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eNatech - Natural-Hazard Triggered Technological Accidents Database
Natech Accident
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Natech Near Miss
2019/07/04
2019 Ridgecrest earthquake sequence, United States, 2019
Site 117, United States
Published

Units Involved

  1. Infrastructure and specialised equipment
    Other: Other
    Several buildings in the naval base were constructed after the Loma Prieta earthquake in 1989. A large building stock in the naval base was nearly 30 years old and, potentially, not retrofitted according to the latest seismic design requirements as of 2019.

Event Sequences

  1. Severe damage
    1. Infrastructure and specialised equipment
    The U.S. Naval facilities and infrastructure near the earthquake epicentres sustained extensive damage.
    Initiating EventCritical EventMajor Event
    Natural Hazard: Other
    On the 4th of July 2019, the 2019 Ridgecrest earthquake sequence was triggered. This was a sequence of earthquake events that was marked by two major ground shakings and hundreds of aftershocks along two orthogonal seismic faults.
    The two major earthquakes occurred on:
    -04/07/2019 at 10:34 (local time) with a 6.4 Mw moment magnitude; and
    -05/07/2019 at 20:19 local time a 7.1 Mw moment magnitude.
    Both epicentres were located within the NAWS area.
    Building (Structural): Other
    In the aftermath of the 7.1 Mw event, the Naval base was declared as mission incapable and non-essential personnel were evacuated.

    The U.S. Naval facilities and infrastructure near the epicentres sustained extensive damage (according to a a radio interview that was based on an online presentation given by the Navy Facilities Engineering System Command (NAVFAC) on 01/08/2019).
    Contributing Factors
    Measure: Structural design / retrofitting for earthquakes: Unavailable
    Several buildings in the naval base were constructed after 1989, and, since then, there were several revisions in the U.S. building codes for the seismic design of structures. However, at the time of the 2019 Ridgecrest earthquakes, there was no requirement to seismically retrofit existing structures when building codes were modified, unless specifically requested by law.
    		--

Consequences

- At least 800 old buildings were damaged, including 69 buildings that each required a minimum amount of five million dollars for repair or replacement operations.
- A great number of large-size buildings was required to either be fully demolished or fully replaced. This included two hangars that were constructed in the 1940s, an air traffic control tower, laboratory facilities, and a fire bay.
- The road infrastructure near the epicentres was damaged.

The total replacement cost was estimated to be 5.2 billion USD, which included the actual economic losses due to damage and additional costs required for the seismic upgrade and retrofitting of existing facilities in the NAWS that did not comply with modern seismic codes.
Infrastructure (e.g. roads, railways, air transport)

Remedial Activities

Precautionary measures were taken to mitigate the risks posed by the damaged infrastructure.
Repair operations were also scheduled for the damaged road infrastructure near the epicentres.

Lessons Learned

Critical infrastructure should be seismically retrofitted when building codes are revised. Special consideration should be taken for the aged infrastructure.
ID: 121, Created: Kyriaki GKOKTSI, 2025-01-27 11:42:33 – Last Updated: Kyriaki GKOKTSI, 2025-01-27 11:58:36

Attachments

NoDescriptionFile Size
1.Radio interview - audio material4.69MB