3-海洋地球物理-第一章-绪论(3)汇总.ppt

1 Preview 绪论 1.1 INTRODUCTION 1.2 SEABED MORPHOLOGY: A FRAMEWORK  FOR GEOPHYSICAL OBSERVATIONS 1.3 DEVELOPMENT OF MARINE GEOPHYSICS 1.3.1 Major contribution of marine geophysics to global geology 1.3.2 Impact of military science 1.3.3 Demand for petroleum and other offshore minerals 1.3.4 Availability of research vessels （船、舰）and other platforms 1.3.5 Advances in navigation 1.3.6 Internationalization of oceanography 1.3.7 Introduction of new technologies 1.3.8 Increased awareness of the human impact on oceanic environments * 第一页，编辑于星期六：十四点 十一分。 1.3 DEVELOPMENT OF MARINE GEOPHYSICS 海上地球物理测量的兴起与发展 Outline: 磁偏角测量 Measurements of magnetic declination 海上重力调查 Investigations of the Earth‘s gravity field at sea 海上电法和地震探测 electrical and seismic methods 第二次世界大战以后海洋地球物理的快速发展 The period since World War II has seen enormous advances in marine geophysics * 第二页，编辑于星期六：十四点 十一分。 1.3 DEVELOPMENT OF MARINE GEOPHYSICS 海上磁偏角测量 Magnetic declination the angle between a compass needle and geographic north ----the first geophysical observations aboard ship to provide clues about the nature of the solid Earth. Measurements of magnetic declination ----The earliest world chart showing the magnetic field at sea as lines of equal declination was published by Sir Edmond Halley (1702) following three expeditions on the naval vessel Paramore between 1698 and 1701. ---- a basis for navigation when astronomical and visual sightings on landmarks were not possible. ----declination changes with time Halley argued that this phenomenon arises from the westward rotation of the Earths deep interior with respect to its outer shell, an idea focusing on a dynamic planet that remains central to modern geomagnetism. ----To keep charts of oceanic declination up to date shipboard measurements continued from Halleys time well into this century, providing further insights into secular changes(长期变化)and the origin of the geomagnetic field. * 第三页，编辑于星期六：十四点