ApBIfr, 1917. MONTHLY WEATHER REVIEW. 187
f m y Auckland, New Zealand, aa a violent eruption of the volcano W began Sunday snd etifiontinua. Two persona have been
8t. Lot&, Mo., Apt. 9, 1917.
A; distinct earth uake ehock waa felt for s e v d eeconde thie after- noon thmughout t L eectaon. A number of windowe were broken and eeveral chimnep were knocked down. The after-vibrati6ns continued for eight minutes. (h o c . Press.) [See Table 1 and note hereunder, this h u e of the REVIEW.]
Santa Barbma, Cal., Apt. 12, 1917.
A severe earthquake shock was felt here at 8 o'clock to-night. No damage waa done. Ventura and Oxnard, 20 and 30 miles eaat, reepect- ively along the coaat, also felt the ehock but experienced no damage.
(Assdc. Rea.)
Loa Angeles, Cal., d r. 20, 1917.
Two earthquake docks in rapid aucceesion were felt in vanom parte of eouthern California late to-night. No damage wae reported. (h c . Efm.)
London Apr. $7, 1917,S:S a. m. A vio\ent earthquake in Tuscany and Umbria ia reported in a Rome diapaFch to the Exchange Telegraph Co. to have occurred on Thursday
mormq Many ereone are reported killed at Monterchi, near Arezzo, the capital of g e Province of that name. Considerable material h g e is ale0 reported. (k c . Rem.)
R m , Apt. 80,1917.
Earthquake ehocka were reported at Monterchi teday, the aame district laid waste by earth tremora laat week. (United Preas.)
k i r n h o c . Press.)
S S d . 34/ c r 7 u ) TEE 'MISSOWI EABTHQUAKE OF APRIL 9,1917.
By RUY H. FINCH, Aasietant.
[8&molglarl InvwtIgatlons, Weather Bureau, May 29,1917.1
before 3 . m., central
in 10 different States.
It was felt over most of Missouri and Illinois, and at many places in Iowa, Wisconsin, Indiana, Kentucky, Tennessee, Mississip i , Arkansas, and Kansas. At first it
Madrid region, but later re orts indicate that the epicenter
Most of the information relative to this quake waa obtained from some 160 question cards filled out by co-
operative observers of the Weather Bureau-postmasters and others-most of whom rendered these re orts
were still fresh in their minds. The majority of the accounts thus received are given in some detail in Table
1, gage 182, of this issue of the REVIEW; their intensities an geographical distribution are shown on the accom- panylng isoseismal map, figure 1.
As was recently pointed out by Montessus de Ballore,'
the use of isoseismals drawn from estimates of intensities that a t best are bound to be at variance is unsatisfacto .
relative distribution of intensities than would be had if omitted. The area over which this quake was felt, elli tical in
In addition to
near the mid dp e of the east-
was thought that t E. e quake had its origin in the New
was somewhere between t R ere and St. Louis.
shortly dter the occurrence of the shock while its e E ects
Nevertheless such isoseismals give a better idea of t Y e
sha e, extends about 600 miles in a north-south x 'rection ancfover 500 d e s easbwest,
200,000 square miles. instrumentally recorded a t St. Louis, Mo. and the University Kans., sli kt records were also obtained at St. Ignatius Colle e, develand, Ohio, about 520 miles away, and the
I WeaLer Bureau, Washington, D. C., about 760 miles from
,@e epicentral region. The beginning of the disturbance as given by the m& jority of observers was 2h 52" to 2h 53" p. m. (Central
time). The time at ori 'n as calculated from the seismo- graph record of the &versity of Kansas was 2h 52m
24O f 50. This is in fair agreement with the record ob- tained at St. Louis University, within a very short dis- tance of the origin, which be an at Zh 52" 30' p. m.
tory bounded b the V isoseismal. Within the VI iso-
preceded and accompanied the shock. No good evidence as to the direction of the vibrations is at hand, though the majority of the observers thou ht it was east-west. The observer at Ironton, Mo., Mr. % . H. Delano, says that he looked down and could see the earth rock-rise up and sway back and forth as from west to east. The damage occasioned by this quake was slight. Some windows were broken, bncks shaken from chime s,
and laster cracked over most of the territo boundedgy
pavement in different arts of St. Louis. A ainter workin on a ladder in 2 ranite City, Mo., was sha ri en off and f into a flower arden but was unharmed. Many people hurriedly left t eir homes in fright. The school children at Warrenton, Mo., and several other places, were thrown into a anic and were dismissed. As is well
Sounds were quite general f y reported within the terri-
seismal many p f aces reported that heavy rumbling both
the t I isoseismal. Several horses were t T rown to the
5
elf
known, birds an cp many other animals are more sensitive to
over most of the by the V
in the southern half of the VI isoseismal area.
The middle Mississippi Valley the southern Appala- chian region, the Atlantic Coastai Plain in the vicinity of Charleston, S. C., northern and eastern New York, and New En land are the well-known seismic regions of the
of the middle Mississippi Valley quakes occur in the New Madrid region. Two quakes, one occurring on May 26,
1909, the other on January 2, 1912, and described by Udden apparently had then origin southwest of Chica.go. Scarcely a year asses without one or more quakes being
whose ori '11 appears to have been either 8 little to the south of &. Louis or near New Madrid, was not quite as severe as the one under discussion. Another that occurred on October 31, 1895, was probably the most severe since the great shocks of 1811-12. The last shock of note in this region occurred on December 7,1915, when an intensity of V Rossi-Ford was re orted. Several ob- servers ventured the assertion that %e qua.ke under dis- cussion was the most severe since the great New Madrid earth uake, and this may be true for the region about St. Louisxut is improbable as regards southeastern Missouri. Jud 'ng from the distance to which the waves of this distur ance was propa ated it seems robable that the origin was a t some dep below the su ace. It is known that a series of faults, runnin in a general east-west direc- tion, occur in the underlying B aleozoic rock of the central region of this earthquake, and i t is probable that the recent shake had its origin in one or more of these faults.
eastern 6 nited States. Most, though by no means all,
felt in the New E adrid region. One on October 7, 1857,
& 1R B
1 Bull., Bels. sac. Am&.
188 MONTHLY WEATHER REVIEW. Bparzl, 191.7
0
d
Fig. l.-bdmn& of the eerthqmke of April 9,1917, in Missouri and Illinois. Arabic numbers opposite plsoes indicate Rossi-FmlintPmalties.