Loma Prieta

October 17, 1989 @ 5:04 PM.

That was the date of the last big earthquake that struck the bay area.

It was an Ml 6.9 temblor whose epicenter was in the Santa Cruz mountains along the San Andreas Fault System near the Loma Prieta Peak (after which the quake was named) but the effects of which were felt all over the bay area: In San Francisco alone, buildings and homes fell, freeways and roads were destroyed, and 66 people lost their lives on that day.

Loma Prieta was far from alone: There were two predictive foreshocks that occurred in June of 1988 and August of 1989 at Ml 5.3 and Ml 5.4, respectively. These two events were within roughly 5 km of the 1989 Loma Prieta shock and commonly thought to be foreshocks due to their proximity in space and time to the mainshock epicenter. Both quakes were rated a maximum intensity of VI (strong) and VII (very strong), respectively.

In the last seven days here in San Francisco we’ve been treated to no less than three shakers that I personally felt: An Ml 4.5 (1km SSE of Pleasant Hill, CA), Ml 4.7 (17km SSE of Tres Pinos, CA) , and Ml 3.5 (5km WSW of Colma, CA). According to seismologists, these shocks were not foreshocks but rather quakes along “well-known strike-slip faults in the San Francisco Bay Area”. While I trust the men and women of science on this subject, I still like to be prepared and so should you, Sprite, if you call the bay area home.

According to the USGS, ” The Bay Area has a 72% probability of producing a magnitude 6.7 or larger earthquake in the upcoming decades.” And the ‘big one’ could hit any time without warning although seismologists in the area are working an early warning system albeit not complete as of this writing.

So how do you survive a major or damaging earthquake? You Drop, Cover and Hold On.

When an earthquake happens, protect yourself right away:

  • If you are in a vehicle, pull over and stop. Set your parking brake.
  • If you are in bed, turn face down and cover your head and neck with a pillow.
  • If you are outdoors, stay outdoors away from buildings.
  • Do not get in a doorway.
  • Do not run outside.

Drop:

Drop wherever you are onto your hands and knees. If you’re using a wheelchair or walker with a seat, make sure your wheels are locked and remain seated until the shaking stops.

Cover:

Cover your head and neck with your arms. If a sturdy table or desk is nearby, crawl underneath it for shelter. If no shelter is nearby, crawl next to an interior wall (away from windows). Crawl only if you can reach better cover without going through an area with more debris. Stay on your knees or bent over to protect vital organs.

Hold On:

If you are under a table or desk, hold on with one hand and be ready to move with it if it moves. If you can’t find a table or desk, cover your head and neck with both arms and hands. If seated and unable to drop to the floor, bend forward, cover your head with your arms, and hold on to your neck with both hands.

As with any disaster, the best time to prepare for a damaging earthquake is before it happens (bullet points courtesy of ready.gov):

  • Practice Drop, Cover, and Hold On with family and coworkers.
  • Secure heavy items in your home like bookcases, refrigerators, televisions, and objects that hang on walls. Store heavy and breakable objects on low shelves.
  • Create a family emergency communications plan that has an out-of-state contact. Plan where to meet if you get separated.
  • Make a supply kit that includes enough food and water for at least three days, a flashlight, a fire extinguisher, and a whistle. Consider each person’s specific needs, including medication. Have extra batteries and charging devices for phones and other critical equipment. Do not forget the needs of pets and service animals.
  • Consider obtaining an earthquake insurance policy. A standard homeowner’s insurance policy does not cover earthquake damage.
  • Consider making improvements to your building to fix structural issues that could cause your building to collapse during an earthquake.

It’s also important to keep yourself safe after a damaging earthquake:

  • Expect aftershocks to follow the main shock of an earthquake.
  • Check yourself to see if you are hurt and help others if you have training. Learn how to be the help until help arrives.
  • If you are in a damaged building, go outside and quickly move away from the building. Do not enter damaged buildings.
  • If you are trapped, protect your mouth, nose, and eyes from dust. Send a text, bang on a pipe or wall, or use a whistle instead of shouting to help rescuers locate you.
  • If you are in an area that may experience tsunamis, go inland or to higher ground immediately after the shaking stops.
  • Text messages may be more reliable than phone calls. Save phone calls for emergencies.
  • Once you are safe, listen to local news reports for emergency information and instructions via battery-operated radio, TV, social media, or from cell phone text alerts. 
  • Be careful during the post-disaster cleanup of buildings and around debris. Do not attempt to remove heavy debris by yourself. Wear protective clothing, including a long-sleeved shirt, long pants, work gloves, and sturdy, thick-soled shoes during cleanup.
  • Register on the American Red Cross “Safe and Well” website so people will know you are okay.

For more information on preparing for and surviving the next damaging earthquake, visit the following site:

https://www.ready.gov/earthquakes

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