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Macroseismology plays a crucial role in earthquake hazard and risk analyses, tying earthquake occurrences and impacts from the past with those of the present and future. The use of macroseismic intensity has grown as the hazard layer within essential USGS and others’ real-time information products and even in presenting hazard maps in a form friendlier to nontechnical users. However, even with best practices, there are limitations to modern macroseismic data collection approaches. Whereas crowd-sourced intensities are robust for lower levels, they are poorly defined above intensity VII, where damage assessment requires knowledge of each building’s structural system. Likewise, the United States, New Zealand, and others employ the Modified Mercalli Intensity (MMI) scale, which is consistent with—yet inferior to—the more recently developed European Macroseismic Scale (EMS-98). We report on an IMS Working Group meeting held in October 2022 at the USGS Powell Center to address these and other issues and to work towards an IMS. Workshop goals were, first, to harmonize the MMI scale with EMS-98 for the US and NZ—which share several similar building types—by considering those structures and associated damage grades not well represented in the current EMS-98 building vulnerability table. Second, formalize the process of augmenting EMS-98 with vulnerability classes appropriate for building types in other countries, thus promoting a scale that can be employed globally. Such efforts require expanding the EMS-98 explanatory documents. Lastly, we discuss how standardized earthquake-damage data collection worldwide—as part of an IMS—could facilitate hazard and risk analyses., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

During the response to a moderate-to-large earthquake in New Zealand, there is a great need for information on the geographical distribution of the damage. Emergency responders and decision makers use this information to prioritise mitigation actions, such as evacuation procedures and building interventions. At present, GeoNet produces only maps with the strong-motion data (in Peak Ground Velocity, Peak Ground Acceleration or Modified Mercalli intensity [MMI]) from the last hour. In addition, for each earthquake, currently GeoNet produces only a map with the locations of highest MMI per mesh block. However, there are currently no available maps with a geographical distribution of the damage per earthquake. GeoNet is working on producing these shaking layer maps per event to be used by emergency responders and the public. The potential use of GeoNet���s ���Felt RAPID��� reports to produce shaking maps and complement strong-motion data is being analysed in this project. ���Felt RAPID��� is a database of crowdsourced data where the public chooses from a set of six cartoons depicting their experience of the earthquake. This is a large dataset that produces a great amount of data within minutes of the earthquake, with its current record being more than 52,000 reports submitted for one single event within a few minutes after the event. Using our experience with a recent method to group the more robust ���Felt Detailed��� reports from GeoNet, we will explore the possibility of using Felt RAPID data within the first 24���48 hours after a damaging earthquake. The felt reports have the potential to ���fill in the gaps��� far away from strong-motion stations, where otherwise results fully depend on attenuation models and thus increase their uncertainty. Results from this project show that intensities derived from Felt RAPID reports are consistent with those derived from Felt Detailed, as long as enough reports are being submitted for each community. A minimum of 10 felt reports, and ideally more, is needed to produce stable results. However, analysis using the same respondent filling in both Felt RAPID and Felt Detailed questionnaires indicates a tendency for Felt RAPID to overestimate low intensities (MMI2���4) and underestimate high intensities (MMI>=5) compared to Felt Detailed. This project has been developed in parallel to GeoNet���s ���Shaking Layers��� project, which has started this year, with the aim of developing automatised shaking layer maps within minutes of a moderate-to-large earthquake in New Zealand. Data from the stakeholder engagements carried out during this project will be used in GeoNet���s ���Shaking Layers��� project to develop a product that fulfils the end users��� needs. Until now, the Felt RAPID database has been used only for public communication purposes. Its use in emergency response has not been analysed in detail. The project is largely focused on stakeholder engagements to understand the end-user needs for hazard information following a damaging earthquake. We carried out empathy interviews with key stakeholders, as well as two half-day workshops (one in person and one online) with a wider community of end users. During these engagements, we gathered key information on end-users��� needs for hazard information following a damaging earthquake in New Zealand. The workshops caused great interest and positive feedback and showed the willingness for participants to keep informed and participate in the two projects. Results from these stakeholder engagements are provided in this report. The ���Shaking Layers��� project from GeoNet will continue engaging with stakeholders (auth)

The habitability and functionality of buildings following earthquake events has a significant impact on the recovery process. Understanding the factors that influence levels of post-event habitability and functionality can assist in identifying areas for improvement in risk reduction and resilience and allows for improved modelling of social impacts. We developed an online survey to gather data from individuals that had experienced recent earthquake events in New Zealand. Broadly, questions were asked regarding the following categories: the earthquake event and personal experience, characteristics of the building that is being reported on, description of the building damage and utility outage, the relocation decisions made, and demographic information. We ran the survey from November 2018 to May 2019, and we received 147 completed responses. The majority of survey responses were regarding the impacts of the 2016 Kaikōura earthquake and the 2010–2011 Canterbury earthquake sequence, and most responses (over 80%) were regarding residential buildings. The frequency of responses was weighted towards lower levels of building damage. Relating building damage to utility outage time enabled the development of a cumulative density function for predicting electricity outage time, which can be used for impact modelling. The function is an example of what can be created using the type of data collected in the survey. The main reasons respondents moved out of buildings were building damage, disruption to utilities and fear of being in the building. This finding is in line with experiences from overseas events reported in the literature. Displaced residents tend to prefer to stay close to their original location and are out of their buildings for a wide variety of timeframes (close to a third do not return). The most common reasons respondents cited for returning to their building were restoring normal routine, restoration of utilities, being allowed to return, and feeling safe enough to return. The main limitations of the survey and results are due to the relatively small sample sizes for many questions, and the inability to account for all demographics, meaning the population may not be fully represented. The insights provided by the results of this survey are useful as a beginning step towards quantification of the social impacts of earthquakes in the built environment. Targeted data collection and efforts towards obtaining larger sample sizes have the potential to produce very useful datasets. Once developed into predictive functions, modelling of earthquake impacts could be significantly improved. (auth)