The activity in the northern U.S. which was discussed in detail in
the last report continued this morning with a Ml 3.5 in southwestern
Montana. The parameters of this event were:

O: 04Oct2001 10:41:59 45.8N 112.2W ML=3.5 NEIS MONTANA

This is the largest earthquake within 50 km of this epicenter
since a Ml 3.4 occurred 49 km west of here on Oct. 31, 1998. Four
earthquakes of Ml>=3.5 have occurred within 100 km of this epicenter
in the past 3 years. This location is south of Butte and Helena,
Montana.

Petra, as always, with her good instincts had anticipated an
event in this region earlier in September.

Petra's prediction had been (#9065 in archives):

"Re: Helena MT Forecast
Posted by Petra Challus on August 23, 2001 at 21:44:34:
Hi Lowell,

This forecast is the same as Don's, ie window and magnitude, however using
a circular radius of within 20 miles of the City of Helena, MT.

Though some may not remember that Helena MT has had a serious earthquake
past, I'm attaching a link which provides first hand accounts of several
quakes which occurred in Helena. Truly worthy of reading.

Don's Forecast had been:

Magnitude: 2.9-4.1
From: 08/27/2001PDT - To: 09/01/2001
Location: Kalispell, Montana
Lat: 48.2N - Long: 114.5W - Range: 40Km

• NEIS earthquake listing