Hi Barbara. A quake of M=6.8 more then likely won’t generate a tsunami. The “moment tensor solution” shows the quake occurred on a normal fault which means the first motion was down. That kind of quake can cause a tsunami if the quake is large enough.

You may be interested in knowing that there is a potential for a tsunami at Lake Tahoe.

“University of Nevada, Reno geologists have been modeling different quake scenarios for Lake Tahoe. According to their calculations, if a magnitude 7 quake struck either of two major faults under the lake, the bottom could open like a trapdoor, with a chunk of it suddenly dropping as much as 4 m. Just behind it would fall a huge, sinking slosh of water—generating a giant wave that would reach the surface, gather strength, and come barreling to shore as a tsunami.”

“And that's just the beginning. The scientists think the tsunami, in turn, would create so-called seiche waves, mountainous waves that lurch from shore to shore for hours on end. "Think of the lake like a pan full of water. When you knock one end way down, the water surges and then sloshes back and forth for some time," says Gene A. Ichinose, a geophysics graduate student at Nevada-Reno and lead author of the group's study, which appeared in the April 15 Geophysical Research Letters. As in a jostled pan of water, some waves would likely splash past their usual borders—right into the homes and hotels that dot the Lake Tahoe shoreline.”

The quake lists are 100 miles and 200 miles radius from the M=6.8 quake.

http://www.seismo.unr.edu/htdocs/WGB/LakeTahoeTsunami/

catalog=ANSS
start_time=1898/01/01,00:00:00
end_time=2005/12/05,18:07:09
minimum_magnitude=5.0
maximum_magnitude=10
event_type=E
delta=0 km to 160 km from (-6.21,29.60)
Date Time Lat Lon Depth Mag Magt Nst Gap Clo RMS SRC Event ID
----------------------------------------------------------------------------------------------
1975/03/26 03:40:48.20 -5.4500 30.2070 33.00 5.10 Mb 41 0.00 NEI 197503264003
1976/01/19 08:05:47.90 -5.4620 28.7360 33.00 5.20 Mb 6 0.00 NEI 197601194007
1977/07/06 08:48:38.20 -6.1810 29.5390 33.00 5.10 Mb 105 0.00 NEI 197707064003
1986/06/29 21:47:59.67 -5.3360 29.5390 20.20 5.20 Mb 117 1.13 NEI 198606294051
1986/07/10 05:02:20.43 -5.5150 29.0190 10.00 5.00 Mb 6 1.50 NEI 198607104011
1997/09/21 18:13:22.78 -7.3600 30.3700 10.00 5.90 Me 196 1.08 NEI 199709211050
1998/03/28 21:59:56.17 -6.0240 29.5250 10.00 5.30 Mb 199 1.01 NEI 199803282042
2003/04/10 16:03:56.08 -5.5550 29.5070 10.00 5.10 Mw 107 0.81 NEI 200304104055

catalog=ANSS
start_time=1898/01/01,00:00:00
end_time=2005/12/05,18:14:15
minimum_magnitude=5.0
maximum_magnitude=10
event_type=E
delta=0 km to 320 km from (-6.21,29.60)
Date Time Lat Lon Depth Mag Magt Nst Gap Clo RMS SRC Event ID
----------------------------------------------------------------------------------------------
1969/05/22 21:15:56.70 -3.5570 28.9480 33.00 5.00 Mb 7 0.00 NEI 196905224008
1975/03/26 03:40:48.20 -5.4500 30.2070 33.00 5.10 Mb 41 0.00 NEI 197503264003
1975/09/21 09:22:04.00 -7.9070 31.6110 33.00 5.50 Mb 6 0.00 NEI 197509214010
1976/01/19 08:05:47.90 -5.4620 28.7360 33.00 5.20 Mb 6 0.00 NEI 197601194007
1976/08/29 00:30:10.50 -7.3860 30.8660 33.00 5.20 Mb 5 0.00 NEI 197608294001
1977/07/06 08:48:38.20 -6.1810 29.5390 33.00 5.10 Mb 105 0.00 NEI 197707064003
1978/01/29 21:41:36.70 -3.9290 29.3500 10.00 5.30 Mb 10 0.00 NEI 197801294020
1979/10/25 17:58:31.50 -3.4120 29.0700 33.00 5.20 Mb 14 0.00 NEI 197910254017
1982/07/03 23:21:12.07 -3.7370 28.9510 10.00 5.20 Mb 103 0.96 NEI 198207034017
1982/07/04 02:22:14.08 -3.7780 28.9170 10.00 5.00 Mb 85 1.01 NEI 198207044004
1983/07/07 20:35:38.15 -7.2710 27.8440 10.00 5.80 Mb 210 0.92 NEI 198307074025
1983/07/07 21:43:18.32 -7.4880 28.0140 10.00 5.00 Mb 53 0.75 NEI 198307074026
1983/07/12 22:34:40.00 -7.5680 27.9410 10.00 5.10 Mb 60 0.95 NEI 198307124028
1983/07/12 23:11:14.11 -7.5550 28.0000 10.00 5.10 Mb 76 1.00 NEI 198307124030
1984/01/11 18:40:29.62 -6.2390 27.8610 10.00 5.50 Mb 161 1.04 NEI 198401114026
1984/07/31 22:19:12.83 -7.6290 28.0210 10.00 5.00 Mb 56 0.58 NEI 198407314022
1985/02/23 14:45:35.94 -6.9660 30.9280 10.00 5.70 Mb 155 0.78 NEI 198502234028
1985/11/28 17:40:44.85 -8.6690 30.0020 10.00 5.10 Mb 60 0.93 NEI 198511284037
1986/06/29 21:47:59.67 -5.3360 29.5390 20.20 5.20 Mb 117 1.13 NEI 198606294051
1986/07/10 05:02:20.43 -5.5150 29.0190 10.00 5.00 Mb 6 1.50 NEI 198607104011
1989/02/09 23:49:16.16 -8.5480 29.8360 35.40 5.20 Mb 127 0.86 NEI 198902094029
1990/09/18 04:55:42.03 -4.0610 29.4830 10.00 5.00 Mb 60 0.99 NEI 199009184006
1992/09/23 14:52:27.64 -6.1630 26.7180 11.20 5.60 Mb 258 1.09 NEI 199209234048
1993/07/31 02:32:45.84 -4.3970 28.3610 10.00 5.00 Mb 76 0.72 NEI 199307314005
1994/08/18 00:45:47.20 -7.4330 31.7510 25.20 6.00 Mb 408 1.00 NEI 199408184001
1995/12/11 17:54:39.45 -6.2240 26.7140 10.00 5.70 Mw 291 0.86 NEI 199512114058
1997/09/21 18:13:22.78 -7.3600 30.3700 10.00 5.90 Me 196 1.08 NEI 199709211050
1998/03/28 21:59:56.17 -6.0240 29.5250 10.00 5.30 Mb 199 1.01 NEI 199803282042
1999/05/07 02:10:41.99 -7.5060 31.6050 10.00 5.20 Mb 185 0.67 NEI 199905074009
1999/05/07 14:07:28.74 -7.4910 31.6830 10.00 5.60 Mb 241 0.68 NEI 199905074039
2000/10/02 02:25:31.31 -7.9770 30.7090 34.00 6.50 Me 415 1.13 NEI 200010024002
2000/12/02 04:16:41.75 -7.1500 27.7500 10.00 5.00 Mb 98 0.86 NEI 200012024015
2002/02/20 19:07:17.10 -7.6790 31.8950 38.50 5.50 Mw 247 0.74 NEI 200202204056
2003/04/10 16:03:56.08 -5.5550 29.5070 10.00 5.10 Mw 107 0.81 NEI 200304104055

• Lake Tahoe Tsunami