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OUR YUCAIPA | FEBRUARY 2016 13 MINOR 2.0–2.9 Felt slightly by some people. No damage to buildings. Over one million per year. 3.0–3.9 Often felt, but very rarely causes damage. Shaking of indoor objects can be noticeable. Over 100,000 per year. LIGHT 4.0–4.9 Noticeable shaking of indoor objects and rattling noises. Felt by most people in the affected area. Causes minimal damage, if any. Some objects may fall off shelves or be knocked over. 10,000 to 15,000 per year. MODERATE 5.0–5.9 Can cause damage of varying severity to poorly constructed buildings. At most, none to slight damage to all other buildings. Felt by everyone. 1,000 to 1,500 per year. STRONG 6.0–6.9 Damage to some well-built structures in populated areas. Earthquake-resistant structures survive with slight to moderate damage. Poorly designed structures receive moderate to severe damage. Felt in wider areas; up to hundreds of miles/kilometers from the epicenter. Strong to violent shaking in epicentral area. 100 to 150 per year. MAJOR 7.0–7.9 Causes damage to most buildings, some partially or completely collapse or receive severe damage. Well-designed structures are likely to receive damage. Felt across great distances with major damage mostly limited to 250 km from epicenter. 10 to 20 per year. GREAT 8.0–8.9 Major damage to buildings, structures likely to be destroyed. Will cause moderate to heavy damage to sturdy or earthquake-resistant buildings. Damaging in large areas. Felt in extremely large regions. One per year. NEAR TOTAL DESTRUCTION 9.0+ Severe damage or collapse to all buildings. Heavy damage and shaking extends to distant locations. Permanent changes in ground topography. One per 10 to 50 years. BY THE NUMBERS Matt "Carp" Carpenter, a math teacher at Yucaipa High School, helped us figure out how to determine the difference in power/strength of an earthquake. Imagine the 4.5 magnitude we had last month. If you were to experience a 5.5, it would be approximately 32 times stronger. However, because earthquake power grows exponentially, to find the estimated power of a 6.5, it would be 32 squared (32 x 32), or over 1,000 times stronger. An 8.5 would be 32 4 times stronger than a 4.5, or more than a million times stronger. Let's hope we're out of town that day. 4.5 Magnitude (the energy produced by an earthquake) of the earthquake on Jan. 5, 2016. 8.1 Magnitude of an earthquake that the southern segment of the San Andreas is capable of producing. 9.2 Magnitude of the largest earthquake recorded. It was on March 27, 1964 in Alaska. It lasted for four minutes, 38 seconds and caused 139 deaths. 6.5 Magnitude of the largest Yucaipa quake, recorded in 1992. That is over 1,000 times stronger than a 4.5. (See the sidebar below if you want to know how we determined that.) 9,365 Number of earthquakes in Yucaipa since 1931. 6.7 Magnitude of the Northridge earthquake in 1994. 57 Number of people killed in Northridge earthquake. Over 8,700 were injured and there was $40 billion in damage. 68.5% Probability Yucaipa will experience a 6.7 magnitude earthquake in the next 50 years.

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