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Aggregates and seismic awareness

The more seismic-aware society [is], the better prepared people will be to minimise the effects of an earthquake.

Following my article last month on the damage from the 1906 San Francisco earthquake, it’s fitting to examine ways aggregate producers can be more seismic-aware. These are based on the ShakeOut Scenario, a wide-ranging exercise conducted to identify the physical, social and economic consequences of a magnitude 7.8 earthquake on the San Andreas Fault in southern California.

My conclusions for the ShakeOut were extrapolated from the observations of an experienced aggregate operator of the impacts caused by the magnitude 6.7 Northridge earthquake (1994).

Some aggregate, concrete and asphalt companies in earthquake-prone areas design and construct their facilities to withstand earthquakes and conduct regular inspections to ensure their facilities remain in sound operating condition. Facilities that take these precautions may suffer little or no damage during an earthquake. In contrast, poorly maintained operations could be severely damaged – some beyond repair.

{{image2-a:r-w:300}}Large earthquakes can cause significant damage to buildings and infrastructure. Emergency repairs and long-term reconstruction may require large amounts of aggregate, asphalt and concrete.

Being seismic-aware helps reduce the response time for emergency repairs. For example, after the 30 November, 2018, magnitude 7 earthquake in Anchorage, Alaska, all eight major transportation corridors that had been severely damaged were reopened within five days.

Bringing damaged facilities online after a quake depends heavily on spare parts and new equipment. For example, new crushers and screens may be in demand by both the aggregate and recycling industries.

Making concrete and asphalt requires materials from upstream cement plants. Damage to those facilities could limit the ability of local producers to meet demand. Similarly, power, water, gas and fuel outages will affect production.

Equally important, many of the skilled workers needed to operate aggregate and related facilities could be affected by the quake and tending to personal needs. For example, after Hurricane Katrina, aggregate operations in the Gulf Coast area took up to two weeks to assemble skilled personnel from the grieving workforce.

Producers can do many things to be ready for an earthquake (or other natural disasters, eg floods, storms, bushfires):

  • Individual facilities might benefit from a seismic safety audit by engineering professionals.
  • Spare parts can be positioned at plants themselves, or at central locations.
  • Standby sources of power-generating equipment, and portable processing facilities can be identified and advance lease or purchase agreements made.
  • Large producers with multiple plants can plan for intracompany transfer of product, personnel and equipment after a disaster.
  • Aggregate, asphalt and concrete producers can make intercompany mutual aid agreements, similar to those commonly used by police and firefighting agencies.

A plausible estimate of damage to the aggregate, concrete and asphalt industries following a disaster in your area, combined with prudent advanced preparations, should facilitate a timely response by the aggregate and related construction industries.

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