Earth Sciences

The sun “talks” to the Earth.  One channel, still poorly understood, involves the ionosphere. The ionosphere interacts magnetically with the solid Earth, reaching deep into the crust, generating forces that can trigger earthquakes. Before major earthquakes, the crust “talks” back to the ionosphere, causing perturbations. 

20 years ago computer scientist Danny Hillis thought up a monument scale slow moving mechanical clock to serve as an icon to long-term thinking. 10 years ago a first prototype was completed and put into the Science Museum of London. 5 years ago the full size clock project began design. A few months ago that project began construction. Project manager Alexander Rose will discuss the process and methods underway in the Clock of the Long Now.

 The Maunder Minimum refers to an abrupt drop in solar luminosity of less than 1% during the mid-17th Century, which had profound impacts on global climate. We may be due for another solar "grand minimum" later this century. Dr. Lubin will discuss the implications of such a grand minimum during the era of anthropogenic global warming, and will also discuss astrophysical research efforts to determine how frequently a Maunder Minimum event occurs in nature. 

 When SETI astronomer Mark Showalter is not looking up at Saturn and its rings, he prefers to spend his time looking down, preferably through the viewfinder of his underwater camera. Mark will present a slide show from his recent visit to Raja Ampat, a remote dive site in Indonesia recognized as having the highest marine biodiversity of any place on Earth. 

‘Earthquakes and Archaeology’ is an emerging field with impact on both earthquake science and archaeological and historical studies. It has been controversial as archaeologists and historians have traditionally rejected earthquakes as an important agent. But now with the advent of plate tectonics and modern instrumentation, this controversy is subsiding as we begin to offer answers to some key questions in both disciplines:

The 2007 assessment by the Intergovernmental Panel on Climate Change (IPCC) reported that uncertainty in radiative forcing of climate had been reduced compared to the previous assessment, a result of improved understanding of aerosol radiative effects. This talk shows how field experiments by NASA and collaborators, which coordinate measurements from aircraft, satellites, and Earth's surfaces, have contributed to that improved understanding. Dr.

Richard Muller and his collaborators have recently analyzed the most complete record of marine animal fossils ever compiled, the "Compendium" of Jack Sepkoski, which lists all known fossil marine animal genera back 542 million years. When the fossil diversity (number of distinct genera) is plotted, it shows a very strong 62 Myr cycle. The cycle is particularly evident in the species that endured for relatively short times, as shown in the diagram below (published in Nature, vol 434, 208-210, 10 March 2005).

Dr. Eli Silver of UC Santa Cruz will outline some of the latest research on plate tectonics. Presently, continental crust is being created in subduction zone settings (sites where tectonic plates converge) such as the Aleutians and Sumatra, due to both magmatic addition to the crust and to tectonic off-scraping. Other subduction zones (Central America, Tonga, Mariana, Peru, northern Chile, northern Japan, Kuriles) are undergoing crustal destruction through the process of subduction erosion.