I’ve started to writing this post with the darkness of night and the music ruin my sleepy mood, haaah, help, i’m in error mode again >_<
Okay, for some purpose, seismic methods are most accurate methods to reveal what “things” inside Earth. Are you agree? Hehe, i guess you agree…Haha
Yeah, you, please explain to us! (Eh, I’m just kidding, in some course, I always be “bad” volunteer. Am I cute?? Nooo, I guess its because I’m too over unique, sometimes lecturer get distracted by me, a troublemaker in everywhere, everytime, Lol) Sometimes I can’t explain well, huhu T.T
Okay, get focus, back to Seismic!
Sorting some references from my notes and Lillie’s book, Seismic can be define by movements of Earth’s surface sometimes small and rapid, up and down or sideways. That’s the motions. We’ll measure it as properties. What’s next? From properties, we can analyze ground motion (such as acceleration, velocity, and displacement).
Lillie said in ” Whole Earth Geophysicics” seismic technique are described by three parts: Earthquake, Seismic Refraction, and Seismic Reflection. Let see the picture below,
Earthquake, a natural sources of seismic waves
Earthquake are generated naturally of seismic waves. Seismic waves will travel inside Earth with two form, First form, Surface waves are waves which it follow Earth’s outer most regions. And second form, body waves, travel through the Earth. We get two parameters here. By learning attenuation (Q) and seismic velocity (V), we can study more properties from an earthquake (ex: hipocenter and epicenter) 😀
How about controlled sources?
Seismic waves can also generated from explosion, or other controlled-sources such as vibroseis, airgun, OBC (Ocean Bottom Cable), and so on. Its means that seismic waves by human divide by two techniques, refraction and reflection. What’s difference? Let see..
From this picture, refraction method start by sources of waves, when it travels through earth, wave will refracted and follow the nearest layer from ground. Here, we get velocity of seismic waves. We can analyze and create a model for weathered layer. How we can get more layers?
Other techniques and most commonly used for oil and gas studies is reflection seismic. It’s more penetrate than refractive. Seismometers designed for get deeper layers in ground. What’s parameters? Yaap, that’s Acoustic Impedance. It’s not only give information about seismic velocities, but also density in some layers (see the image of seismic reflection aside). Because it densities, we know petroleum systems (and unconventional too 😀 ).
Yap, I think this is enough for seismic method introductory.. Ehh you still don’t understand? (My Lord, please bless my web visitor with Your Best Giving, all of them the best people that I ever met, hehe) Okay, I’m just kidding. It’s so great experience to learn more about Earth. (I’m really distracted to being geoscientist >_<)
I’ve wish word today , wanna know? 😀
In learning, everything you do, whatever you choose, it’s up to you..
But, please sure, that subject enjoy for you.
If you enjoy,
whenever any accident happens,
no matter how bad you are,
There’s still no late
Believe, Believe that..
you’ll cheer up for keepin’ learning..n_n
(Exactly, I always agree with you, guys :D)
Nice to see you..
Always happy and joyous learning..
Dfebriana~~25/09/12 (07.46 p.m @FIB Building, University of Brawijaya)c