Seismic Alarm and Monitoring System can save lives during earthquakes

Historically, the Philippines as one of the countries in the Pacific ring of fire remains to be at loss when it comes to responding to earthquakes. The Philippines continues to suffer unimaginable loss of thousands of lives and billions of properties due to earthquake.

On July 16, 1990 a catastrophic earthquake of 7.7 magnitude with epicenter near Rizal hit Luzon, causing 1, 666 casualties and extensive damage. The death and devastation induced by the tremors were accompanied by the collapse of buildings and infrastructure facilities. From July 1990 to October 1991, the damage caused by the quake, volcanic eruption and rains had been estimated at several billion US dollars. On October 15, 2013, an earthquake with 7.2 Magnitude struck the island provinces in the Visayas region. 222 were found dead and 976 were injured. More than 73,000 structures were affected with 14,500 of them totally ruined. It was the deadliest earthquake after 23 years when a similar magnitude hit Cabanatuan in 1990.

 Figure 1 - Hyatt Hotel before the earthquake in 1990

Figure 2 - Hyatt Hotel after the earthquake in 1990

As of December 31, 2013, the Philippines has experienced two (2) earthquakes that day, five (5) earthquakes in the past seven days, 16 earthquakes in the past month and 142 earthquakes for the year 2013. Given that the Philippines has that much seismic activity, it would have seem that the country is prepared for the worst that is to come as brought about by the active seismic activity in which the archipelago is located.

Although no technology has been created yet to predict earthquakes, seismologist Richard Allen said in a National Geographic article that an earthquake early warning system may provide the public with crucial seconds to prepare for severe shaking and save their lives.

This earthquake warning device records peak ground acceleration (PGA), velocity (PGV), ground displacement (PGD) and spectral intensity (SI) and emit warning signal when the earthquake ground motion is so strong.

Cebu businesses, manufacturers, and building owners are set to acquire the earthquake monitoring system (i.e. S200 and S401-PSCR) manufactured by MESEI of Japan. The companies were convinced of the effectiveness and efficacy of seismic equipment when it recorded all of the earthquake events in December 2013.

Locating earthquakes

Locating earthquakes

By looking at the seismograms from different recording stations we can find out the epicentre of the earthquake. The signals arrive first at the closest station and last at the one furthest away.

The time difference between the P- and S-waves tells us the distance the earthquake is from the seismograph. By measuring this at three stations we can work out where the epicentre is.

We need measurements from at least three stations to find the epicenter. The intersection of the circles whose radius is equivalent to the distance from the earthquake gives the epicenter.

Please note that the information here were taken from British Geological Survey.

Magnitude and Intensity of Earthquake

What is the difference between magnitude and intensity?

Magnitude is a measure of earthquake size and remains unchanged with distance from the earthquake.

Intensity, however, describes the degree of shaking caused by an earthquake at a given place and decreases with distance from the earthquake epicentre.

We can, therefore talk about a magnitude 5.4 ML (Moment Magnitude) event with intensity of 6 EMS European macroseismic scale) in the epicentral area, on the Lleyn Peninsula, but intensity 3 EMS at Carlisle.

Magnitude measurement requires instrumental monitoring for its calculation, however, assigning an intensity requires a sample of the felt responses of the population. This is then graded according to the EMS intensity scale.

For example, Intensity 1, Not felt, 2, Scarcely perceptible, 3, weak, felt by a few, up to 12 assigned for total devastation.

Study of intensity and the production of isoseismal maps, contouring areas of equal intensity, is particularly important for the study of earthquakes which occurred prior to instrumental monitoring.

The article above was taken from British Geological Survey FAQ webpage.

Triangle of life theory

Triangle_of_life_theory was featured in DZMM website.

The story started with:

Binasag ng Philippine Institute of Volcanology and Seismology (Phivolcs) ang nosyon ng paggamit ng "triangle of life" sa pagtama ng lindol.

Understanding Intensity Scale and the sense of feeling

The common Intensity and Magnitude Scales used all over the world. See blog on Intensity and Magnitude

The image on the left shows the Shindo Scale used in Japan. The Scale ranges from Shindo 1 up to Shindo 7. The Shindo scale steps are as follows: Shindo 1 Shindo 2 Shindo 3 Shindo 4 Shindo 5 - lower Shindo 5 - upper Shindo 6 - lower Shindo 6 - upper Shindo 7 Shindo 7 is the most devastating earthquake. Shindo scale intensity is based on the instrument recorded value in terms of gals. One of this instrument is the combination of SW-72R with SW-74SI. Please see our other page about Earthquake Alarm / Monitoring System.

Mercalli Scale

European Macroseismic Intensity Scale

1. Not felt — detected by seismic instruments only
2. Very weak — felt by very few people
3. Weak — felt by a few people indoors
4. Noticed by many people, windows and doors rattle
5. Strong — some small objects fall over
6. Slightly damaging — objects fall off shelves
7. Damaging — parts of chimneys fall
8. Very damaging — large cracks in walls
9. Destructive — some houses collapse
10. Very destructive — many houses collapse
11. Devastating — most ordinary buildings collapse
12. Completely devastating — practically all structures above and below ground are heavily damaged or destroyed

Earthquake Sensor (SW-72R and SW-74SI)

Earthquake Alarm/Monitoring System

The Earthquake Alarm/Monitoring System is composed of two major equipment and these are:

• SW-72R Seismic Monitor
• SW-74SI Seismic Processor

SW-72R Seismic Monitor	SW-74SI Seismic Processor

  

SW-74SI which is equipped with 10-step alarm output and SI value output is an advanced version of the model SW-74.

SW-72R is the device that actually measure the ground intensity and shows the value in gals. It can operate with or without the SW-74SI. However, for alarm and recording purposes, SW-74SI is required.

The SI value, known as “velocity response spectrum”, is one of the standards that is used to express the earthquake's destructive power against structures, i.e. buildings, infrastructures, etc.

How does it provides an alarm for the earthquake activity?

The integrated units (i.e. combined SW-72R and SW-74SI) when combined, will allow us to know of the on-going earthquake eventhough we haven't feel it. This piece of tool shall provide us ample time to take cover for safety.

Below are some configuration data that can be used to program the unit so it will provide the alarm (either bell, or voice announcement) depending on the earthquake Intensity.

Why do we need use this equipment?

We need the equipment for our safety. The equipment is capable of providing the necessary alarm or announcement so we can react accordingly similar to the ones used by Fire Alarm.

With this alarm, we will be able to know that the earthquake is happening. 

Photos of 7.2 Magnitude Cebu and Bohol Earthquake

They say that pictures is worth a thousand words. In line with that, here are some photographs taken  today (October 15,2013) by different people and was posted in Facebook and Twitter.

From Facebook

Photos of Robert Michael Poole

Tokyo drastic photographs like the one below. Check his twitter for more.

Earthquake Alarm and Measurement

The Earthquake

We do not know when and where earthquake will struck. However, with the technology of today, at least we can readily know of the earthquake activity even if the intensity is below the grasps of our senses and feelings.

Let us have some earthquake short tutorial

Did you know that during an earthquake, there is normally 2 waves that arrives. The first one is called a P-Wave, and the 2nd and most destructive is the S-Wave. Graph below illustrates the P-wave and S-wave arrival. See British Geological Survey for more details.

Three of this reading from different geographical locations determine the epicenter of the earthquake. See the blog on locating the earthquake

As a summary, you don't want to be in a dangerous situation when S-Wave (or the strongest) comes.

Article below shows how earthquake is measured. This article was taken from British Geological Survey Website

• A seismogram is a record of the seismic waves from an earthquake.

• A seismograph or seismometer is the measuring instrument that creates the seismogram.

• Almost all seismometers are based on the principle of inertia: a suspended mass tends to remain still when the ground moves.

• The relative motion between the suspended mass and the ground will then be a measure of the ground’s motion.

• On a seismogram from an earthquake, the P-wave is the first signal to arrive, followed by the slower S-wave, then the surface waves.

• The arrival times of the P- and S-waves at different seismographs are used to determine the location of the earthquake.

• Given that we know the relative speed of P- and S-waves, the time difference between the arrivals of the P- and S-waves determines the distance the earthquake is from the seismograph.

Measuring Earthquake

Earthquake is represented by several measurements in magnitude and intensity. The most common are:

• Richter Scale
• Mercalli Scale
• Shindo Scale

Detailed history of the earthquake scale can be found in Wikipedia.

The Shindo intensity scale is widely used in Japan which is based on instrument readings. The basis of unit is based on gals, centimeter per second square, or g.

0.01 m/s² = 1 Gal 

1 cm/s² = 1 Gal

1 g = 981 Gal

1 g = 9.81 m/s²  

Read the article in Wikipedia regarding the Peak Ground Acceleration, relationship of Instrumental Scale and to the what people felt, and correlation with Mercalli Scale. Below are the Mercalli Scales, corresponding g reading, and the perceived effect.

This units are used in building construction as a guide to the building earthquake resistance, and as a reference data of Structural Engineers to declare the structural soundness of the buildings.

Measurement and Alarm

Awhile ago, an earthquake struck Cebu Philippines with a magnitude of 7.2 in the Richter Scale. See how the magnitude 7.2 is perceived in youtube below:

The magnitude 7.2 in Richter Scale is equivalent to Mercalli VIII with a g of 0.34 to 0.65 as shown in the table below

Instrumental Intensity	Acceleration (g)	Velocity (cm/s)	Perceived Shaking	Potential Damage
I	< 0.0017	< 0.1	Not felt	None
II-III	0.0017 - 0.014	0.1 - 1.1	Weak	None
IV	0.014 - 0.039	1.1 - 3.4	Light	None
V	0.039 - 0.092	3.4 - 8.1	Moderate	Very light
VI	0.092 - 0.18	8.1 - 16	Strong	Light
VII	0.18 - 0.34	16 - 31	Very strong	Moderate
VIII	0.34 - 0.65	31 - 60	Severe	Moderate to heavy
IX	0.65 - 1.24	60 - 116	Violent	Heavy
X+	> 1.24	> 116	Extreme	Very heavy

Note: Table taken from Wikipedia (URL: http://en.wikipedia.org/wiki/Peak_ground_acceleration)

As a summary, the reading in Cebu are as approximately follows based on different scale

Oct 15,2013, magnitude 7.2 in Richter Scale. Equivalent to:

• Mercalli VIII
• g 0.34 - 0.65
• velocity of 31 - 60
• Gals 333.54 to 637.65
• Shindo Scale 6 upper

Alarms / Announcement, AllTechSolution Capability

In the beginning, we explained that there are 2 waves. Sometimes, the first wave cannot be felt, but it doesn't mean that the 2nd wave will not be destructive.

What happened in the video is that the 2nd wave was proven to be destructive because of the number of buildings that fell down. Just imagine if a number of people were in the building and crushed to the ground like the one that happened in Baguio City Philippines in 1990. That would be tragic on the 2nd time around.

We have had our taste of experience in the 1990 event, and this became our guiding principle to bring in the right product to the people for safety purposes.

AllTechSolution has brought a product to Philippines known as Earthquake Alarm/Monitoring System. See photo below:

The integrated unit is combination of SW-72R Seismic Monitor and SW-74 Seismic Processor. The SW-72R Seismic Monitor continuously scan the ground acceleration at 100 times a second. The data provided by SW-72R is a number that a layman can easily understand.

When an earthquake occurs, it shakes the ground. This shaking is detected by the SW-72R at 100 times a second at 16 bits resolution. Observing the SW-72R and SW-74SI, you will notice that a number is shown in the screen of both device. Assuming it shows the number 24, it means that the ground is shaking at 24 gals.

This numbers allows you to actually sound the alarm manually or automatically issue a voice notification (similar to the advance fire alarm system) based on the pre-determined alarm set-point to empower people to choose between life and death situation.

Considering that buildings might collapsed, a "second" of time to react (or take cover for safety) will mean a lot especially when life is at stake.

As shown in the video, people reacted late because of non-notification. It would be tragic if they are in the buildings that collapsed. Thank God that they are not.

With the solution we have, the benefits can be as follows:

• can save more lives
• can be used in mitigation of facilities by shortening the inspection time
• data can be used as a reference data to make sure that the facility is structurally sound
• Utilities such as power can be restored right away
• Airport runways can easily be declared safe at earliest time, etc.

Those are the kinds of benefits that pays that the equipment itself. That without our equipment in the field, the loss of time for non-operation of industrial facilities, schools, offices, Malls, etc. will more.

Going back in time in 1990, a lot of people could have saved their own lives only if we have the same technology that we these days. It's been 23 years, and I believe that people that people are more aware of the dangers.

I do hope that Government agencies have learned the lessons from the past, is currently working to provide better service, so we - the Pilipino people, can have a better future.

Mabuhay ang Pilipino!!!

I used to see this in the TV and street advertisement before - "be honest even if others are not, cannot, will not". I just hope everybody will for the better Philippines.