Measuring Earthquakes: Magnitude and Intensity

According to the global Seismographic Networks, the magnitude and intensity of earthquakes in California are not always prominent, but frequent. So is your home safe from the hazardous impact of California earthquakes?

To find out, here is a clear understanding of earthquakes and how you can protect your home from the damages:

Recording and Detecting Earthquakes

When earthquakes occur, the earth produces seismic waves. These seismic waves are digitally recorded in graphics by a seismogram that reports the wave duration and strength.

Measuring Earthquake Magnitude

Initially, wavelength peaks determine the intensity of a tremor, but that changed in recent times. Now, experts calculate it by on a scale that is more accurate in describing the effects.

Earthquake magnitude is measurable by two different scales: The Ritcher Scale and the Moment Magnitude scale. While the Richer scale was a standard scale since 1935, the Moment Magnitude scale replaced it after 1970.

  1. The Ritcher Scale: 

It got its name after the inventor Charles Ritcher, a Caltech seismologist. The scale depends on a mathematical formula that compares earthquake sizes but fails to distinguish the different earth waves. Although the Ritcher Scale gives an accurate record of earthquakes, it is effective only within 370 miles from the seismometer. It was not very effective but is still highly practical in predicting future earthquakes and potential hazards.

  1. Moment Magnitude Scale (MMS): 

Currently, most of the world seismological networks use the MMS to measure earthquake magnitude. It is used for more massive quakes as it records different types of waves, duration, and movements of rocks along the faults.

MMS measures the extent of an earthquake on the local Ritcher magnitude (ML), surface-wave magnitude (Ms), and body-wave magnitude (Mb). Because of its multi-functionality, it soon became the most effective seismogram used worldwide.

Earthquake Magnitude Classification

Seismologists classify earthquakes on the severity of the magnitude. The classification starts at “minor” for 3.0 to 3.9 magnitudes. In this class, the tremors are hardly observable or significant. Then the magnitude extends to “light,” “moderate,” “strong,” “major,” and “great” when it reaches 8.0 and above.

The intensity of the tremor and effect for each magnitude becomes more noticeable with every rising class.

Measuring Earthquake Intensity

Earthquake intensity is measured by deciphering its effects on the environment, people, and surface areas. The power differs for each location, depending on the distance from the epicenter.

There is only one way to measure earthquake intensity, but there is no fixed scale to determine it. Currently, you can only categorize on the Modified Mercalli Scale.

The Modified Mercalli (MM) Scale

The MM Scale, composed by Guiseppe Mercalli in 1902 and later modified in 1903, is commonly used in the United States. It records and categorizes earthquake impact from light tremors to catastrophic destruction, and reports in Roman numerals.

The Mercalli Scale consists of a chart that lists the intensity shaking and a description of damages in the affected areas. It is then recorded in a category on a scale of I to X.

On the scale, I represent tremors that are not felt and without physical damage anywhere. II and III represent weak shaking, and the effects are noticeable but not destructive. IV intensity or “light” means that people can physically feel it and notice their surroundings shaking or rocking.

On the other hand, moderate and strong intensity causes some damaged and may even cause a pendulum clock to stop working. Lastly, Classes VII to X intensity are highly noticeable, and the severity of the damages depends on the duration.

To check the accurate chart, you can refer to the official Mercalli scale on the USCS website.

Preparing For Severe Earthquakes

Even though earthquakes are common in California, the exact time, duration, and impact are unpredictable. Therefore, it is crucial to stay prepared at all times and plan your home settings accordingly.

To stay safe, follow these life-saving tips in case a catastrophe strikes:

  • Before it strikes, discuss re-grouping location and means of communication with your family in case you get separated.
  • Check if your home needs earthquake retrofit and if you are eligible for a grant.
  • Identify weak spots and fix potential earthquake hazards in your house.
  • Practice how to drop, cover, and hold on.
  • Pick the most sturdy furniture in your home to take shelter under and hold on until the shaking stops.
  • Know which room is the safest and make it easily accessible.
  • Pack an emergency survival kit with medical supplies, water, and non-perishable food and place it at a convenient location.
  • Identify someone outside your area for emergency calls and texts.
  • Get earthquake insurance to protect your home investment and recover any earthquake damages.

Protecting Your House From Earthquake Damages

House damages due to earthquakes can get expensive to recover. Once the injuries happen, you have to consider temporary living expenses and bounce back time. Not only is it a loss of property, but it also jeopardizes lifestyles and causes financial restrains.

So while there are many safety precautions, the best way to ensure peace is retrofitting your home. Luckily, if you are around Pasadena, retrofitters can quickly help decrease earthquake hazards at home.

Retrofitting strengthens the foundation of your house and makes it more resistant to shaking during an earthquake. Professional retrofitters can replace or repair any faulty foundation or make floor adjustments so that your home stays secure even through high-intensity tremors.

Unlike usual retrofitting, earthquake retrofit specializes in securing homes even in vulnerable areas along the California belt. The process prevents houses from sliding or collapsing during high magnitude earthquakes.

So whether you are a homeowner, contractor, real estate or insurance agent in Pasadena, preserve your property by opting for earthquake retrofit. It is the most cost-effective way to avoid property loss and increase market value in the coming years.

How to retrofit my home?

You can retrofit your home by consulting your local seismic retrofitters. Local professional companies are the best because they know the soil and understand the city planning system. Their expertise and experience will save you a lot of time and months of research or planning.

If you are from around Pasadena, you can contact your local Seismic Safety company to inspect your home. At Pasadena earthquake retrofit, you can rest assured that your property is in safe hands. All you have to do is sign up for seismic evaluation by simply telling us your address and situation.

We will give your home detailed reports and connect you to the best earthquake retrofitters and insurance companies near you. 

So next time you feel a slight tremor, you never have to panic again!

If you have any questions, don’t hesitate to give us a call at (626) 791-2300.