An official website of the United States government
Abstract Understanding the stress state before and after an earthquake is essential to study how stress on faults evolves during the seismic cycle. This study integrates wellbore failure analysis, laboratory experiments, and edge dislocation model to study the stress state before and after the Chi‐Chi earthquake. The post‐earthquake in‐situ stress state observed along boreholes of the Taiwan Chelungpu‐fault Drilling Project (TCDP) is heterogeneous due to lithological variations. Along the borehole, we observe that drilling‐induced tensile fractures are only present in sandstones, whereas breakouts are mostly present in silt‐rich rocks. Laboratory experiments on TCDP cores also show that tensile and compressive strength are weaker in sandstones than in silt‐rich rocks. These observations imply that both maximum and minimum horizontal principal stresses are higher in silt‐rich intervals. Extended leak‐off tests in the TCDP borehole also show lower minimum horizontal stress in sand‐rich intervals, consistent with the above observations. We combine these observations to estimate a profile of stress magnitudes along the well which explains the variability of stress states found in previous studies. The stress heterogeneity we observed underlines the importance of acknowledging the spatial scale that the stress data represent. We then use an edge dislocation model constrained by GPS surface displacements obtained during Chi‐Chi earthquake to calculate the coseismic stress changes. Our inferred pre‐earthquake stress magnitudes, obtained by subtracting the coseismic stress change from the post‐earthquake stress, suggest subcritical stress state before the earthquake despite the large displacements observed during the Chi‐Chi earthquake in the region where TCDP encountered the fault.
more »
« less
How disasters drive media channel preferences: Tracing news consumption before, during, and after Hurricane Harvey
Understanding public media channel preferences can inform preparedness plans, response strategies, and long-term recovery. However, questions remain about how media consumption changes across pre-crisis, crisis, and post-crisis phases. Past theories argue that media use may change for several reasons, including during times of societal conflict and challenge. These theories point to the belief that, during a crisis, we expect media channel use to change because media preferences during a crisis will be fundamentally different compared to everyday routines. This paper takes advantage of a survey fielded to Texas residents soon after Hurricane Harvey. Here we ask: (1) What media channels are most prominent in each crisis phase? and (2) Do media channel preferences change across crisis phases? We use simple descriptive statistics and chi-squares tests to describe media channel preferences across the three crisis phases by demographics. Additionally, we use alluvial diagrams to visualize media channel preferences over time. In total, 62% (n=174) of respondents reported no changes in channel preferences. However, chi-square tests identified significant differences in media use changes related to a handful of demographic characteristics. These findings are explored alongside theories that would hypothesize likely media use changes across pre-crisis, crisis, and post-crisis phases.
more »
« less
- Award ID(s):
- 1760484
- PAR ID:
- 10209665
- Date Published:
- Journal Name:
- Journal of Contingencies and Crisis Management
- ISSN:
- 0966-0879
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
In September 2019, Hurricane Dorian struck the Bahamas and the southeast United States, resulting in widespread damage and loss of life. Drawing from previous crisis communication research on both natural and man-made disasters, this study examines information seeking and medium preferences, attention allocation, and sex differences in these outcomes. Extant literature has found differences between men and women in terms of the volume and types of information wanted during a crisis event, as well as preferences for different media in times of crisis. This literature has yet to examine the degree to which attention allocation may be related to these outcomes. To address these issues in a naturalistic context, a large-scale survey was targeted at residents of states impacted by Hurricane Dorian. Results are consistent with previous research indicating that females engaged in more overall information seeking and sought more information seeking related to tangible goals. Females found interactive media (Internet and social media) to be more useful than males. Evidence was not detected concerning sex differences in the way people found out about the storm and sex differences in attention allocation detected. Results suggested small effects for perceived usefulness of television and Internet on attention allocation for both men and women. Implications for emergency management personnel and public officials are discussed.more » « less
-
A major goal in Engineering training in the U.S. is to continue to both grow and diversify the field. Project- and service-based forms of experiential, problem-based learning are often implemented with this as a goal, and Engineering Projects in Community Service (EPICS) High is one of the more well-regarded and widely implemented. Yet, the evidence based on if and how participation in such programs shapes student intentions and commitment to STEM pathways is currently limited, most especially for pre-college programming. This study asks: How do high school students’ engineering mindsets and their views of engineering/engineers change as they participate in project–service learning (as implemented through an EPICS High curriculum)? This study employed a mixed method design, combining pre- and post-test survey data that were collected from 259 matched students (63% minority, 43% women) enrolling in EPICS High (total of 536 completed pre-tests, 375 completed post-tests) alongside systematic ethnographic analysis of participant observation data conducted in the same 13 socioeconomically diverse schools over a two-year period. Statistical analyses showed that participants score highly on engineering-related concepts and attitudes at both pre- and post-test. These did not change significantly as a result of participation. However, we detected nuanced but potentially important changes in student perspectives and meaning, such as shifting perceptions of engineering and gaining key transversal skills. The value of participation to participants was connected to changes in the meaning of commitments to pursue engineering/STEM.more » « less
-
Abstract Establishment of microbial communities in neonatal calves is vital for their growth and overall health. While this process has received considerable attention for bacteria, our knowledge on temporal progression of anaerobic gut fungi (AGF) in calves is lacking. Here, we examined AGF communities in faecal samples from six dairy cattle collected at 24 different time points during the pre‐weaning (days 1–48), weaning (days 48–60), and post‐weaning (days 60–360) phases. Quantitative polymerase chain reaction indicated that AGF colonisation occurs within 24 h after birth, with loads slowly increasing during pre‐weaning and weaning, then drastically increasing post‐weaning. Culture‐independent amplicon surveys identified higher alpha diversity during pre‐weaning/weaning, compared to post‐weaning. AGF community structure underwent a drastic shift post‐weaning, from a community enriched in genera commonly encountered in hindgut fermenters to one enriched in genera commonly encountered in adult ruminants.Comparison of AGF community between calves day 1 post‐birth and their mothers suggest a major role for maternal transmission, with additional input from cohabitating subjects. This distinct pattern of AGF progression could best be understood in‐light of their narrower niche preferences, metabolic specialisation, and physiological optima compared to bacteria, hence eliciting a unique response to changes in feeding pattern and associated structural GIT development during maturation.more » « less
-
Introduction Widespread problems of psychological distress have been observed in many countries following the outbreak of COVID-19, including Australia. What is lacking from current scholarship is a national-scale assessment that tracks the shifts in mental health during the pandemic timeline and across geographic contexts. Methods Drawing on 244 406 geotagged tweets in Australia from 1 January 2020 to 31 May 2021, we employed machine learning and spatial mapping techniques to classify, measure and map changes in the Australian public’s mental health signals, and track their change across the different phases of the pandemic in eight Australian capital cities. Results Australians’ mental health signals, quantified by sentiment scores, have a shift from pessimistic (early pandemic) to optimistic (middle pandemic), reflected by a 174.1% (95% CI 154.8 to 194.5) increase in sentiment scores. However, the signals progressively recessed towards a more pessimistic outlook (later pandemic) with a decrease in sentiment scores by 48.8% (95% CI 34.7 to 64.9). Such changes in mental health signals vary across capital cities. Conclusion We set out a novel empirical framework using social media to systematically classify, measure, map and track the mental health of a nation. Our approach is designed in a manner that can readily be augmented into an ongoing monitoring capacity and extended to other nations. Tracking locales where people are displaying elevated levels of pessimistic mental health signals provide important information for the smart deployment of finite mental health services. This is especially critical in a time of crisis during which resources are stretched beyond normal bounds.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1111/1468-5973.12348
