Overview of the 2018 Cook Inlet Earthquake in Alaska ACEHR Meeting Boulder, CO April 30 – May 1, 2019 Jay Harris Acting NEHRP Deputy Director Engineering Laboratory National Institute of Standards and Technology U.S. Department of Commerce Earthquake Information Date: Friday, Nov. 30, 2018 at 8:29am Magnitude: Mw 7.0 (initial 6.6 to 7.2) Epicenter: 7 miles north of Anchorage Depth: 27 miles Fault Mechanism: Rupture occurred on an intraplate normal fault within the subducting Pacific Plate (beneath NA Plate) Aftershocks: > 600 aftershocks within 2 days of the earthquake Earthquake impacted Anchorage and Matanuska-Susitna Borough and Kenai Peninsula 2 Key Takeaways from this Event • Evaluation of available data (media coverage, first-hand observations, initial analysis of ground motion data) indicates that the surface intensity of the earthquake was not a “design-level” hazard event • This event provided another opportunity for the region to test in-place policies and procedures while providing a table exercise in the event of a higher intensity earthquake • No widespread significant structural damage observed; widespread nonstructural damage occurred • No one said that earthquake repairs have to be permanent to achieve functional recovery • The effects of and response to this event are not over 3 Hazard Response Spectra • Design-level Hazard – ASCE 7 (2016) 4 Developing Connections in AK • Sought to develop impactful connections with community stakeholders Municipality of Anchorage (Building Department) Division of Homeland Security and Source: M. Speicher (NIST) Emergency Management (AK, Anchorage, Mat-Su) Anchorage School District Alaska Department of Transportation, Central Region Regional Structural and Geotechnical Engineers (SEA-AK) Source: M. Speicher (NIST) Regional General Contractors (Alaska Demolition) Building Owners and Facility Managers 5 Impact to Commercial Structures • Non-structural component damage was widespread Ceiling assemblies and track systems, light fixtures Broken mechanical distribution lines due to insufficient seismic bracing HVAC equipment slid off supports and damaged connections (reports of fluid Source: Artic Today leaks) Water damage was significant (e.g., melting snow with gutter failures) Source: ABC 6 Impact to Commercial Structures • Some structural damage was observed Appears to be isolated to older construction (1980 era) No total collapsed commercial buildings, some have partial collapses of structural systems Buildings red-tagged unstable and Source: KTUU need repair Source: J. Harris (NIST) Source: J. Harris (NIST) Source: J. Harris (NIST) 7 Impact of Geotechnical Failures • Geotechnical failures slope stability failures and lateral spreading Liquefaction Settlement in non-compacted fill Source: ADN Source: J. Harris (NIST) Source: Alaska Star Source: ADN 8 Impact to Residential Structures • Primary Residential Damages (direct or indirect causes) Geotechnical failures No building code enforcement Construction-era practice Source: Alaska Star Source: ADN Source: ADN 9 Impact to Residential Structures • Earthquake insurance is underutilized in residential sector Voluntary insurance Can be cost prohibitive: 10%-30% deductible Some may not reimburse as high as replacement cost Source: J. Harris (NIST) Philosophy of homeowner Source: ADN Source: ADN Source: J. Harris (NIST) 10 Impact to School District • 92 Buildings, 86 Schools, 48K Students, 6K Employees 22 schools designated as community shelters Nonstructural damage was widespread among schools Some isolated structural damages 2 schools in Eagle River and 1 in Mat-Su were red-tagged Schools shut down after earthquake, re-opened Dec. 10th • One week after event (few extra days to help gain normalcy) Source: J. Harris (NIST) 11 Impact to School District • Representative nonstructural damage Source: KTVA Source: ADN Source: Twitter 12 Impact to School District • Eagle River Elementary & Gruening Middle Source: J. Harris (NIST) Source: J. Harris (NIST) Source: J. Harris (NIST) 13 Impact to Transportation Network • Observations 155 sites with some level of damage; primarily functional failures and not collapse Most damage associated with ground failure Vine Road Damage & Repair – Source: AK DOT (liquefaction, slope stability) Bridges were essentially undamaged Significant collapses were temporarily repaired within 4 days • Contracts done by “hand shakes” • Political changes had not occurred Source: ADN Source: Twitter Source: ADN 14 Impact to Lifeline Infrastructure • Lifeline Infrastructure performed well, companies worked around clock to remedy any failures Airport, Port of Anchorage, and rail system to Fairbanks shut down briefly, reopened after inspections to safely continue operations Public transportation in Anchorage was operational Source: ADN No reports of damage to power generation systems. Three power distribution companies reported widespread power outages, primarily due to tripped substations Several natural gas and water main breaches were reported, and the companies were steadily working to remedy breaches. Source: Twitter No reports of damage to telecommunication networks, and internet service providers were able to maintain services 15 Emergency Managers from Anchorage and Mat-Su • EOC responsible for situational awareness Community representatives report to EOC Some public reported cellular communications early issues, no issues with texting service “FirstNet” system, available bandwidth decreased Most felt they were “lucky” Preparedness and public awareness is an ever evolving effort Mass exodus of residents is a concern Source: M. Speicher (NIST) 16 Tsunami Warning for Anchorage • NOAA’s National Tsunami Warning Center warning issued 8:35am AKST for the “coastal areas of Cook Inlet and southern Kenai Peninsula” (south of Anchorage) Forwarded via sources (cell, tweets), with geography and timing of messages sometimes conflicting for recipients (Anchorage residents did receive) Some in Anchorage did evacuate, despite the fact that tsunami risk is extremely low in Anchorage, with no official tsunami evacuation routes or plans for the Anchorage area • 9:58am AKST cancellation of the tsunami warning after no tsunami activity was observed, but not sent out via cellular service (this is normal SOP) Need to customize distribution of cellular emergency messaging to appropriate sub-populations (work is in process) Opportunity to bring in NOAA to NEHRP activities; to help increase the knowledge-base across NEHRP on tsunamis 17 Discussions / Questions 18.