{"id":9643,"date":"2022-05-21T00:00:00","date_gmt":"2022-05-21T00:00:00","guid":{"rendered":"https:\/\/www.nextias.com\/current_affairs\/uncategorized\/21-05-2022\/earthquake-waves\/"},"modified":"2022-05-21T00:00:00","modified_gmt":"2022-05-21T00:00:00","slug":"earthquake-waves","status":"publish","type":"post","link":"https:\/\/www.nextias.com\/ca\/current-affairs\/21-05-2022\/earthquake-waves","title":{"rendered":"Earthquake waves"},"content":{"rendered":"<p><span style=\"font-size:13pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong><u>In News<\/u><\/strong><\/span><\/span><\/span><\/p>\n<ul>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">Scientists recently scanned a <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>rock structure <\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">that is located <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>3,000 kilometres<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>beneath Hawaii<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> and is known to<\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong> slow <\/strong><\/span><\/span><\/span><a href=\"https:\/\/www.nextias.com\/current-affairs\/29-04-2021\/earthquake-in-assam\" style=\"text-decoration:none\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#1155cc\"><strong><u>earthquake<\/u><\/strong><\/span><\/span><\/span><\/a><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong> waves.<\/strong><\/span><\/span><\/span>\n<ul>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">Researchers used<\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong> earthquake<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> or <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>seismic waves <\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">to peer into the earth\u2019s interior.<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">\u00a0The findings of the study are published in \u201c<\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>Nature Communications.\u201d<\/strong><\/span><\/span><\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p><span style=\"font-size:13pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong><u>More findings:<\/u><\/strong><\/span><\/span><\/span><\/p>\n<ul>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">The rock structure is what is called an<\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong> \u2018ultra-low velocity zone\u2019<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">.\u00a0<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">These are thought to be<\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong> hundreds of kilometres wide and tens of kilometres thick.\u00a0<\/strong><\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">It is found that the speed of the quake waves travelling through the base could be <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>40 percent slower<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> than the surrounding regions.<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">The <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>Hawaiian structure<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> is <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>one of many such zones<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> present in various pockets of the planet.<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:disc\"><span style=\"font-size:13pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong><u>Possible reasons for slow <\/u><\/strong><\/span><\/span><\/span><a href=\"https:\/\/www.nextias.com\/current-affairs\/29-04-2021\/earthquake-in-assam\" style=\"text-decoration:none\"><span style=\"font-size:13pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#1155cc\"><strong><u>earthquake <\/u><\/strong><\/span><\/span><\/span><\/a><span style=\"font-size:13pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong><u>waves:<\/u><\/strong><\/span><\/span><\/span>\n<ul>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">Some portions of the earth\u2019s interiors can act as <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>speed bumps<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">. For instance, <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>hotter areas slow down seismic wave<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">s, allowing scientists to find clues on what makes up the interior layers of the planet.<\/span><\/span><\/span>\n<ul>\n<li style=\"list-style-type:square\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">The wave speeds <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>slow down by 20 percent<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> throughout the entire zone. But towards the base, it is probably twice as slow.<\/span><\/span><\/span><\/li>\n<\/ul>\n<\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">This slowdown could be due to its <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>dense iron content<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">.\u00a0<\/span><\/span><\/span>\n<ul>\n<li style=\"list-style-type:square\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">The <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>increase in iron, and to a lesser degree the high temperatures of these zones<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> (they sit on top of the hot core),<\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong> cause the slow velocities of waves<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">.<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:square\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>The iron-rich material in the zone-<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">\u00a0<\/span><\/span><\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<ul>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">could be a remnant of <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>ancient rocks from Earth\u2019s early history<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">.<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">Alternatively, the<\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong> iron might be leaking from the core<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> by some unknown means.<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">The <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>zone\u2019s origins<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> can be traced to around four billion years ago when the Earth was an infant.<\/span><\/span><\/span>\n<ul>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">Around this time, scientists believe a <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>Mars-sized rock crashed into the earth<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">, raising the planet\u2019s temperatures and creating a <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>magma ocean<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">.<\/span><\/span><\/span><\/li>\n<\/ul>\n<\/li>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">At some point, the iron materials likely descended deep into the interiors, forming pockets called the <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>ultra-low-velocity zones<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">, according to the study.<\/span><\/span><\/span><\/li>\n<\/ul>\n<p>\u00a0<\/p>\n<p><a href=\"https:\/\/www.nextias.com\/current-affairs\/29-04-2021\/earthquake-in-assam\" style=\"text-decoration:none\"><span style=\"font-size:13pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#1155cc\"><strong><u>Earthquake <\/u><\/strong><\/span><\/span><\/span><\/a><span style=\"font-size:13pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong><u>waves<\/u><\/strong><\/span><\/span><\/span><\/p>\n<p><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">These are of 2 types \u2013 <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>body waves and surface waves<\/strong><\/span><\/span><\/span><\/p>\n<ul>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>Body waves:<\/strong><\/span><\/span><\/span>\n<ul>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">Generated due to the <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>release of energy at the focus<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> and move in all directions travelling through the body of the earth. Hence, the name \u2013 body waves.<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">Travel <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>only through the interior of the earth<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">.<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>Faster than surface waves<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">.<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">There are 2 types of body waves: <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>P- primary waves and S-secondary waves<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">.<\/span><\/span><\/span>\n<ul>\n<li style=\"list-style-type:square\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">P waves travel through <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>gaseous, liquid and solid materials <\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">whereas S waves travel<\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong> only through solid materials.<\/strong><\/span><\/span><\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<ul>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>Surface Waves:<\/strong><\/span><\/span><\/span>\n<ul>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">When the <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>body waves interact with surface rocks<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">, a new set of waves is generated called surface waves.\u00a0<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">These waves <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>move along the earth&#8217;s surface.<\/strong><\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">Surface waves are<\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong> transverse waves<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> in which particle movement is perpendicular to the wave propagation. Hence, they create <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>crests and troughs<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> in the material through which they pass.<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">They are the<\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong> most damaging <\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">waves.\u00a0<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">2 common surface waves are <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>Love waves <\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">and <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>Rayleigh waves.<\/strong><\/span><\/span><\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<ul>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>Speed of different Waves<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> in <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>descending order: Primary Waves > Secondary Waves > Love Waves > Rayleigh Waves.<\/strong><\/span><\/span><\/span><\/li>\n<\/ul>\n<p><span style=\"font-size:13pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong><u>Emergence of Shadow Zone\u00a0<\/u><\/strong><\/span><\/span><\/span><\/p>\n<ul>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">Earthquake waves get recorded on seismo- graphs located at far-off locations.\u00a0<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">However, there exist<\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong> some specific areas where the waves are not reported.<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> Such a zone is called the \u2018shadow zone\u2019.<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">P and S waves radiate spherically away from an earthquake&#8217;s hypocenter (or focus) in all directions and return to the surface by many paths. However,<\/span><\/span><\/span>\n<ul>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>P waves<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> are refracted by the liquid outer core and are not detected between 105\u00b0 and 145\u00b0<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>S waves<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> cannot pass through the liquid outer core and are not detected beyond 103\u00b0<\/span><\/span><\/span><\/li>\n<\/ul>\n<\/li>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">Thus, a <\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>zone between 105\u00b0 and 145\u00b0 from the epicentre (approximately)<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> is identified as the<\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong> shadow zone for both the types of waves.<\/strong><\/span><\/span><\/span><\/li>\n<\/ul>\n<p>\u00a0<\/p>\n<p style=\"text-align:center\"><span style=\"font-size:13pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong><u><img decoding=\"async\" src=\"https:\/\/lh6.googleusercontent.com\/OP7_cTNIuJrc_IsVk9_WLnkQoIq0Ay-oPvA9KeFQb7HS0EZedrFrN5BjvEemKYnFC-pzZl5zzKozs3hdAFFcvyrg0wpkATKOP1TcYVqddp9gsRpHafD26kY_JgOqdCsB7a1aNciKBXwbwQ65-A\" style=\"height:249px; width:350px\" \/><\/u><\/strong><\/span><\/span><\/span><\/p>\n<p style=\"text-align:center\"><span style=\"font-size:13pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong><u><img decoding=\"async\" src=\"https:\/\/lh4.googleusercontent.com\/895_SSQ4YK1nOLtNd2prK0hS-eYxzQs4WrGZSwisda8VIGXRkhTecJO6n64xDQBz-7678XbU4-9l8obj-cOLZHvoWgipVQ3H3ui_LHpc3NhkVsTtbQ4Z78C8DnD-8tWNGBBjj5eJHKpijvCqmQ\" style=\"height:254px; width:326px\" \/><\/u><\/strong><\/span><\/span><\/span><\/p>\n<div>\n<table cellspacing=\"0\" style=\"border-collapse:collapse; border:none; table-layout:fixed; width:624px\">\n<tbody>\n<tr>\n<td style=\"background-color:#fff2cc; border-bottom:1px solid #000000; border-left:1px solid #000000; border-right:1px solid #000000; border-top:1px solid #000000; vertical-align:top\">\n<p><span style=\"font-size:13pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong><u>The layers of Earth\u2019s interior<\/u><\/strong><\/span><\/span><\/span><\/p>\n<ul>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>The Crust\u00a0<\/strong><\/span><\/span><\/span>\n<ul>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">It is the outermost solid part of the earth.\u00a0<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">It is brittle in nature.\u00a0<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">The thickness of the crust varies under the oceanic and continental areas.\u00a0<\/span><\/span><\/span>\n<ul>\n<li style=\"list-style-type:square\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">The oceanic crust is thinner compared to the continental crust.\u00a0<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:square\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">The continental crust is thicker in the areas of major mountain systems.<\/span><\/span><\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>The Mantle\u00a0<\/strong><\/span><\/span><\/span>\n<ul>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">It is the portion of the interior beyond the crust.\u00a0<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>The asthenosphere<\/strong><\/span><\/span><\/span>\n<ul>\n<li style=\"list-style-type:square\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">The upper portion of the mantle is called the asthenosphere.\u00a0<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:square\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">The word \u2018astheno\u2019 means weak.<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:square\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">It is the main source of magma that finds its way to the surface during volcanic eruptions.<\/span><\/span><\/span><\/li>\n<\/ul>\n<\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">The lower mantle extends beyond the asthenosphere.\u00a0<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>The lithosphere\u00a0<\/strong><\/span><\/span><\/span>\n<ul>\n<li style=\"list-style-type:square\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">The crust and the uppermost part of the mantle are called lithosphere.\u00a0<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:square\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">It is in a solid state.<\/span><\/span><\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<li style=\"list-style-type:disc\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>The core\u00a0<\/strong><\/span><\/span><\/span>\n<ul>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">The earthquake wave velocities helped in understanding the existence of the core of the earth.\u00a0<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">The outer core is in a liquid state while the inner core is in a solid state.\u00a0<\/span><\/span><\/span><\/li>\n<li style=\"list-style-type:circle\"><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\">The core is made up of very heavy material mostly composed of nickel and iron.\u00a0<\/span><\/span><\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p style=\"text-align:center\"><span style=\"font-size:13pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><img decoding=\"async\" src=\"https:\/\/lh3.googleusercontent.com\/UuHqQS_iggF4-K36VwtYFWRmAV9Zi9yAbNBypU2Z_wAKb9Vd4xS16VPR9_-0yPxfRQb-BKFzvczhNAipeZA_46tRh8amF1ey9sCvyFVz8kLIGp_Wn-tpeX5PrlFBtRqnBK96-nwMXSTvny9IjA\" style=\"height:216px; width:291px\" \/><\/span><\/span><\/span><\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"><strong>Source:<\/strong><\/span><\/span><\/span><span style=\"font-size:12pt\"><span style=\"font-family:'Book Antiqua',serif\"><span style=\"color:#000000\"> DTE; NCERT<\/span><\/span><\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>In News Scientists recently scanned a rock structure that is located 3,000 kilometres beneath Hawaii and is known to slow earthquake waves. Researchers used earthquake or seismic waves to peer into the earth\u2019s interior. \u00a0The findings of the study are published in \u201cNature Communications.\u201d More findings: The rock structure is what is called an \u2018ultra-low [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":9644,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[21],"tags":[160,164,25],"class_list":["post-9643","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-current-affairs","tag-earthquakes","tag-geomorphology","tag-gs1"],"acf":[],"jetpack_featured_media_url":"https:\/\/wp-images.nextias.com\/cdn-cgi\/image\/format=auto\/ca\/uploads\/2023\/07\/303506Screenshot_6.png","_links":{"self":[{"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/posts\/9643","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/comments?post=9643"}],"version-history":[{"count":0,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/posts\/9643\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/media\/9644"}],"wp:attachment":[{"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/media?parent=9643"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/categories?post=9643"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/tags?post=9643"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}