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