Think, drop, cover and hold on

An earthquake measured at a magnitude of about 6.5 or greater has the potential to create a fault rupture, causing a displacement in the surface of the earth that could be anywhere from several inches to 60 feet in height, depending on the magnitude of the quake. Photo courtesy Charles Watson
Samantha P. Hawthorne

  Starting as early as Feb. 7 in the central United States, families, businesses, schools and organizations all over the world are preparing to “drop, cover and hold on” in an effort to be ready when an earthquake strikes.

  Originating in Southern California only five years ago, The Great ShakeOut has since spread throughout the U.S. and has even earned the attention of other countries such as Japan and Italy.

  According to its website, The Great ShakeOut is a way for people to practice how to protect themselves during a major earthquake. It is organized annually to encourage “you, your community, your school, or your organization to review and update emergency preparedness plans and supplies, and to secure your space in order to prevent damage and injuries.”

  While most states and countries outside of the U.S. will be observing ShakeOut drills Oct. 17, other territories such as the central U.S. and Utah have scheduled different dates.

  Even though the nationwide drill is still months away, more than 950,000 Californians are already registered for The Great California ShakeOut. Last year, out of the 18 million participants worldwide, 9.4 million California residents made the pledge to “drop, cover and hold on.”

  “This drill, which can be conducted in as little as 90 seconds, provides a timely and relevant opportunity for the entire community to get prepared, practice what to do to be safe, and learn what emergency plans need to be improved,” wrote Secretary of Homeland Security Janet Napolitano and Secretary of Education Arne Duncan.

  Though it is not often thought of as a high-risk territory, Charles Watson, president and chief geologist for Advanced Geologic Exploration Inc. in Chester, said that Plumas County is considered a very active tectonic area. In addition to this, the state of California has a higher risk of earthquakes compared to the rest of the country.

  For this reason, it is important that earthquake safety is not overlooked. Those interested in a fun way to give attention to earthquake preparedness can register for the ShakeOut at The website provides a plethora of free information on how to manage an event and engage community involvement.

Earthquake history

  Since the surface of the Earth is in constant motion, the rocks within it can rub against each other, sink beneath each other or spread apart from each other.

Although it has not erupted since 1917, Lassen Peak is considered one of the most likely volcanoes in the North American mountainous region to erupt during the coming decades and centuries. According to Charles Watson, president and chief geologist of Advanced Geologic Exploration Inc., “All major volcanic eruptions are preceded by earthquakes. There is no way an eruption can happen without there being earthquakes.” Photo courtesy National Park Service

  Eventually, the rocks cannot withstand any more strain and they break in half, causing a displacement of rock on the surface of the earth and, ultimately, causing the surrounding area to shake.

  “The release of energy that comes from the rock breaking is what causes the shaking of the ground that we feel. The larger displacement, the bigger the earthquake,” said Watson.

  Sometimes the displacement will cause a break in the surface of the earth, creating a “fault” or “rupture plain.” For this to happen, however, the magnitude of the earthquake would have to reach at least 5.5 on the Richter scale.

  Depending on the magnitude, a visible displacement could be as small as a few inches to as large as 60 feet or more. “A magnitude measured at 6.0 could create a fault of about 12 inches, whereas magnitude of 9.0 has the potential to create a 45- to 60-foot fault,” said Watson.

  “The likelihood of a magnitude 10.0 is very remote but is possible. Those types of very large earthquakes are probably more related to meteor impacts or global catastrophes.” He said the largest earthquake ever recorded, in Chile in 1960, had a magnitude of 9.6.

  Earthquakes do not always form on the surface, however. The deepest earthquakes can occur up to 560 miles beneath the earth’s surface. “After that depth, the rocks become too warm to break and instead bend like plastic. At that level, you don’t get the same energy release, so you don’t feel the earth shake,” said Watson.

  The frequency of earthquake activity varies considerably over decades. “Geologists can look back in time thousands, if not hundreds of thousands of years and measure where the ground has ruptured on the surface,” said Watson.

  This helps determine how tectonically active a specific area is. “Over time and decades, fault locations are recorded on a map, which shows the areas where earthquakes happen more frequently than others.”

Local earthquake activity

  Since 1971, the average earthquake activity in Northeastern California is between 10 and 20 earthquakes per week.

  “When it falls below 10 in a week it is considered below-average; 20 to 30 is above-average.

  “There was only one week in the last decade when the Richter scale did not record any earthquakes registering a magnitude 1.0 or stronger. This is truly amazing,” said Watson.

  When a large earthquake does occur, it is always followed by an aftershock sequence, which causes a change in the frequency of activity.

  “Mount Lassen has been going through mild to active stages since recordings began. In 2002, there was a significant increase in activity, which correlated to elevated hot springs temperatures.

  “The geological community was concerned a large earthquake or volcanic eruption was about to happen. It was a very nervous time,” said Watson. The activity eventually slowed down and conditions went back to normal.

  He explained that a sequence of earthquakes is usually a sign of foreshocks, and indicate a larger earthquake or volcanic eruption could be on the way.

  Although the typical earthquake in the northeast is only measured at a magnitude of 1.0 to 2.0, larger earthquakes are possible. The largest in this area have been measured at 7.4 to 7.8, according to Watson.

  “There is a good likelihood that a major earthquake could happen in your child’s lifetime,” he said. This idea comes from the principle of “earthquake reoccurrence,” where the probability of a major earthquake happening is once every 400 to 500 years. “What happened in the past will happen in the future. It has probably been about that long since the last one occurred.”

  Plumas County is home to many very active faults, including Almanor Fault Zone, Honey Lake Fault Zone and Mohawk Valley Fault Zone. “In the last 10,000 years, dozens in our area have ruptured with an M6.5,” said Watson.

  “In Plumas and Lassen counties, there are hundreds of active volcanoes, and where there are volcanoes, there are earthquakes. We live in volcano and earthquake country; it is a very active and exciting area.

  “It is unfortunate that some of the most beautiful areas on our planet are also some of the most hazardous. This is true all over the world.

  “California has beautiful mountains and valleys, all of which can be attributed to the geology and tectonic processes. The key to living in California is to be knowledgeable that earthquakes do happen, and to be prepared for when they occur.”  

Be prepared

  “In general, earthquakes are dangerous, but they can also be fun to watch. Being able to experience a magnitude 6.7 or even 8.0 would be truly a gift, and an awesome experience for anybody. It is one of the most amazing processes this planet has to offer,” said Watson.

  “Earthquakes are rarely safe, however, and large earthquakes are devastating because they are usually accompanied with a loss of life and livelihood. Nevertheless, there are a number of things that can be done to increase earthquake awareness and preparedness.”

  The slogan “drop, cover and hold on” is well-known as a way to protect from earthquake hazards. Watson took it a step further by adding “think” as the first step in the slogan.

  “You need to back away, look at your environment and you need to think. Think about your surroundings — what can harm you and what can save you. Think about how your first move could save your life or somebody else’s,” Watson said.

  “Your ultimate goal when earth shaking starts is to move to a safe location. Your chances of survival increase dramatically if you are able to make it outside.

  Drop beneath a sturdy structure, preferably outside of a building. You need to continue to think while you are looking for a place to hide. If you are outside, look all around at things that could fall and hurt you. There are a lot of old buildings in Plumas County so watch for collapsing buildings, and, if able, hide in an area away from them.

  “Next you need to cover. Find something to guard yourself from falling debris. If you are next to a window, move far enough away that the glass doesn’t shatter all over you. Watch out for light fixtures, plants, and hanging objects that could fall down.

  Hold onto whatever is nearby. If appliances can bounce around the room, so can you.”

  What you do after the earthquake is almost as important as what you do during it. Once the shaking stops, check your health. “Make sure you are OK. If you are, then make sure others are OK, starting with any seniors who may be nearby. Also, don’t forget to check on pets,” said Watson.

  Constantly be aware of your surroundings. If you smell gas, turn off the gas valve or have someone do it for you. Avoid lighting up a cigarette in an area where there may be ruptured gas lines.

  Always keep a preparedness kit and emergency supplies on hand. This could include food, water, blankets, batteries, flashlights and other necessities.

  “After a large earthquake, there is a significant chance for large aftershocks. Be aware that they will occur. If you re-enter a damaged building, be mindful that more shaking could cause more damage.

  “Earthquakes do not last very long — usually only a few seconds to a few tens of seconds. Remember that once that brief moment of terror is gone, you will need to pick up your life and move on,” Watson said.

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