Query: Duffy pointed out that his chart was from a single tide gauge station, near San Francisco, and that sea levels rise at different rates around the world

Relevant passages:
San Francisco Bay <=SEP=> San Francisco Bay is a shallow estuary in the U.S. state of California . It is surrounded by a contiguous region known as the San Francisco Bay Area ( often simply `` the Bay Area '' ) , dominated by the large cities San Francisco , Oakland , and San Jose .   San Francisco Bay drains water from approximately 40 percent of California . Water from the Sacramento and San Joaquin rivers , and from the Sierra Nevada mountains , flow into Suisun Bay , which then travels through the Carquinez Strait to meet with the Napa River at the entrance to San Pablo Bay , which connects at its south end to San Francisco Bay . It then connects to the Pacific Ocean via the Golden Gate strait . However , this entire group of interconnected bays is often called the San Francisco Bay .   The bay was designated a Ramsar Wetland of International Importance on February 2 , 2013 .

1906 San Francisco earthquake <=SEP=> The 1906 San Francisco earthquake struck the coast of Northern California at 5:12 a.m. on April 18 with an estimated moment magnitude of 7.8 and a maximum Mercalli intensity of XI ( Extreme ) . Severe shaking was felt from Eureka on the North Coast to the Salinas Valley , an agricultural region to the south of the San Francisco Bay Area . Devastating fires soon broke out in the city and lasted for several days . As a result , about 3,000 people died and over 80 % of the city of San Francisco was destroyed . The events are remembered as one of the worst and deadliest natural disasters in the history of the United States . The death toll remains the greatest loss of life from a natural disaster in California 's history and high in the lists of American urban disasters .

Tide <=SEP=> Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth .   The times and amplitude of tides at any given locale are influenced by the alignment of the Sun and Moon , by the pattern of tides in the deep ocean , by the amphidromic systems of the oceans , and the shape of the coastline and near-shore bathymetry ( see Timing ) . Some shorelines experience a semi-diurnal tide -- two nearly equal high and low tides each day . Other locations experience a diurnal tide -- only one high and low tide each day . A `` mixed tide '' -- two uneven tides a day , or one high and one low -- is also possible .   Tides vary on timescales ranging from hours to years due to a number of factors . To make accurate records , tide gauges at fixed stations measure water level over time . Gauges ignore variations caused by waves with periods shorter than minutes . These data are compared to the reference ( or datum ) level usually called mean sea level .   While tides are usually the largest source of short-term sea-level fluctuations , sea levels are also subject to forces such as wind and barometric pressure changes , resulting in storm surges , especially in shallow seas and near coasts .   Tidal phenomena are not limited to the oceans , but can occur in other systems whenever a gravitational field that varies in time and space is present . For example , the solid part of the Earth is affected by tides , though this is not as easily seen as the water tidal movements .