Ka Hoʻomaopopo Kumu o ke Kumumanaʻo Diffraction Seismic
He manaʻo nui ka diffraction seismic ma ke kahua o ka geophysics a he kuleana koʻikoʻi kona i ka ʻimi ʻana a me ke ʻano o nā ʻano o lalo o ka honua. ʻO ke kumu, ʻo ka diffraction e pili ana i ke kaʻina hana e kūlou ai nā nalu seismic a puni nā pilikia a i ʻole e pālahalaha ma hope o ka hala ʻana ma nā puka haiki. He mea nui ka hoʻomaopopo ʻana i ka diffraction seismic no ka wehewehe pololei ʻana i ka ʻikepili seismic, no ka mea hiki iā ia ke hōʻike i nā mea he nui e pili ana i nā waiwai a me nā geometries o nā ʻano geological lalo o ka honua. Hāʻawi kēia ʻatikala i kahi ʻike piha o ke kumumanaʻo diffraction seismic, kona mau hopena, a me kāna mau noi ma ke kahua o ka geophysics.
Hoʻolauna i nā Nalu Seismic a me ka Diffraction
ʻO nā nalu seismic he mau nalu elastic e pālahalaha ana ma nā papa o ka Honua ma muli o ka hoʻokuʻu koke ʻia ʻana o ka ikehu mai nā kumu e like me nā ōlaʻi, ka hana pele, a i ʻole nā pahū ʻana i hana ʻia e ke kanaka. Hoʻokaʻawale nui ʻia kēia mau nalu i nā nalu kino (nā nalu-P a me nā nalu-S) a me nā nalu ʻili (nā nalu Rayleigh a me nā nalu Love). ʻOkoʻa ka launa pū ʻana o kēlā me kēia ʻano nalu me nā mea o lalo o ka Honua, e hāʻawi ana i ka ʻike waiwai e pili ana i nā ʻano honua a lākou e hālāwai ai.
Hana ʻia ka diffraction ke hālāwai nā nalu seismic me kahi ʻano ʻē, e like me kahi hewa, māwae, a i ʻole ka lihi i loko o ka ʻili honua. ʻAʻole e like me ka reflection a me ka refraction, e pili ana i nā nalu seismic e lele ana a kūlou paha ma waena o nā papa pōhaku like ʻole, pili ka diffraction i ka kūlou ʻana a me ka hohola ʻana o nā nalu a puni nā mea pale i liʻiliʻi a i ʻole e like ka nui me ko lākou mau nalu.
Nā Kumumanaʻo o ka Diffraction Seismic
Ua hoʻokumu ʻia ke kumumanaʻo o ka diffraction seismic ma nā loina kumu o ka mechanics nalu. E wāwahi kākou i nā ʻāpana koʻikoʻi e pili ana:
1. Ka Hoʻohālikelike Nalu:
Hoʻomalu ʻia ka laha ʻana o nā nalu seismic e ka hoʻohālikelike nalu seismic, kahi ʻano o ka hoʻohālikelike nalu elastic:
\[
\nabla^2 u – \frac{1}{v^2} \frac{\partial^2 u}{\partial t^2} = 0
\]
Maanei, hōʻike ʻo \( u \) i ke kahua neʻe ʻana, ʻo \( v \) ka wikiwiki o ka nalu, ʻo \( \nabla^2 \) ka mea hana Laplacian, a hōʻike ʻo \( t \) i ka manawa. Hōʻike kēia kaulike pehea e neʻe ai nā nalu seismic ma o nā pāpāho like ʻole a pehea lākou e launa pū ai me nā ʻano hana ma lalo o ka ʻilikai.
2. Ke Kumumanaʻo o Huygens:
ʻO ke kumumanaʻo kumu no ka hoʻomaopopo ʻana i ka diffraction ʻo ia ke kumumanaʻo o Huygens. Ke ʻōlelo nei kēia kumumanaʻo hiki ke manaʻo ʻia kēlā me kēia kiko ma kahi nalu he kumu o nā nalu poepoe lua. ʻO ka nalu hopena i kēlā me kēia manawa ma hope aku ʻo ia ka envelope o kēia mau nalu lua. Ke hālāwai nā nalu seismic me kahi keakea, hui pū kēia mau nalu lua e hana i nā ʻano diffraction.
3. Nā ʻĀpana Fresnel:
ʻO nā ʻāpana Fresnel nā ʻāpana i loko o ka ʻili honua kahi e hiki ai i nā nalu seismic ke hoʻopilikia a luku paha. He mea koʻikoʻi loa ka ʻāpana Fresnel mua (mua); ʻo nā reflections a me nā diffractions mai kēia ʻāpana e hāʻawi nui i ka ʻikepili seismic i hoʻopaʻa ʻia. ʻO ka nui a me ke ʻano o nā ʻāpana Fresnel e pili ana i nā mea e like me ka nalu a me ka mamao ma waena o ke kumu a me ka mea loaʻa.
ʻO ka Diffraction vs. Reflection a me ka Refraction
Hoʻopili pinepine ʻia ka diffraction me ka reflection a me ka refraction. Eia nō naʻe, he ʻano like ʻole a me nā hopena o kēlā me kēia hanana:
– ʻAkaʻaka: Hōʻike nā nalu ōlaʻi i nā pilina kahi i loaʻa ai nā ʻokoʻa wikiwiki, e like me ma waena o nā papa pōhaku o nā mānoanoa like ʻole. Aia ka coefficient reflection i ka ʻokoʻa impedance ma waena o nā papa.
– Refraction: Hoʻohuli a kūlou paha nā nalu seismic i ko lākou hele ʻana ma waena o nā interfaces ma nā kihi hanana maʻamau ʻole. Ma muli o ke kānāwai o Snell kēia kūlou ʻana, ka mea e pili ana i ke kihi o ka hanana i ke kihi o ka refraction ma muli o ka wikiwiki o nā media ʻelua.
– Diffraction: ʻAʻole like me ka reflection a me ka refraction, ʻaʻole hilinaʻi ka diffraction i nā ʻokoʻa wikiwiki a i ʻole nā kihi kikoʻī o ka hiki ʻana mai. Akā, hana ia i ka wā e hālāwai ai ka nalu me kahi mea pale, e alakaʻi ana i ke kūlou ʻana a me ka laha ʻana a puni ka mea pale. Hōʻike pinepine nā diffraction i nā hiʻohiʻona liʻiliʻi, ʻoi e like me nā hewa, nā haki, a i ʻole nā lihi.
Kiʻi Diffraction Seismic
ʻO ke kiʻi diffraction seismic kahi ʻenehana i hoʻohana ʻia e ʻike a nānā i ka heterogeneity subsurface i ʻike pinepine ʻia e ke kiʻi reflection maʻamau. ʻOiai ʻo ka ikehu diffraction kahi pane i nā discontinuities, hiki iā ia ke hōʻike i nā hiʻohiʻona kikoʻī e like me nā hewa, nā haki, a i ʻole nā waha liʻiliʻi.
1. Nā ʻenehana hana:
Hoʻohana ʻia nā ʻano hana seismic holomua e hoʻokaʻawale i nā hōʻailona diffraction mai nā hōʻailona reflection nui aʻe. ʻO nā ʻano maʻamau e komo pū me ke kiʻi diffraction stack a me nā ʻano neʻe i hoʻolālā kūikawā ʻia e hoʻonui i ka ikehu diffraction. Hoʻopili pinepine kēia mau ʻano hana i nā hoʻoponopono neʻe hyperbolic a me non-hyperbolic e hoʻonoho pololei i nā diffractions.
2. Nā pilikia:
Hiki ke paʻakikī ka hoʻokaʻawale ʻana a me ka wehewehe ʻana i nā diffractions ma muli o ko lākou amplitude haʻahaʻa i hoʻohālikelike ʻia me nā reflections. Eia kekahi, hiki ke uhi ʻia nā hōʻailona diffraction e ka walaʻau a i ʻole nā mea he nui, e pono ai nā ʻano kānana a me ka hana ʻana.
Nā noi ma ka ʻimi ʻana i ka honua
He nui nā noi o ke kumumanaʻo diffraction seismic i ka ʻimi ʻana i ka geophysical, e kōkua ana i ka ʻike pololei a me nā kikoʻī o ka subsurface.
1. Ka ʻIke ʻana i ka Hewa a me ka Haʻihaʻi:
He mea waiwai nui nā diffractions no ke kaha kiʻi ʻana i nā hewa a me nā haki, he mea koʻikoʻi ia no ka ʻimi ʻana i nā kumuwaiwai, me nā waihona hydrocarbon a me nā ʻōnaehana geothermal. Hiki i ka ʻike pololei ʻana i kēia mau hiʻohiʻona ke hoʻomaikaʻi i ka ʻeli ʻana a hoʻonui i ka pono hana.
2. Ke ʻano o ka waihona wai:
Hoʻokomo pinepine nā waihona wai i nā hiʻohiʻona geological paʻakikī e like me nā pinch-outs, nā kahawai, a me ka heterogeneity e hoʻopuka ai i nā diffractions. He mea nui ka hoʻomaopopo ʻana i kēia mau ʻokoʻa liʻiliʻi no ke kumu hoʻohālike pololei a me ka simulation, e alakaʻi ana i ka hoʻokele waiwai maikaʻi aʻe.
3. Ka Loiloi Pōʻino Seismic:
Kōkua ke kiʻi diffraction i ka ʻike ʻana i nā hewa i kanu ʻia a me nā hiʻohiʻona kūkulu ʻē aʻe e pili ana i nā loiloi pōpilikia seismic. He mea koʻikoʻi kēia ʻike no ka hoʻomohala ʻana i nā ʻoihana a me ka hoʻēmi ʻana i ka pilikia ma nā wahi i maʻalahi i ka ōlaʻi.
4. Nā Haʻawina ʻenekinia a me ke Kaiapuni:
Ma waho aʻe o ka ʻimi ʻana i nā kumuwaiwai, hoʻohana ʻia ka diffraction seismic i nā haʻawina ʻenekinia a me ke kaiapuni e ʻike i nā anomalies o lalo o ka ʻilikai, e like me nā hakahaka a i ʻole nā mea i kanu ʻia, i hiki ke hoʻopilikia i nā papahana kūkulu a i ʻole nā hana hoʻoponopono kaiapuni.
Panina
ʻO ka ʻike kumu o ke kumumanaʻo diffraction seismic e hāʻawi i kahi kumu no ka wehewehe ʻana a me ka hoʻohana ʻana i ka ʻikepili seismic i nā noi geophysical like ʻole. Ma ka ʻike ʻana pehea e launa pū ai nā nalu diffracted me nā hiʻohiʻona subsurface, hiki i nā geophysicists ke hoʻonui i ko lākou hiki ke palapala ʻāina a wehewehe i loko o ka Honua me ka pololei. I ka hoʻomau ʻana o ka ʻenehana kiʻi seismic a me nā ʻano hana hana, e hoʻonui ʻia nā noi a me ke koʻikoʻi o ka diffraction seismic i ka ʻimi geophysical, e hāʻawi ana i nā ʻike hohonu i nā kaʻina hana dynamic e hoʻopili ana i ko mākou honua.
