Loma Prieta (from Spanish ''loma'' -hill, ''prieta'' -dark) is high and is the highest peak in the

Santa Cruz Mountains The Santa Cruz Mountains, part of the Pacific Coast Ranges, are a mountain range in central and Northern California, United States. They form a ridge down the San Francisco Peninsula, south of San Francisco. They separate the Pacific Ocean from ...

Northern California Northern California (colloquially known as NorCal) is a geographic and cultural region that generally comprises the northern portion of the U.S. state of California. Spanning the state's northernmost 48 counties, its main population centers incl ...

. Although the 1989 Loma Prieta earthquake was named for this mountain, the actual epicenter was five miles southwest of the peak, across the

San Andreas fault The San Andreas Fault is a continental transform fault that extends roughly through California. It forms the tectonics, tectonic boundary between the Pacific Plate and the North American Plate, and its motion is Fault (geology)#Strike-slip fau ...

, in the

The Forest of Nisene Marks State Park The Forest of Nisene Marks State Park is a state park of California, United States, protecting a secondary forest in the watershed of Aptos Creek and Soquel Creek within the Santa Cruz Mountains. It is located outside Aptos, California and conta ...

. In the 19th century, the peak was called Mount Bache, a name given in honor of Alexander Dallas Bache; the name is no longer in use. From 1955 to 2005, the mountain was the longtime site for the transmitter tower of San Jose television station KNTV. In September 2005, it moved its transmitter northwest to San Bruno Mountain after it became the Bay Area's

NBC The National Broadcasting Company (NBC) is an American English-language commercial broadcast television and radio network. The flagship property of the NBC Entertainment division of NBCUniversal, a division of Comcast, its headquarters are l ...

affiliate.

Geology

Loma Prieta is the tallest peak in the

and it is common to see snow on the mountain during the winter. Loma Prieta and other nearby mountain peaks are pushed upward by local collision forces associated with a left bend in the

. Starting near

Uvas Canyon Uvas Canyon County Park is a natural park located in upper Uvas Canyon on the eastern side of the Santa Cruz Mountains, west of Morgan Hill, California. The park has several small waterfalls, some of which flow perennially, that feed into tri ...

, the fault stops trending northwest but instead bends west-northwest for about eight miles before continuing its northwest direction. This left bend is renowned among geologists as a archetypal restraining bend which acts to oppose

strike-slip In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

motion along the fault. From the perspective of Loma Prieta and other mountains atop the

Sierra Azul block Sierra (Spanish for "mountain range" and "saw", from Latin '' serra'') may refer to the following: Places Mountains and mountain ranges * Sierra de Juárez, a mountain range in Baja California, Mexico * Sierra de las Nieves, a mountain range i ...

, the

Pacific Plate The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate. The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and Iza ...

is trying to shear them off the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacific ...

but can't break them off. Rather, the resulting

transpression In geology, transpression is a type of strike-slip deformation that deviates from simple shear because of a simultaneous component of shortening perpendicular to the fault plane. This movement ends up resulting in oblique shear. It is generally v ...

force pushes up the local terrain and helps explain why these are the highest peaks in the

Astronomy

From 1976 through 1990 amateur astronomer

Donald Machholz Donald Edward Machholz (October 7, 1952 – August 9, 2022) was an American amateur astronomer who was credited with the discovery of 12 comets that bear his name. Personal life and death In 2014, he married photojournalist Michele Machhol ...

set up his telescope an average of 120 times a year on the south slope of this mountain to search for comets. From this site he discovered three new comets that bear his name, including Periodic Comet Machholz 1

96P/Machholz Comet 96P/Machholz or 96P/Machholz 1 is a short-period sungrazing comet discovered on May 12, 1986, by amateur astronomer Donald Machholz on Loma Prieta peak, in central California using binoculars. On June 6, 1986, 96P/Machholz passed from t ...

on May 12, 1986. The first official West Coast

Messier marathon A Messier marathon is an attempt, usually organized by amateur astronomers, to find as many Messier objects as possible during one night. The Messier catalogue was compiled by French astronomer Charles Messier during the late 18th century and co ...

was conducted from this site in March 1979.

References

External links

* {{Authority control Mountains of Santa Clara County, California Mountains of the San Francisco Bay Area Santa Cruz Mountains Mountains of Northern California

Geology

Astronomy

See also

References

External links