Northern California Coast Research Articles

Relative excitation of surface waves by earthquakes and underground explosions in the California-Nevada region

The results of a study of the relative excitation of long-period and short-period seismic waves by earthquakes and explosions in the California-Nevada region are presented. The Richter magnitude M, which is based on the amplitudes of short-period waves recorded at sites less than 600 km from the epicenter is used as a measure of short-period waves. A new parameter AR—the sum of the areas of the envelopes of the surface waves on certain three-component long-period instruments—is defined and used as a measure of the long-period waves. The surface wave parameter was determined from long-period seismograph records from Pasadena and Berkeley, California, Ruth and Reno, Nevada, and Palisades, New York. The four West Coast stations provide good azimuthal sampling of most of the events studied. Surface waves recorded at Palisades from the Fallon-Stillwater and Fairview Peak-Dixie Valley aftershock sequences were also studied. There is a wide range in the excitation of surface waves for a given Richter magnitude, both for explosions and, especially, for earthquakes. For any given earthquake there may also be a wide range in the excitation of surface waves as a function of azimuth, an indication of an asymmetrical radiation pattern. Generally speaking, the relative excitation of surface waves by explosions is much smaller than by earthquakes of the same Richter magnitude. Most of the earthquakes studied generated surface waves 5 to 10 times greater than the maximum observed for explosions of the same Richter magnitude. A comparison of the relative excitation of surface waves in different regions indicates a very large regional variation. Shocks off the coast of northern California generate relatively large surface waves, whereas shocks near Laguna Salada in Baja California often generate very small surface waves. An empirical curve is derived for the variation of the surface wave parameter AR as a function of distance. A formula for estimating the surface wave magnitude MS is derived from the parameter AR.

On a Surviving Representative of the Lepidotrichidae (Thysanura)1

TRICHOLEPIDION gertschi was found under decaying hark and in rotten logs of Douglas-fir in the mesophytic forest of the northern California Coast Range. It is closely related to the Baltic amber Lepidothrix pilifera Menge, differing mainly by the presence of ocelli. T. gertschi (and, by implication, also L. pilifera ), compared to the remaining Thysanura (families Nicoletiidae and Lepismatidae), is characterized by a large number of primitive characters, such as lack of scales, combined with presence of hypodermal pigment; the hypognathous head with exceptionally well developed occipital and postoccipital sclerites; the presence of three pectinate appendages to the laciniae; weakly developed thoracic sternal plates; a large number of abdominal stylets and exsertile vesicles; urosternites composed of a large, transverse sternite and posteriorly situated coxopodites, both elements being well developed even on the eighth and ninth segments of the male; the lack of a proventriculus; and the presence of seven ovarioles in each ovary. Specialized characters probably shared by both genera of Lepidotrichidae are the five-segmented tarsi; the modified ovipositor adapted to insertion of eggs into vegetable tissue; a group of specialized setae on the dorsal surface of the base of the penis; a very large number of testicular follicles; and forwardly directed diverticula of the vasa deferentia functioning as sperm reservoirs. Pairing of mature sperms in Tricholepidion is considered as a condition precursory to the development of spermatophores as observed in the Nicoletiidae; the presence of sensory cones on the underside of the median caudal filament in the males is equally indicative of relationship with the Nicoletiidae. The Lepidotrichidae are considered to be the most archaic known dicondylous insects ; their relic character is further stressed by their actual geographic distribution.

Thunderstorm Frequency in Northern California 1

Thunderstorms occur 2 to 5 times a year, chiefly in winter, on the coast of northern California, and 10 to 15 times a year, chiefly in summer, in the Great Basin. In the intervening Central Valley, 5 to 10 thunderstorms occur per year, mostly in late spring; a secondary maximum in early autumn is particularly important in starting forest fires. Correlations between numbers of days with thunderstorms at adjacent Weather Bureau stations are quite low; the highest found is 0.70 for summer thunderstorm days at Sacramento and Blue Canyon, 60 mi apart.

Earthquakes off the north Pacific Coast of the United States*

Abstract Epicenters of most of the larger earthquakes occurring off the coast of northern California and Oregon lie in two zones. One zone includes the north-facing submarine Gorda Escarpment, which extends nearly due west from Punta Gorda, and the south-facing Mendocino Escarpment as far offshore as long. 127° W. The other zone extends northwestward from the region of Cape Mendocino, indicating a linear extension of the San Andreas Rift zone as far as lat. 44° or 45° N.

Characteristics and Vegetation Relationships of Some Podzolic Soils Near the Coast of Northern California

AbstractA survey of vegetation and soil of wild lands in Mendocino County in northern California was completed in 1951. This survey disclosed the occurrence near the coast of some distinct podzolic soil, unique in relation to most other soils of the state, of unexpected extent, and having in part distinct vegetation associations.This northern coastal area has cool, nearly rainless but foggy summers and mild, wet winters. Precipitation averages between 35 and 40 inches; maximum temperatures during summer average about 65° F., and minimum temperatures during winter average about 40° F.; growing season is about 285 days.This paper deals with morphological and some chemical and physical characteristics of three soil series, the Blacklock, Noyo, and Caspar; their geographical distribution along the coast on sandy deposits, and their vegetation associations. The Blacklock, a Ground‐Water Podzol, occurs on flat or gently sloping surfaces and supports a unique “pygmy” forest, chiefly of Bolander pine and Mendocino cypress. The Noyo and Caspar are of questionable great‐soil‐group classification but both are distinctly podzolic in character, the Noyo showing a stronger degree of podzolization than the Caspar. The Noyo supports a cover chiefly of Bishop pine and the Caspar chiefly one of redwood and Douglas‐fir.

Waterfowl Losses in the Surf along the Northern California Coast

For many years residents of Humboldt County in northern coastal California have witnessed waterfowl perishing in the surf in large numbers. In the vicinity of Humboldt Bay and the Eel River the phenomenon is observed commonly and residents refer to these waterfowl victims as From November 1 to December 31, 1952, a preliminary study of this unusual condition was made and pertinent facts are reported here. The area where occur extends for a distance of approximately 25 miles from Centerville Beach north to Clam Beach, California. This includes the mouths of the Eel and Mad Rivers, North and South Spit of Humboldt Bay, and the Clam Beaches north of Arcata, California. The shore line in most of this area consists of steeply sloping beaches which cause short but forceful wave action during heavy seas. During a severe storm this wave action digs into the shore and for a distance of 200 to 400 feet from the beach the surf is saturated with sand. Immediately behind the beach is a series of small, sparsely vegetated sand dunes, and extending back from the sand dunes for several miles the land is largely agricultural. Several thousand acres are planted to permanent pasture with interspersed barley fields. On the pasture area of low rolling terrain, low spots fill with water in winter, thus making ideal resting and feeding areas for waterfowl. Many natural streams and sloughs pass through the farming area. The pasture areas are utilized primarily for grazing of dairy cattle and sheep. During hunting season waterfowl feed on ponds in the pastures from late afternoon until shooting begins in the morning, when they leave the farming area and fly to the ocean. They settle down one-half to one mile from shore in rafts of 200 to 3,000 birds. During the day smaller flocks may be seen continually flying from ocean to fields. Excessive losses of birds usually occur in moderately rough seas immediately following severe storms and with heavy fog off shore. At these times winds are usually from the southwest or in an easterly direction. Sanded birds occur on the beaches immediately following low tide. Observed losses were heaviest among surface-feeding ducks, and in order of decreasing prevalence the following species of waterfowl appeared to be most affected by sanding: baldpate (Mareca americana), pintail (Anas acuta tzitzihoa), mallard (Anas p. platyrhynchos), green-winged teal (Anas carolinense), lesser scaup (Aythya affinis), canvasback (Aythya valisineria) and redhead (Aythya americana). Other sanded birds included the western grebe (Aechmophorus occidentalis) and Baird's cormorant (Phalacrocorax pelagicus resplendens). At numerous times during past years a limited number of black brant (Branta nigricans) also have been affected by sanding but none were observed during the period of this study. Th heaviest concentrations of ducks and, in turn, the greatest losses occur near the m uth of the Eel River. During heavy seas this area is particularly rough, with occasional w v s breaking as far as a mile from shore. The birds sleep in concentrated groups and drift shoreward with the wind. Occasionally a high wave breaks far from shore and engulfs a group of resting ducks. They are then rolled into the area of heavy sand, and once their feathers become saturated with sand and water the seem helpless to maintain themselves in rough water. Birds attempting to re-enter open water are picked up by the surf and rolled back into the sand. Loss of waterfowl in this manner usually occurs several times during the year but is prevalent mainly during the hunting season. At these times the birds seek sanctuary in the ocean as an escape from hunters who harass them regularly on inland feeding

The History of the Lumber Industry in Humboldt County

THE GREAT redwood forest which once covered a large part of the Northern Hemisphere is now concentrated principally in a narrow 50o-mile strip along the coast of northern California. In the heart of this region lies Humboldt County. Soon after the first white men settled in the area in 1850 they began to take advantage of this great natural resource. Because of the tremendous size and weight of the redwood logs, they could not be handled and sawed with the primitive facilities of the pioneer lumbermen. As a result, the manufacture of lumber was at first confined to the pine, spruce, and fir-woods with which the early timbermen were familiar-and the redwoods were not cut until the mechanical means for

BREAKWATER CONSTRUCTION

Upon receipt of an invitation to participate in this conference and present a paper on the subject of Breakwater Construction, I was happy to accept, feeling that I would benefit to a far greater degree than my contribution to a subject in which I, and the concern which I represent, have had a deep interest for many years. Our experience embraces some of the major jetty and sea wall construction in San Francisco Bay, viz: Treasure Island, Mare Island, Alameda Naval Air Station, Sacramento and San Joaquin River bank protection and other jetties along the Northern California Coast, including Crescent City. This paper is limited to breakwater construction on the basis of our experience previously mentioned. The subject has been divided into two parts, namely, (1) construction of jetties, or breakwaters which can be built by use of floating equipment and (2) construction of jetties which are not practicable to be built by use of floating equipment.

Earthquakes off the coast of northern California*

SummaryThe epicenters as located for the earthquakes of July 6, 1934, January 2, 1935, and June 3, 1936, indicate that earthquakes centering off the coast of Humboldt County do not originate on a linear extension of the San Andreas fault in Mendocino County. Figure 1 shows the epicenters of these shocks as located by two methods, and also the epicenter of the earthquake of January 31, 1922, as located by Professor Macelwane.On the basis of least square residuals alone, the epicenters located by assuming a straight-line travel-time curve for Pn to Δ=18° are better than those located by the Jeffreys-Bullen curves. But for the shock of June 3, 1935, the epicenter located by the first method is inconsistent with the S-P interval at Ferndale, whereas that obtained by the second method is consistent. For the other two shocks the epicenters located by the two methods are little different in position.Whereas the July 6 shock shows a definite Sn travel-time curve with an intercept approximately equal to that of the Pn curve, the other two earthquakes show a marked wave preceding Sn and almost masking it at the coastal stations south of the epicenter. The travel-time curve of this wave has an intercept about 15 seconds below that of Pn. This wave is longitudinal and has a period of 4.35 km/sec. It is suggested that it is P in the sedimentary layer, although objections to such an interpretation are cited.The travel-time curve of P for the July 6 shock between 26° and 40° indicates that it is composed of two nearly straight branches rather than the more smooth curve of Jeffreys and Bullen.

The uric acid content of the blood of the stellar sea-lion.

A year ago, in the course of a general investigation of the body fluids of the Stellar sea-lion, indigent to the coast of northern California, it was observed, quite accidentally, that the uric acid of the blood apparently undergoes a considerable increase on standing. A recent and more complete study of the same question has confirmed the earlier results completely. The uric acid content of the fresh blood of four animals was found to vary from a bare trace to two milligrams per hundred cubic centimeters, according to the method of determination used. After standing for eight days on ice the apparent uric acid content had increased to as high as seven milligrams per hundred cubic centimeters, and remained at approximately this level until the thirtieth day, when the experiments were discontinued. Even after eight hours of standing at room temperature the apparent uric acid content had increased considerably. The determinations were made by three different methods, the direct colorimetric method of Benedict; the zinc precipitation method of Morris and hlacleod; and the silver precipitation method of Folin and \Vu. The three methods did not give concordant results for the same samples of blood, the amounts of uric acid indicated in each case being in the descending order in which the methods are listed above. It is significant, however, that the difference in the results from the three different methods remained practically constant, irrespective of the absolute uric acid level. In other words, the substance which accumulates in the blood on standing is precipitated by both zinc and silver. Whether or not these discrepancies in the results from the three methods are inherent in the methods themselves is of no concern in this present investigation.

Mailliard on Field Work in Northern California in 1921 Field Work among the Birds and Mammals of the Northern Coast of California in 1921 Joseph Mailliard

Mailliard on Field Work in Northern California in 1921 Field Work among the Birds and Mammals of the Northern Coast of California in 1921 Joseph Mailliard

The Geomorphogeny of the Coast of Northern California. Andrew C. Lawson

Previous articleNext article FreePublicationsThe Geomorphogeny of the Coast of Northern California. Andrew C. Lawson A. R. W.A. R. W. Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Journal of Geology Volume 3, Number 1Jan. - Feb., 1895 Article DOIhttps://doi.org/10.1086/607138 Views: 23Total views on this site PDF download Crossref reports no articles citing this article.