Pacific Time Zone being aligned with the 120th meridian. The differences in local times were substantial, with San Francisco at 122.43 W and San Diego at 117.10 W, the difference between the two would be around 22 minutes (4 minutes per degree). At least one individual reported foreshock times that varied by as much as half an hour when speaking to two different newspapers. The firsthand reports were most abundant for the shocks felt at 1, 2, and 4 hours before the main shock which were later labeled the predawn, dawn, and sunrise shocks. The predawn event shook residents of San Francisco (MMI II – III), San Jose (MMI IV), and Santa Cruz (MMI IV). The dawn shock was felt in those locales plus Fort Tejon and possibly the Carrizo Plain. The sunrise shock was felt in San Francisco (MMI III), Monterey (MMI IV), and Visalia (MMI II – III). Sacramento and Los Angeles did not report any of these events. Several mid-twentieth-century earthquakes had similar felt reports to the dawn and sunrise shocks, and with close inspection, Sieh theorizes that both events were local to coastal central California, probably between Point Conception and Monterey. Also, during that period, no central California earthquake with a magnitude of less than five had a felt area as large as the two foreshocks, while events larger than magnitude six have had "somewhat larger" felt areas, so it could be said that the foreshocks most likely were between magnitude five and six. Parkfield earthquakes occurred with exceptionally regular intervals (between 20 and 30 years) between 1857 and 1966. Sieh studied four of these events (1901, 1922, 1934, and 1966) and found that they helped to determine the southeast boundary for the origination of the dawn foreshock. The coverage and intensities of felt reports for that earthquake show a solid resemblance to the Parkfield events. Only one of the four Parkfield events was not felt further southeast than the dawn shock, so Sieh concluded that if the San Andreas was the source of the event, then it was reasonable to assume that the Parkfield to Cholame stretch of the fault was responsible for producing the dawn felt intensities, though the San Andreas is not the only possible source for the dawn event. For example, the November 22, 1952, magnitude six Bryson earthquake "nearly duplicates" the felt reports. That event may have occurred west of the