More than a hundred years ago an extraordinary mechanism was found by sponge divers at the bottom of the sea near the island of Antikythera. It astonished the whole international community of experts on the ancient world. Was it an astrolabe? Was it an orrery or an astronomical clock? Or something else?
For decades, scientific investigation failed to yield much light and relied more on imagination than the facts. However research over the last half century has begun to reveal its secrets. The machine dates from around the end of the 2nd century . and is the most sophisticated mechanism known from the ancient world. Nothing as complex is known for the next thousand years. The Antikythera Mechanism is now understood to be dedicated to astronomical phenomena and operates as a complex mechanical "computer" which tracks the cycles of the Solar System .
For mechanisms calculated from first-motion directions as well as some methods that model waveforms, there is an ambiguity in identifying the fault plane on which slip occurred from the orthogonal, mathematically equivalent, auxiliary plane. We illustrate this ambiguity with four examples (B). The block diagrams adjacent to each focal mechanism illustrate the two possible types of fault motion that the focal mechanism could represent. Note that the view angle is 30-degrees to the left of and above each diagram. The ambiguity may sometimes be resolved by comparing the two fault-plane orientations to the alignment of small earthquakes and aftershocks. The first three examples describe fault motion that is purely horizontal (strike slip) or vertical (normal or reverse). The oblique-reverse mechanism illustrates that slip may also have components of horizontal and vertical motion.
The animations were produced using Microsoft's Visual J++ . In my opinion, J++ at is still very much a beta (or should I say my beta noire). It's reintroduced what I call "elevator shaft programming," when an innocent or stupid mistake seizes the system up, the debugger won't load, and the power switch is the only way out. A lot like assembly language programming without an assembler. Real "elevator shaft programming" is writing programs in machine language to control machines or industrial processes. At least with J++, nobody gets killed.