Which of these instruments is used to detect and record earthquakes?

I would hate to experience the ground motion depicted in the photo!

you know Zhang designed a seismograph 2000 years ago.. and as clever as we think we r , we still don't know how it works..kkkkk

I REMEMBER A FEW TIMES LAYING IN BED AND FELT TREMORS THAT LASTED A MINUTE. ITS A WEIRD EXPERIENCE. IM A DEEP SLEEPER, AND IT WOKE ME UP.

Qua l thong minh