Have you ever wondered what would happen if a tsunami were to hit the west coast or if Mt Lassen were to erupt (Mt. Diablo is not a volcano) or perhaps a dam breaks, maybe an asteroid were to strike the earth. I’ve got some answers for you.
A tsunami is a set of ocean waves caused by any large, abrupt disturbance of the sea-surface. If the disturbance is close to the coastline, local tsunamis can demolish coastal communities within minutes. A very large disturbance can cause local devastation and export tsunami destruction thousands of miles away. The word tsunami is a Japanese word, represented by two characters: tsu, meaning, “harbor”, and nami meaning, “wave”. Tsunamis rank high on the scale of natural disasters. Since 1850 alone, tsunamis have been responsible for the loss of over 420,000 lives and billions of dollars of damage to coastal structures and habitats. Most of these casualties were caused by local tsunamis that occur about once per year somewhere in the world. For example, the December 26, 2004, tsunami killed about 130,000 people close to the earthquake and about 58,000 people on distant shores. Predicting when and where the next tsunami will strike is currently impossible. Once the tsunami is generated, forecasting tsunami arrival and impact is possible through modeling and measurement technologies
Tsunamis have been recorded in California over the period from 1851 to the present. The larger more destructive tsunamis approach from the ocean. Tsunamis caused by local major earthquakes have been small, typically 2 foot high or less, within San Francisco Bay.
The highest tsunami that has been recorded for the Bay occurred in March 1964 as a result of the 9.2 Richter magnitude Alaskan earthquake. This wave reached a height of 7.5 feet at the entrance to the San Francisco Bay. Comparisons of tsunami heights at the entrance to San Francisco Bay and at locations around the Bay led to the conclusion that the height reduced to half at Richmond and to about ten percent at the north and south ends of the Bay.
Earthquakes can cause tsunami and seiches (oscillating waves in enclosed water bodies) in the Bay. Portions of Pittsburg are located adjacent to Suisun Bay, where low-lying, tsunami or seiche inundation is a possibility. However, projected wave height and tsunami run-up is expected to be small as the waves move towards the interior portions of the Delta
In May 1915, Lassen Peak, California, the southernmost active volcano in the Cascade Range, erupted explosively. Avalanches, mudflows, and flows of hot ash and gas devastated nearby areas, and volcanic ash fell as far away as 200 miles to the east. The Lassen area remains volcanically active, and the volcano hazards demonstrated in 1915 still can threaten not only nearby areas but also more distant communities.
Although extremely unlikely today, very large eruptions have occurred in the Lassen region in the distant past. For example, about 600,000 years ago there was an eruption 50 times larger than the 1980 eruption of Mount St. Helens. Because some winds at the time of that eruption were blowing southward, ash several inches thick was deposited as far south as the San Francisco Bay area. A similar eruption today could affect communities anywhere in northern California and northwestern Nevada, depending on wind direction. Even a light dusting of volcanic ash can close roads and seriously disrupt communications and utilities during and for many weeks after an eruption.
Just 20 miles beneath the earth’s surface, in Yellowstone Park, lays a pressurized ocean of molten rock looking for a way out. A massive release of that molten rock would create a supervolcano, arguably the largest natural disaster humanity would ever face. Unlike regular volcanoes, which are shaped like mammoth cones, supervolcanoes spring from massive canyons — calderas — that measure hundreds of miles across. Underneath their surface is a vast lake of lava. When the underground liquid rock — magma — bursts forth to the surface, a series of violent, massive explosions could occur in a wide-ranging eruption that could last several days. It would incinerate anyone within a hundred miles, and layers of ash would blanket much of the earth. The ash cloud would become so thick it could cover the sun, causing global temperatures to plummet.
Scientists estimate that the Yellowstone area will experience a supervolcano eruption approximately once every 600,000 years. The last one occurred more than 630,000 years ago.
There are 28 water retention facilities (dams and reservoirs) in Contra Costa County that have the capability of flooding significant population centers if they were to fail. None of these dams or reservoirs are located in the Oakley area.
A breach in Shasta Dam, although very unlikely, would devastate the entire northern Central Valley. The Sacramento River and its tributaries would overtop levees and banks. Massive flooding in the low lands and along the river route would occur to about Knights Landing where it would lose momentum. An Oroville Dam failure would impact populations southwest along the Feather River basin to about the Yolo Bypass. Sacramento County may experience flood consequences greater than those anticipated should any of these dams catastrophically fail. A failure at Camanche Dam would affect the Delta and possibly slow the flow of other rivers through the Delta.
The Earth orbits the Sun in a sort of cosmic shooting gallery, subject to impacts from comets and asteroids. It is only fairly recently that we have come to appreciate that these impacts by asteroids and comets (often called Near Earth Objects, or NEOs) pose a significant hazard to life and property. Most of the hazard is from asteroid impacts; comets make only a minor contribution. Although the annual probability of the Earth being struck by a large asteroid or comet is extremely small, the consequences of such a collision are so catastrophic that it is prudent to assess the nature of the threat and prepare to deal with it.
Studies have shown that the risk from cosmic impact increases with the size of the projectile. The greatest risk is associated with objects large enough to perturb the Earth’s climate on a global scale by injecting large quantities of dust into the stratosphere. Such an event could depress temperatures around the globe, leading to massive loss of food crops and possible breakdown of society. Such global catastrophes are qualitatively different from other more common hazards that we face (excepting nuclear war), because of their potential effect on the entire planet and its population. Various studies have suggested that the minimum mass impacting body to produce such global consequences is several tens of billions of tons, resulting in a ground burst explosion with energy in the vicinity of a million megatons of TNT. The corresponding threshold diameter for an asteroid is between 1 and 2 km. Smaller objects (down to tens of meters diameter) can cause severe local damage but pose no global threat
Today NASA is addressing this impact hazard by carrying out a comprehensive telescopic search for potentially hazardous near-Earth asteroids (NEAs). This program is called the Spaceguard Survey, and it has already resulted in the discovery of more than half the NEAs larger than 1 km diameter. The objective is to find 90% of the NEAs this large by the end of 2008.
Scientists have located more than 100,000 asteroids. Some are tiny, others as large as the state of Texas, and sooner or later, a huge one will crash with Earth. Astronomers already have their eyes fixed on an asteroid called Apophis, which is scheduled for a close encounter with Earth in 2029.
Scientists have calculated that, on April 13, 2029, Apophis will pass so close to Earth it will actually fly underneath our communication satellites. Depending on the path of the asteroid, scientists say there is a small chance Apophis could collide with Earth on its return orbit in 2036.