I am living in a weirdly active earthquake zone. There is an earthquake of Richter magnitude 3.0 and greater at least almost every week. Last year we had a 6.9 Richter earthquake which resulted about 100 dead, 1.000 injured and numerous buildings destroyed.
As you can imagine, this leaves a mental scar on almost everyone living in the city. From then on, whenever i feel like trembling, i wonder if it is just my wife rocking the sofa or we do have a real earthquake…
So i decided to make an Earthquake detector which should be fixed on a wall in the house and inform me that it is not that i am dizzy (yeah some earthquakes do that) but there is really a seismic movement. Please note that this is a prototype and i am going to try this very soon…
So, details are on my github repo.
Fritzing:
Sorry for the bad quality soldering and flux work; i am old and my eyes and hands are not what it used to be 
The MPU6050 accelerometer is used for detecting ground movements, it is a noisy accelerometer for seismic purposes but i tried it to be as cheap as possible. You don’t really need on openlog with SD card, but since that is a prototype i wanted it to record as much as possible. An RTC might also be an overkill.
So, whenever it detects a shaking greater than some value, it sends the xy and z gravitational force to MQTT sensor. If there is anyone who can contribute, he/she would be more than welcome; i am not that good at electronics nor seismic knowledge 
, hope that all the scientists out there can forgive me…