[Geysers] Multiple Burst eruptions of Grand

[Lynn Stephens]

To put today’s 6-burst eruption of Grand in perspective:  The last reported eruptions exceeding 5 bursts occurred in 1996 when there were three such eruptions--two 5+1 (5 regular bursts plus one afterburst) and the August 2 eruption of 11 bursts.  In 1995 there was a 10+1 burst eruption on July 10 and a 6 burst eruption on October 17.
 
While four burst eruptions were fairly common through 1997, four burst eruptions became rare starting in 1998.  Here is some data on reported eruptions with four or more bursts from 1992 through 2009:
                                                4 burst             5 burst                         average
1975                                        18.3%              3.7%                            2.87
2005                                        0.7%                0.0%                            1.51  
 
1992                                        21                    
1993                                        34                    
1994                                        26                    5B on 9/17 and 10/10
1995                                        26                    5B  on 5/27, 9/10
5+1 on 8/21
6 on 10/17
10+1 on 7/10
1996                                        22                    3+1 on 6/16
                                                                        5+1 on 2/9 and 6/25
                                                                        11 on 8/2
1997                                        39                    3+1 on 6/23 and 6/27
                                                                        5B on 5/17, 8/31, 9/6
1998                                        6
1999                                        1 on 10/8         3+1 on 7/16
2000                                        6 (5/12, 6/15, 7/11, 7/13, 9/7, and 10/5)
2001                                        2—7/13 and 8/15
2002                                        1 on 5/25         4+1 on 8/4
2003                                        2—6/6 and 10/6
2004                                        none
2005                                        2—6/21 and 8/19
2006                                        none
2007                                        none
2008                                        2—7/27 and 7/29
2009                                        none
2010                                                                3+1 on 4/30
 
Note that 1997 was the last year with a "decent" chance of seeing 4-burst eruption.
 
Lynn Stephens  		 	   		  
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