An earthquake is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from those that are so weak that they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume. The word tremor is also used for non-earthquake seismic rumbling.
A tsunami is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explosions above or below water all have the potential to generate a tsunami. Unlike normal ocean waves, which are generated by wind, or tides, which are in turn generated by the gravitational pull of the Moon and the Sun, a tsunami is generated by the displacement of water from a large event.
Crescent City is the only incorporated city in Del Norte County, California; it is also the county seat. Named for the crescent-shaped stretch of sandy beach south of the city, Crescent City had a total population of 6,673 in the 2020 census, down from 7,643 in the 2010 census. The population includes inmates at Pelican Bay State Prison, also within the city limits, and the former census-designated place Crescent City North annexed to the city. The city is also the site of the Redwood National Park headquarters, as well as the historic Battery Point Light. Due to the richness of the local Pacific Ocean waters and the related catch, and ease of access, Crescent City Harbor serves as home port for numerous commercial fishing vessels.
Point Arena, formerly known as Punta Arena is a small coastal city in Mendocino County, California, United States. Point Arena is located 32 miles (51 km) west of Hopland, at an elevation of 118 feet (36 m). The population was 460 at the 2020 census, making it one of the smallest incorporated cities in the state.
The 1964 Alaskan earthquake, also known as the Great Alaskan earthquake and Good Friday earthquake, occurred at 5:36 PM AKST on Good Friday, March 27. Across south-central Alaska, ground fissures, collapsing structures, and tsunamis resulting from the earthquake caused about 131 deaths.
A storm surge, storm flood, tidal surge, or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low-pressure weather systems, such as cyclones. It is measured as the rise in water level above the normal tidal level, and does not include waves.
A seawall is a form of coastal defense constructed where the sea, and associated coastal processes, impact directly upon the landforms of the coast. The purpose of a seawall is to protect areas of human habitation, conservation, and leisure activities from the action of tides, waves, or tsunamis. As a seawall is a static feature it will conflict with the dynamic nature of the coast and impede the exchange of sediment between land and sea.
On 26 December 2004, at 07:58:53 local time (UTC+7), a major earthquake with a magnitude of 9.1–9.3 struck with an epicentre off the west coast of northern Sumatra, Indonesia. The undersea megathrust earthquake, known by the scientific community as the Sumatra–Andaman earthquake, was caused by a rupture along the fault between the Burma Plate and the Indian Plate, and reached a Mercalli intensity up to IX in some areas.
The Embarcadero is the eastern waterfront of Port of San Francisco and a major roadway in San Francisco, California. It was constructed on reclaimed land along a three mile long engineered seawall, from which piers extend into the bay. It derives its name from the Spanish verb embarcar, meaning "to embark"; embarcadero itself means "the place to embark." The Central Embarcadero Piers Historic District was added to the National Register of Historic Places on November 20, 2002.
The Port of San Francisco is a semi-independent organization that oversees the port facilities at San Francisco, California, United States. It is run by a five-member commission, appointed by the Mayor and approved by the Board of Supervisors. The Port is responsible for managing the larger waterfront area that extends from the anchorage of the Golden Gate Bridge, along the Marina district, all the way around the north and east shores of the city of San Francisco including Fisherman's Wharf and the Embarcadero, and southward to the city line just beyond Candlestick Point. In 1968 the State of California, via the California State Lands Commission for the State-operated San Francisco Port Authority, transferred its responsibilities for the Harbor of San Francisco waterfront to the City and County of San Francisco / San Francisco Harbor Commission through the Burton Act AB2649. All eligible State port authority employees had the option to become employees of the City and County of San Francisco to maintain consistent operation of the Port of San Francisco.
The 1957 Andreanof Islands earthquake occurred at 04:22 local time on March 9 with a moment magnitude estimated between 8.6 and 9.1 and a maximum Modified Mercalli intensity of VIII (Severe). It occurred south of the Andreanof Islands group, which is part of the Aleutian Islands arc. The event occurred along the Aleutian Trench, the convergent plate boundary that separates the Pacific Plate and the North American plates near Alaska. A basin-wide tsunami followed, with effects felt in Alaska and Hawaii, and strong waves recorded across the Pacific rim. Total losses were around $5 million.
An earthquake occurred on July 17, 2006 at along a subduction zone off the coast of west and central Java, a large and densely populated island in the Indonesian archipelago. The shock had a moment magnitude of 7.7 and a maximum perceived intensity of IV (Light) in Jakarta, the capital and largest city of Indonesia. There were no direct effects of the earthquake's shaking due to its low intensity, and the large loss of life from the event was due to the resulting tsunami, which inundated a 300 km (190 mi) portion of the Java coast that had been unaffected by the earlier 2004 Indian Ocean earthquake and tsunami that was off the coast of Sumatra. The July 2006 earthquake was also centered in the Indian Ocean, 180 kilometers (110 mi) from the coast of Java, and had a duration of more than three minutes.
Point Arena Light is a lighthouse in Mendocino County, California, United States, two miles (3 km) north of Point Arena, California. It is approximately 130 mi (210 km) north of San Francisco, in the Fort Point Group of lighthouses. The lighthouse features a small museum and gift shop. Guided tours of the light station as well as self-guided tours of the grounds are available daily.
The 2010 Chile earthquake and tsunami occurred off the coast of central Chile on Saturday, 27 February at 03:34 local time, having a magnitude of 8.8 on the moment magnitude scale, with intense shaking lasting for about three minutes. It was felt strongly in six Chilean regions that together make up about 80 percent of the country's population. According to the United States Geological Survey (USGS) the cities experiencing the strongest shaking—VIII (Severe) on the Mercalli intensity scale (MM)—were Concepción, Arauco, and Coronel. According to Chile's Seismological Service, Concepción experienced the strongest shaking at MM IX (Violent). The earthquake was felt in the capital Santiago at MM VII or MM VIII. Tremors were felt in many Argentine cities, including Buenos Aires, Córdoba, Mendoza, and La Rioja. Tremors were felt as far north as the city of Ica in southern Peru.
The 1992 Cape Mendocino earthquakes occurred along the Lost Coast of Northern California on April 25 and 26. The three largest events were the M7.2 thrust mainshock that struck near the unincorporated community of Petrolia midday on April 25 and two primary strike-slip aftershocks measuring 6.5 and 6.6 that followed early the next morning. The sequence encompassed both interplate and intraplate activity that was associated with the Mendocino Triple Junction, a complex system of three major faults that converge near Cape Mendocino. The total number of aftershocks that followed the events exceeded 2,000.
On 11 March 2011, at 14:46 JST, a 9.0–9.1 undersea megathrust earthquake occurred in the Pacific Ocean, 72 km (45 mi) east of the Oshika Peninsula of the Tōhoku region. It lasted approximately six minutes, causing a tsunami. It is sometimes known in Japan as the "Great East Japan Earthquake", among other names. The disaster is often referred to as simply 3.11.
Coastal flooding occurs when dry and low-lying land is submerged (flooded) by seawater. The range of a coastal flooding is a result of the elevation of floodwater that penetrates the inland which is controlled by the topography of the coastal land exposed to flooding. The seawater can flood the land via several different paths: direct flooding, overtopping of a barrier, or breaching of a barrier. Coastal flooding is largely a natural event. Due to the effects of climate change and an increase in the population living in coastal areas, the damage caused by coastal flood events has intensified and more people are being affected.
The 1898 Mare Island earthquake occurred in Northern California on with a moment magnitude of 5.8–6.4 and a maximum Mercalli intensity of VIII–IX (Severe–Violent). Its area of perceptibility included much of northern and central California and western Nevada. Damage amounted to $350,000 and was most pronounced on Mare Island, a peninsula in northern San Francisco Bay. While relatively strong effects there were attributed to vulnerable buildings, moderate effects elsewhere in the San Francisco Bay Area consisted of damaged or partially collapsed structures, and there were media reports of a small tsunami and mostly mild aftershocks that followed.
An earthquake occurred off the coast of the Alaska Peninsula on July 28, 2021, at 10:15 p.m. local time. The large megathrust earthquake had a moment magnitude of 8.2 according to the United States Geological Survey (USGS). A tsunami warning was issued by the National Oceanic and Atmospheric Administration (NOAA) but later cancelled. The mainshock was followed by a number of aftershocks, including three that were of magnitude 5.9, 6.1 and 6.9 respectively.
