These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Announcements - Midterm: Oct 11th, 11-12:30 SAL 101 - 3 page Term Paper Due Nov, 27th - Final: Dec 18th, 8-10am SAL 101 Outline of Last Lecture I. N/A Outline of Today’s Lecture I. Definition of Science II. What exactly is the planet’s Crisis? a. Earth’s History of Crises, Back to Prehistoric Times III. Introduction to Earthquakes Today’s Lecture What is science? Science consists of two very different concepts: firstly, a collection of facts that are product of a scientific pursuit. Secondly, the process of understanding and interpreting the nature of the physical world by discovering facts and underlying principles that explain them. A mantra that some scientists choose to believe in is that the world is inherently understandable, and that we can understand it by carefully observing it. A principle of science and the scientific method is the open debates on merits of certain hypothesis. The error-correcting/falsification process is an innate aspect of scientific development. Scientists are constantly arguing, and it may often feel that because of this fact, they don’t have their act together -- science is a working process, however frustrating it may seem. Science is often conservative, which can lead to long periods of time passing before theories survive the falsification process and become commonly accepted. A prime example of this is the Theory of Evolution. Crises of a Planet The specific crises in question are technically defined as geo-punctuated events that lead to a feedback in the earth’s systems, then causing rapid changes in the environment. GEOL 108Lg Becker, Thorsten 2012 Fall Week 1 Lecture 1 August 28Global Warming, a term we have grown to use to describe these rapid changes, is in part caused by industrialization and natural resource use which speed up the earth’s processes. Crises can be defined by the diversity of lifeforms against time. Diversity specifically alludes to the number of families of species. For example, millions of years ago, we know that a mass extinction occurred rather abruptly which led to a rapid decline in the diversity of species on Earth. 443 Ma (Million Years Ago) in the Ordovician Period - Snowball Earth hypothesis The snowball earth theory suggests that the Earth’s surface became entirely frozen over, explaining enigmatic features scientists found in Earth’s geological record. 230 Ma in the End Permian Period Another period of mass extinction and large volcanic eruptions of coal and basalt, which, scientists believe, set huge areas of forests on fire. 65 Ma, the KT Boundary Event The famous extinction of the dinosaurs due to asteroid impacts, presumably in the Yucatan Peninsula. This spawned a series of huge earthquakes, atmospheric blast (which led to global fires), tsunamis, global darkness, a vast drop in temperature, and acid rain. While the sheer size of the dinosaurs made them quite susceptible to death from these factors, little mammals made use if the landscape. It is from that occurrence that humans evolved. 35 Ma, End Eocene Event Release of methane from the sediment (we currently see there to be a decline in biodiversity) How did Geologists know of these catastrophic natural events? Layers of rocks juxtaposed - measuring the diversity through the fossil records (usually there are WAY more fossils and families, then they drop suddenly). Extinctions are determined by the fossil records. Radiometric dating comes later. California Earthquakes The San Andreas fault ruptures every couple hundred years, which is why people are concerned about the plates that intersect near California moving, thus triggering a large quake. The Brawley fault zone is a complex set of faults connected to imperial fault zone. While it is impossible to stop an earthquake from happening, we have developed fairly sophisticated early warning systems allowing cities to prepare (e.g. shutting down nuclear power plants)Tohoku, Japan Earthquake This earthquake occurred offshore of Japan, caused by the pacific plate moving into the Eurasian plate - one goes underneath the other (subversion), creating thrust faults. With the Philippine/Eurasian/Pacific plates all bumping into one another, causing immediate changes in Tokyo. Often, subversion leads to tsunamis - gravitational waves with tricky properties - water depth decreases and causes huge