Did You Feel It?

Did You Feel It?
Name	Did You Feel It?
Caption	Public seismic intensity reporting system
Founded	1990s
Founder	United States Geological Survey
Type	Scientific crowdsourcing platform
Location	United States
Key people	William Leith, Lori Dengler, David Wald

Did You Feel It? is a crowdsourced seismic intensity reporting system operated by the United States Geological Survey that collects public observations of felt ground shaking to map earthquake effects. The program converts thousands of individual responses into community intensity maps, complementing instrumental records from networks such as the Advanced National Seismic System and the Global Seismographic Network. It has informed emergency response and scientific analyses following events including the Northridge earthquake, Loma Prieta earthquake, and earthquakes in regions monitored by agencies like the California Geological Survey and the Japan Meteorological Agency.

Overview

Did You Feel It? aggregates subjective human reports through online questionnaires to estimate perceptual intensity distributions after earthquakes. Typical outputs include modified Mercalli intensity grids that are compared with instrumental magnitude and hypocenter data from providers such as the International Seismological Centre, the Global Centroid Moment Tensor Project, and the Incorporated Research Institutions for Seismology. The system interfaces with telemetry and alert services including the ShakeAlert system and regional observatories such as the Southern California Earthquake Center and the Pacific Tsunami Warning Center, enabling rapid situational awareness for entities like the Federal Emergency Management Agency and local emergency managers.

Methodology and Data Collection

Respondents complete standardized questionnaires modeled on intensity scales from historic compilations by researchers affiliated with institutions like the National Oceanic and Atmospheric Administration and the U.S. Geological Survey. Questions solicit location, building type, activity during shaking, and observed effects; responses are geolocated using user-provided city names cross-referenced with gazetteers such as the Geographic Names Information System and coordinate datasets from the National Aeronautics and Space Administration. Data processing pipelines employ statistical routines influenced by studies from the Seismological Society of America and academic groups at universities including Stanford University, University of California, Berkeley, and Massachusetts Institute of Technology to remove duplicates, weight reports, and interpolate intensities with methods comparable to those used in macroseismic studies by the European-Mediterranean Seismological Centre.

Instrumentation and Technology

Although fundamentally human-reported, Did You Feel It? is integrated with instrumental networks and modern web technologies. It ingests event metadata from seismic networks such as the Advanced National Seismic System and the Canadian Hazards Information Service, and correlates with waveform data processed by software like SeisComP and tools developed at the Incorporated Research Institutions for Seismology. The platform uses geospatial services from systems including the National Geospatial-Intelligence Agency datasets and mapping frameworks compatible with Google Maps APIs and GIS tools employed by the United States Forest Service and municipal planning agencies. Mobile web forms and outreach leverage platforms used by organizations like Twitter, Facebook, and university research groups to maximize respondent reach.

Applications and Impact

Community intensity maps produced by Did You Feel It? inform rapid damage assessments used by responders from agencies such as the Federal Emergency Management Agency, American Red Cross, and state-level emergency operations centers. Researchers from institutions like the Earthquake Engineering Research Institute and the Pacific Northwest Seismic Network use the data to refine ground motion prediction equations and vulnerability models applied in standards by the American Society of Civil Engineers and building codes overseen by organizations such as the International Code Council. International collaborations with entities like the European-Mediterranean Seismological Centre and the Japan Meteorological Agency have expanded macroseismic mapping practices, influencing post-event reconnaissance by teams from Helmholtz Centre Potsdam and academic partners at University of Tokyo.

Limitations and Criticisms

Critics note biases inherent to voluntary reporting: population density, internet access, language, and demographic factors skew sample distributions, echoing concerns raised in studies from Harvard University and University of Oxford. Urban centers with organizations like the Los Angeles County Fire Department may be overrepresented relative to rural communities monitored by agencies such as the Alaska Earthquake Center. Data quality issues arise when reports ambiguously describe effects, complicating classification against historic frameworks by researchers at the British Geological Survey and the Italian National Institute of Geophysics and Volcanology. Methodological critiques published in journals of the Seismological Society of America recommend integration with instrumental intensity proxies from dense arrays like those deployed by Instrumental Seismology Research Groups to reduce uncertainty.

History and Development

The program evolved from analog macroseismic surveys and postal questionnaires used in 19th and 20th-century investigations by figures associated with institutions like the Smithsonian Institution and the United States Coast and Geodetic Survey. With the rise of the internet in the 1990s, the United States Geological Survey launched online reporting forms, drawing on precedents set by macroseismic atlases from the International Association of Seismology and Physics of the Earth's Interior and case studies from events such as the 1994 Northridge earthquake. Subsequent enhancements incorporated automated ingestion of seismic event parameters from the Global Seismographic Network and collaborations with academic consortia including the Southern California Earthquake Center and the Incorporated Research Institutions for Seismology, while outreach efforts connected with media organizations like The New York Times and public science initiatives at institutions such as the Smithsonian Institution to boost public participation.

Category:Seismology