Original sentence: Another missionary, Titus Coan, observed and wrote about erruptions in the 19th century.Crater activity began to increase when between March 10 and March 14, 2008 gas began to vent  from the east wall fumarole directly below the Crater Overlook; however the gas event was only a prelude when in the wee hours (02:58 am  HST) of March 19, 2008 HVO personnel thought they were experiencing seismic events, but sunrise revealed a 20–30 metre (65–100 foot) diameter hole blown in the side where the vent once was; scattering debris and spatter across  and damaging the Crater Overlook.Since the vent's first appearance, 5.5 months ago, there have been six siginificant explosive events (the latest being September 2, 2008); changing the vent to its present shape of 65 meters or 215 feet across
Edited sentence: Another missionary, Titus Coan, observed and wrote about eruptions in the 19th century.Crater activity began to increase when between March 10 and March 14, 2008 gas began to vent  from the east wall fumarole directly below the Crater Overlook; however the gas event was only a prelude when in the wee hours (02:58 am HST) of March 19, 2008 HVO personnel thought they were experiencing seismic events, but sunrise revealed a 20–30 metre (65–100 foot) diameter hole blown in the side where the vent once was; scattering debris and spatter across  and damaging the Crater Overlook.Since the vent's first appearance, 5.5 months ago, there have been six significant explosive events (the latest being September 2, 2008); changing the vent to its present shape of 65 meters or 215 feet across