: Regulation of body composition during childhood is complex. Numerous hormones are potentially involved. Leptin has been proposed to restrain weight gain, but results are inconsistent. OBJECTIVE: We examined whether baseline fasting levels of ghrelin, adiponectin, leptin, insulin, IGF-I, osteocalcin, and intact parathyroid hormone (iPTH) were associated with body composition cross sectionally and longitudinally in 633 8-11-year-olds. DESIGN: Data on hormones and body composition by dual-energy x-ray absorptiometry from the OPUS School Meal Study were used. We looked at baseline hormones as predictors of baseline fat mass index (FMI) or fat-free mass index (FFMI), and also subsequent changes (3 and 6 months) in FMI or FFMI using models with hormones individually or combined. RESULTS: Cross-sectionally, baseline leptin was positively associated with FMI in girls (0.211 kg/m(2) pr. μg/mL; 97.5% confidence interval [CI],0.186-0.236; P < .001) and boys (0.231 kg/m(2) pr. μg/mL; 97.5% CI, 0.200-0.261; P < .001). IGF-I in both sexes and iPTH in boys were positively associated with FMI. An inverse association between adiponectin and FFMI in boys and a positive association between IGF-I and FFMI were found in girls. In longitudinal models, baseline leptin was inversely associated with subsequent changes in FMI (-0.018 kg/m(2) pr. μg/mL; 97.5% CI, -0.034 - -0.002; P = .028) and FFMI (-0.014 kg/m(2) pr. μg/mL; 97.5% CI, -0.024 - -0.003; P = .006) in girls. CONCLUSIONS: Cross-sectional findings support that leptin is produced in proportion to body fat mass, but the longitudinal observations support that leptin inhibits gains in FMI and FFMI in girls, a finding that may reflect preserved leptin sensitivity in this predominantly normal weight population.Address all correspondence and requests for reprints to: Stine-Mathilde Dalskov, Department of Nutrition, Exercise and Sports, University of Copenhagen, Rolighedsvej 26, 1958 Frederiksberg C, Denmark. E-mail: [email protected]. This study was registered inClinicalTrials.gov as trial number NCT01457794. The OPUS study was financed by a Grant from the Nordea Foundation (grant number 02-2010-478 0389). A complete list of food suppliers providing full or partial food sponsorships to the study can be found at the website: http://foodoflife.ku.dk/ opus/wp/skolemadsprojektet/leverandorer. Sources of funding and donation had no role in the trial design; collection, analysis, interpretation of data or decision to publish.This is the accepted manuscript for a paper published in Journal of Clinical Endocrinology and Metabolism, March 2015, 100(3):1196 –1205, DOI: 10.1210/jc.2014-370