I have been meaning to do this review for quite a time now. To be exact, for the past 18 months – when I bought this alarm, and most recently, about 2 months – during the April 25 earthquake in Nepal.
I live in Kathmandu, and following the M7.8 earthquake, Kathmandu has been a witness to several hundreds of small-to-medium aftershocks. Almost 10,000 people have died and disappeared following the disaster. But before I begin, let me make this clear that this alarm did not save my life. It was my house that saved me and my family.
Earthquake Detector Alert Alarm PGS047
Photo from Amazon
I bought this earthquake detector alarm PGS047 about 18 months ago from Amazon. The main reason I bought this one instead of others is that it does not require calibration. Although Nepal is a seismically active zone, the fault spreads over the entire length of the country – so it is not certain where the quake will start. That is why, it would be hard to calibrate. Ironically, now is a very good time for those in Nepal to test other earthquake alarms that need calibration. Aftershocks are still prevalent although it has been two months since.
What the alarm (says it) does
According to the product description, the alarm makes a loud sound whenever it can sense the waves. Now earthquakes come in two waves in particular – the P wave and the S wave. P waves are progressive sound waves, non-destructive, and may nor may not be heard by humans depending on its frequency, amplitude, the environment and the damping. They travel twice as fast the S waves. S waves are the destructive shock waves that are slower than P waves but cause the most destruction. This earthquake alarm has two sensors – one for P-wave and another for S wave.
How To Install The Alarm
Installing the alarm is easy. There is a plastic threaded hook inside the back of the product. Untie the thread and take it out. The alarm then can be sticked to a wall (the magic tape is supplied) or be hanged on a nail.
Two AA-size batteries are required, and come included. Insert the batteries and close the cover. When installing, make sure the water level is in the center of the black circle. Paste or hang it. That’s it! No calibration required.
The sounds made by the earthquake alarm
The loud sounds given off by the alarm are really scary, to be honest. When it senses the P wave, it plays a sound that resembles that of a vintage alarm clock. When the S waves begin, the sound turns into a loud ambulance mashed up with high frequency, high tempo bird chirping. Chirping of birds can be deemed soothing, but this mashup with the police/ambulance siren is traumatizing to your ears.
What happened on April 25 (Main shock)
The epicenter of the earthquake is denoted by the orange star. The epicenter was about 77 km west of the capital Kathmandu.
2015 Nepal Earthquake ShakeMap, by USGS
I live in Kathmandu and the epicenter of the April 25 quake was 77 km away. The earthquake alarm indeed went off but not prior to the quake. Both P waves and S waves alarm went off at the same time. And this was not “a few seconds” prior as some reviewers have said. This may be due to the fact that the rupture zone was directed towards us (directed east), and not away from us. Kathmandu became the center of the rupture zone that was about 78 km to the west and 84 km to the east. This made all the places around and including Kathmandu vulnerable to being the center of the future aftershocks. Since the epicenter will be close to us, the time difference between the two kinds of sounds given off by the alarm would decrease.
The subsequent aftershocks
2015 Nepal Earthquake main shock and aftershocks map
Following the initial shock, more than 328 aftershocks over M4.0 have been recorded, with smaller ones over 30,000 already. In the massive M7.3 aftershock on May 12, I noticed that there was around 2-3 seconds of time-difference between the two different sounds given off by the alarm. It did give us the few seconds headstart, but it was in no way enough time to run outside to safety. As I ran outside to the living room, the violent waves started shaking us. The living room is the entry/exit of our house and the safest place because it has the beams that hold the roof. It is also very dangerous to run during an earthquake, so if you find yourself in this situation, find a safe place inside the house and duck/cover your head. Avoid the stairs, and wait patiently for the shock to dampen.
Kathmandu has been the epicenter of over 7 aftershocks larger than M4.0
And each of these times, the alarm went off. The alarm began with the P wave noise and turned off after about 6-7 seconds. The magnitudes have not been large enough to trigger the S wave sensor.
Just last week on June 17, four aftershocks over M4.0 rocked Kathmandu and the surrounding areas early in the morning at 5:58 AM. The first was in Kathmandu at M4.4 and the alarm took off instantly.
Verdict and Review
In a way, the earthquake alarm PGS047 delivers what it says. If there is an earthquake you should be cautious for (powerful S waves), or if it senses the initial P-waves, the siren would go off. If the earthquake is small (M<4.0) or sometimes even less than M5.0 and you shouldn’t worry about it, it won’t go off.
However, the biggest advantage of the alarm is at night and when you are asleep. In times of deep sleep, it will easily take you several seconds to realize and wake up during the shake. By that time, it would have been too late. Even the slightest jolt of a powerful earthquake (which has powerful P waves) will trigger the alarm so you can be ready to move into a safe place, get your glasses ready, grab your phone, emergency kit and sometimes even shout out to neighbors. I give it 3.5 stars out of 5. I hope my earthquake alarm review was able to help get the right earthquake alarm device your choice in some way.